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Figure 1: Closeup of a diode, showing the square shaped semiconductor crystal
.
Figure 2: Various semiconductor diodes.
^ Semiconductor diodes are symbolized in schematic diagrams such as Figure below .

^ It neither represents the forward voltage drop nor any “bulk” resistance in the semiconductor material of the diode itself, but rather is a figure dependent upon both quantities and will vary substantially with the particular ohmmeter used to take the reading.

^ The schematic symbol of the diode is shown in Figure above (b) such that the anode (pointing end) corresponds to the P-type semiconductor at (a).

Bottom: A bridge rectifier
Figure 3: Structure of a vacuum tube diode
.In electronics, a diode is a two-terminal electronic component that conducts electric current in only one direction.^ You should remember: 1.Current will only flow in one direction through a diode.
  • Diodes 19 January 2010 18:22 UTC www.bcae1.com [Source type: FILTERED WITH BAYES]

^ A diode allows current to flow in only ONE direction.

^ A diode is a two-terminal electronic device consisting of a single p-n junction.
  • p-n Diode or Junction Diode 19 January 2010 18:22 UTC www.siliconfareast.com [Source type: FILTERED WITH BAYES]

.The term usually refers to a semiconductor diode, the most common type today, which is a crystal of semiconductor connected to two electrical terminals, a P-N junction.^ In a junction diode the rectifying junction is formed between a p-type region and an n-type region of a semiconductor.

^ A diode is a two-terminal electronic device consisting of a single p-n junction.
  • p-n Diode or Junction Diode 19 January 2010 18:22 UTC www.siliconfareast.com [Source type: FILTERED WITH BAYES]

^ A crystal diode is made of two different types of semiconductors right next to each other.
  • Diodes 19 January 2010 18:22 UTC www.pbs.org [Source type: FILTERED WITH BAYES]

.A vacuum tube diode, now little used, is a vacuum tube with two electrodes; a plate and a cathode.^ The tube diode uses two active elements (cathode and plate) and one passive element (the filament or heater).
  • RF DesignLine : Design Resource for Automotive Engineering 19 January 2010 18:22 UTC www.rfdesignline.com [Source type: Reference]
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  • The RF Edge : Design Resource for Automotive Engineering 19 January 2010 18:22 UTC www.rfid-world.com [Source type: Reference]
  • http://www.planetanalog.com/encyclopedia/defineterm.jhtml?term=diode&x=&y= 19 January 2010 18:22 UTC www.planetanalog.com [Source type: FILTERED WITH BAYES]
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^ Figure 2: Structure of a vacuum tube diode .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ K PIV - 2.5 0 A General replacement diode used in Fender and other non-tube rectifier circuits .

.The most common function of a diode is to allow an electric current in one direction (called the diode's forward direction) while blocking current in the opposite direction (the reverse direction).^ A diode allows current to flow in only ONE direction.

^ If the diode is reverse-biased , the current will not flow.

^ Diodes Diodes are electronic components that conduct electric current in only one direction, functioning as a one-way valve.

.Thus, the diode can be thought of as an electronic version of a check valve.^ Diodes The diode is to electrons exactly as a check valve or one-way valve is to water.
  • Diode Theory 19 January 2010 18:22 UTC www.realroad.com [Source type: Original source]

^ Thus, the diode can be thought of as an electronic version of a check valve .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ Diodes A diode functions as the electronic version of a one-way valve.
  • Surplus Diodes 19 January 2010 18:22 UTC www.hrent.com [Source type: General]

.This unidirectional behavior is called rectification, and is used to convert alternating current to direct current, and extract modulation from radio signals in radio receivers.^ The process of converting alternating current to direct current is called rectification.
  • Diode Power Supply 19 January 2010 18:22 UTC www.utc.edu [Source type: Academic]

^ The alternating voltage is said to be rectified, or converted to direct current (DC).
  • diode (electron tube) -- Britannica Online Encyclopedia 19 January 2010 18:22 UTC www.britannica.com [Source type: Reference]

^ Rectifier diodes are used in power supplies to convert alternating current (AC) to direct current (DC), a process called rectification.

.However, diodes can have more complicated behavior than this simple on-off action, due to their complex non-linear electrical characteristics, which can be tailored by varying the construction of their P-N junction.^ Real diodes do not display such a perfect on-off directionality but have a more complex non-linear electrical characteristic, which depends on the particular type of diode technology.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Diodes however are far more versatile devices than that.

^ HOW DIODE WORKS: Diode is nothing more than a simplest p-n junction.
  • Diode - Associated Content - associatedcontent.com 19 January 2010 18:22 UTC www.associatedcontent.com [Source type: General]

.These are exploited in special purpose diodes that perform many different functions.^ There are different types of diode but their basic functions are the same.

^ These are industrial laser diodes, energy efficient, stable and reliable, offering the highest quality and performance on the market.

^ We even tried Transient Voltage Suppressor (TVS) devices whose function is similar to a Zener diode, but are made specially to protect electronic devices from power surges.
  • LASORB - ESD absorber for laser diodes 19 January 2010 18:22 UTC lasorb.com [Source type: FILTERED WITH BAYES]

.Diodes are used to regulate voltage (Zener diodes), electronically tune radio and TV receivers (varactor diodes), generate radio frequency oscillations (tunnel diodes), and produce light (light emitting diodes).^ Diodes can be used to separate the signal from radio frequencies.

^ Using diodes for voltage regulation is a not a very good selection.

^ The next of the diodes in the schematic is a varactor or tuning diode.

.Diodes were the first semiconductor electronic devices.^ What type of electronic device is the Diode?
  • diode Facts, information, pictures | Encyclopedia.com articles about diode 19 January 2010 18:22 UTC www.encyclopedia.com [Source type: Academic]

^ A diode is the simplest possible semiconductor device.
  • HowStuffWorks "Doping Silicon: Diodes and Transistors" 19 January 2010 18:22 UTC electronics.howstuffworks.com [Source type: FILTERED WITH BAYES]

^ Diode Logic makes use of the fact that the electronic device known as a diode will conduct an electrical current in one direction, but not in the other.

.The discovery of crystals' rectifying abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker diodes were made of crystals of minerals such as galena.^ Braun patented the crystal rectifier in 1899.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Braun patented the crystal rectifier in 1899 [3].

^ Cat's whisker diodes were also called crystal diodes and found application in crystal radio receivers.

.Today most diodes are made of silicon, but other semiconductors such as germanium are sometimes used.^ Other uses for the Circuit Breaker Diode .
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

^ The most commonly used semiconductor material is Silicon .

^ Today the most common diodes are made from ultrapure semiconductor materials such as silicon or germanium.

Contents

History

.Although the crystal semiconductor diode was popular before the thermionic diode, thermionic and solid state diodes were developed in parallel.^ Thermionic or gaseous state diodes .

^ More recent solid state diodes: .
  • Diode - GHN 19 January 2010 18:22 UTC www.ieeeghn.org [Source type: Reference]

^ History Although the crystal diode was popularized before the thermionic diode, thermionic and solid state diodes were developed in parallel.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.The basic principle of operation of thermionic diodes was discovered by Frederick Guthrie in 1873.[1] Guthrie discovered that a positively-charged electroscope could be discharged by bringing a grounded piece of white-hot metal close to it (but not actually touching it).^ Principle of operation of a diode .
  • Semiconductor diode | Electronics Area 19 January 2010 18:22 UTC electronicsarea.com [Source type: FILTERED WITH BAYES]

^ The principle of operation of thermionic diodes was discovered by Frederick Guthrie in 1873.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ The principle of operation of thermionic diodes was discovered by Frederick Guthrie in 1873 [1].

.The same did not apply to a negatively charged electroscope, indicating that the current flow was only possible in one direction.^ You should remember: 1.Current will only flow in one direction through a diode.
  • Diodes 19 January 2010 18:22 UTC www.bcae1.com [Source type: FILTERED WITH BAYES]

^ A diode allows current to flow in only ONE direction.

^ The diode allows current flow in only one direction.
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.The principle was independently rediscovered by Thomas Edison on February 13, 1880. At the time Edison was carrying out research into why the filaments of his carbon-filament light bulbs nearly always burned out at the positive-connected end.^ Thermionic diode principles were rediscovered by Thomas Edison on February 13, 1880 and he was awarded a patent in 1883 (US patent|307031), but developed the idea no further.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Check out Home Depot or Lowes, they carry standard base low wattage ’sign bulbs’, these usually have more resilient filaments that last longer when the bulbs are used in a frequent on/off environment.
  • Arduino traffic light - Hack a Day 19 January 2010 18:22 UTC hackaday.com [Source type: General]

^ Unlike light bulbs, LEDs rarely burn out unless their current limit is passed.

.He had a special bulb made with a metal plate sealed into the glass envelope, and he was able to confirm that an invisible current could be drawn from the glowing filament through the vacuum to the metal plate, but only when the plate was connected to the positive supply.^ If D 2 is ON, the current must be positive, and that will occur only when V 2 > 0 .

^ The current heats the filament, causing thermionic emission of electrons into the vacuum envelope.

^ Thermionic diodes are vacuum tube devices (also known as thermionic valves), which are arrangements of electrodes surrounded by a vacuum within a glass envelope, similar in appearance to incandescent light bulbs.

.Edison devised a circuit where his modified light bulb more or less replaced the resistor in a DC voltmeter and on this basis was awarded a patent for it in 1883.[2] There was no apparent practical use for such device at the time, and the patent application was most likely simply a precaution in case someone else did find a use for the so-called “Edison Effect”.^ The first diode was a modified light bulb.
  • Diode - GHN 19 January 2010 18:22 UTC www.ieeeghn.org [Source type: Reference]

^ For each circuit use the DMM as a DC voltmeter and measure the DC value of V L .
  • Analog Diode Circuits 19 January 2010 18:22 UTC www.uic.edu [Source type: Academic]

^ Thermionic diodes are vacuum tube devices (also known as thermionic valves), which are arrangements of electrodes surrounded by a vacuum within a glass envelope, similar in appearance to incandescent light bulbs.

.About 20 years later, John Ambrose Fleming (scientific adviser to the Marconi Company and former Edison employee) realized that the Edison effect could be used as a precision radio detector.^ The first thermionic diode was patented in Britain by John Ambrose Fleming (scientific adviser to the Marconi Company and former Edison employee[4]) on November 16, 1904 (U.S. Patent 803684 in November 1905).

^ The first thermionic diode was patented in Britain by John Ambrose Fleming (scientific adviser to the Marconi Company and former Edison employee on November 16 1904 US patent|803684 in November 1905.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Diluted shares add to the basic shares the number of in-the-money stock options minus the number of shares that the Company could buy back assuming it uses the proceeds from the exercise of these stock options.
  • Diodes Inc. - Investor Relations - FAQ 19 January 2010 18:22 UTC investor.diodes.com [Source type: News]

.Fleming patented the first true thermionic diode in Britain [3] on November 16, 1904 (followed by U.S. Patent 803,684 in November 1905).^ The first thermionic diode was patented in Britain by John Ambrose Fleming (scientific adviser to the Marconi Company and former Edison employee[4]) on November 16, 1904 (U.S. Patent 803684 in November 1905).

^ The first thermionic diode was patented in Britain by John Ambrose Fleming (scientific adviser to the Marconi Company and former Edison employee on November 16 1904 US patent|803684 in November 1905.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Thermionic diode principles were rediscovered by Thomas Edison on February 13, 1880 and he was awarded a patent in 1883 (US patent|307031), but developed the idea no further.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.The principle of operation of crystal diodes was discovered in 1874 by the German scientist Karl Ferdinand Braun.^ Principle of operation of a diode .
  • Semiconductor diode | Electronics Area 19 January 2010 18:22 UTC electronicsarea.com [Source type: FILTERED WITH BAYES]

^ The principle of operation of thermionic diodes was discovered by Frederick Guthrie in 1873.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ The principle of operation of crystal diodes was discovered in 1874 by the German scientist, Karl Ferdinand Braun [2].

[4] .Braun patented the crystal rectifier in 1899.[5] Braun’s discovery was further developed by Jagdish Chandra Bose into a useful device for radio detection.^ Braun patented the crystal rectifier in 1899.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Braun’s discovery was further developed by Jagdish Chandra Bose into a useful device for radio detection.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Braun patented the crystal rectifier in 1899 [3].

.The first actual radio receiver using a crystal diode was built by Greenleaf Whittier Pickard.^ The first radio receiver using a crystal diode was built around 1900 by Greenleaf Whittier Pickard.

^ Diodes for crystal receivers Diodes .
  • Diodes for crystal receivers 19 January 2010 18:22 UTC www.crystal-radio.eu [Source type: Academic]

^ Which diode can I use best in my crystal receiver?
  • Diodes for crystal receivers 19 January 2010 18:22 UTC www.crystal-radio.eu [Source type: Academic]

Pickard received a patent for a silicon crystal detector on November 20, 1906.[6]
.Other experimenters tried a variety of minerals and other substances, although by far the most popular was the lead sulfide mineral Galena.^ The most common kind of diode in modern circuit design is the semiconductor diode, although other diode technologies exist.
  • Introduction : DIODES AND RECTIFIERS 19 January 2010 18:22 UTC www.allaboutcircuits.com [Source type: FILTERED WITH BAYES]

^ The most common kind of diode in modern circuit design is the semiconductor diode , although other diode technologies exist.

.Although other substances offered slightly better performance, galena had the advantage of being cheap and easy to obtain, and was used almost exclusively in home-built “crystal sets”, until the advent of inexpensive fixed-germanium diodes in the 1950s.^ For high performance receivers, we can better use a suitable schottky diode.
  • Diodes for crystal receivers 19 January 2010 18:22 UTC www.crystal-radio.eu [Source type: Academic]

^ Diodes are manufactured using semiconductor materials such as silicon, germanium or selenium and are used as voltage regulators, signal rectifiers, oscillators and signal modulators / demodulators.
  • Diodes, Inc. - Company Profile | Supplier Information 19 January 2010 18:22 UTC www.globalspec.com [Source type: FILTERED WITH BAYES]
  • Information about Current Limiting Diodes 19 January 2010 18:22 UTC productsearch.machinedesign.com [Source type: Reference]

^ These cheap and easy to use devices rely on the ability of diodes to allow the flow of electrons when the voltage across them is in one direction but prevent that flow when the bias is reversed.
  • Simple mod turns diode into photon counter « the physics arXiv blog 19 January 2010 18:22 UTC arxivblog.com [Source type: FILTERED WITH BAYES]

.At the time of their invention, such devices were known as rectifiers.^ At the time of their invention, such devices were known as rectifiers.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ At the time of their invention such devices were known as rectifiers.

^ LED devices are mounted on a circuit board, which can be programmed to include lighting controls such as dimming, light sensing and pre-set timing.
  • Learn About LEDs : ENERGY STAR 19 January 2010 18:22 UTC www.energystar.gov [Source type: General]

.In 1919, William Henry Eccles coined the term diode from the Greek roots dia, meaning “through”, and ode (from ὅδος), meaning “path”.^ In 1919 William Henry Eccles coined the term diode from Greek roots; di means 'two', and ode means 'path'.

^ The term 'reverse recovery' refers to a delay in turn-off (i.e., the transition to a high resistance) of a diode when the current through it is reversed from the forward direction to the reverse direction.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

^ In 1919, William Henry Eccles coined the term ‘’’diode’’’ from Greek roots; ‘’di’’ means “two”, and ‘’ode’’ (from ‘’odos’’) means “path”.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

Thermionic and gaseous state diodes

.
Figure 4: The symbol for an indirect heated vacuum tube diode.
^ Vacuum tube diode symbol .

^ Figure 2: Structure of a vacuum tube diode .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ A few schematic symbols for diodes are: Figure 1 - schematic symbols for diodes .

From top to bottom, the components are the anode, the cathode, and the heater filament.
.Thermionic diodes are thermionic-valve devices (also known as vacuum tubes, tubes, or valves), which are arrangements of electrodes surrounded by a vacuum within a glass envelope.^ The next diode is the simplest form of vacuum tube or valve.

^ Thermionic diodes are vacuum tube devices (also known as thermionic valves), which are arrangements of electrodes surrounded by a vacuum within a glass envelope, similar in appearance to incandescent light bulbs.

^ Vacuum tube diodes Thermionic diodes are thermionic valve devices (also known as vacuum tubes), which are arrangements of electrodes surrounded by a vacuum within a glass envelope.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.Early examples were fairly similar in appearance to incandescent light bulbs.^ Early examples were fairly similar in appearance to incandescent light bulbs.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Thermionic diodes are vacuum tube devices (also known as thermionic valves), which are arrangements of electrodes surrounded by a vacuum within a glass envelope, similar in appearance to incandescent light bulbs.

^ Thermionic diodes are vacuum tubes, which are nothing but electrodes surrounded by a vacuum within a glass envelope similar in appearance to incandescent light bulbs.

.In thermionic valve diodes, a current through the heater filament indirectly heats the cathode, another internal electrode treated with a mixture of barium and strontium oxides, which are oxides of alkaline earth metals; these substances are chosen because they have a small work function.^ This indirectly heats the cathode, another filament treated with a mixture of barium and strontium oxides, which are oxides of alkaline earth metals; these substances are chosen because they have a small work function.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ The diode is OFF and the current through it is zero .

^ Small amounts of current can still flow through the diode.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.(Some valves use direct heating, in which a tungsten filament acts as both heater and cathode.^ (Some valves use direct heating, in which a tungsten filament acts as both cathode and emitter.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ The primary source of electrons in an electron tube; in directly heated tubes the filament is the cathode, and in indirectly heated tubes a coated metal cathode surrounds a heater.

^ The tube diode uses two active elements (cathode and plate) and one passive element (the filament or heater).

) .The heat causes thermionic emission of electrons into the vacuum.^ The current heats the filament, causing thermionic emission of electrons into the vacuum envelope.

^ The heat causes thermionic emission of electrons into the vacuum.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.In forward operation, a surrounding metal electrode called the anode is positively charged so that it electrostatically attracts the emitted electrons.^ In forward operation, a surrounding metal electrode, called the anode, is positively charged, so that it electrostatically attracts the emitted electrons.

^ When a mobile electron recombines with a hole, both hole and electron vanish, leaving behind an immobile positively charged donor on the N-side and negatively charged acceptor on the P-side.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
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^ When a positive voltage is applied to the anode (or plate), electrons emitted from the heated cathode flow to the plate and return to the cathode through an external power supply .
  • diode (electron tube) -- Britannica Online Encyclopedia 19 January 2010 18:22 UTC www.britannica.com [Source type: Reference]

.However, electrons are not easily released from the unheated anode surface when the voltage polarity is reversed.^ However, electrons are not easily released from the unheated anode surface when the voltage polarity is reversed and hence any reverse flow is a very tiny current.

^ We know that a diode allows current to go in one direction when the polarity of the voltage corresponds to the direction of the forward bias of the diode, and doesn't allow (cuts off) the current in the opposite direction when the polarity of voltage corresponds to the direction of the reverse bias of the diode.
  • Diode Power Supply 19 January 2010 18:22 UTC www.utc.edu [Source type: Academic]

^ When a positive voltage is applied to the anode (or plate), electrons emitted from the heated cathode flow to the plate and return to the cathode through an external power supply .
  • diode (electron tube) -- Britannica Online Encyclopedia 19 January 2010 18:22 UTC www.britannica.com [Source type: Reference]

.Hence, any reverse flow is negligible.^ In a sense, the diode acts as a "one-way valve" for current allowing large currents to flow under forward bias and only negligible -I s values under reverse bias.
  • Elecrtonics 1 Lab Experiment 4 Diodes 19 January 2010 18:22 UTC engr.astate.edu [Source type: Academic]

^ However, electrons are not easily released from the unheated anode surface when the voltage polarity is reversed and hence any reverse flow is a very tiny current.

^ Current can only flow from anode to cathode and not in the reverse direction, hence the "arrow" appearance.

.For much of the 20th century, thermionic valve diodes were used in analog signal applications, and as rectifiers in many power supplies.^ For much of the 20th century vacuum tube diodes were used in analog signal applications, and as rectifiers in power supplies.

^ For much of the 20th century, thermionic valve diodes were used in analog signal applications, and as rectifiers in many power supplies.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ {Diode Rectifier Manufacturer, many types} .
  • Diode Manufacturers, Rectifier, Schottky 19 January 2010 18:22 UTC www.interfacebus.com [Source type: Reference]

.Today, valve diodes are only used in niche applications such as rectifiers in electric guitar and high-end audio amplifiers as well as specialized high-voltage equipment.^ What are some of the end uses for Diodes products?
  • Diodes Inc. - Investor Relations - FAQ 19 January 2010 18:22 UTC investor.diodes.com [Source type: News]

^ Modern applications of tube diodes are generally limited to rectifiers in high-end audio amplifiers and other specialized high-voltage circuits.
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^ Can I use the Equipment Diode on my computer?
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

Semiconductor diodes

.A modern semiconductor diode is made of a crystal of semiconductor like silicon that has impurities added to it to create a region on one side that contains negative charge carriers (electrons), called n-type semiconductor, and a region on the other side that contains positive charge carriers (holes), called p-type semiconductor.^ Recall that electrons are the majority carriers in n-type material and holes in p-type material.
  • Elecrtonics 1 Lab Experiment 4 Diodes 19 January 2010 18:22 UTC engr.astate.edu [Source type: Academic]

^ This type of diode is called a zener diode.
  • Questions about Diodes - Ask.com 19 January 2010 18:22 UTC www.ask.com [Source type: General]

^ The resulting semiconductor material has an excess of current-carrying electrons, each with a negative charge, and is therefore referred to as " N-type " material with the electrons called "Majority Carriers" and the resultant holes "Minority Carriers".

.The diode's terminals are attached to each of these regions.^ Tunnel diodes: These diodes have a negative resistance region of operation that is caused due to quantum tunneling.

^ In general these devices operate in the infrared region, but newer diode lasers operating at a variety of specific visible wavelengths are rapidly being developed.
  • Olympus FluoView Resource Center: Diode Lasers - Interactive Java Tutorial 19 January 2010 18:22 UTC www.olympusconfocal.com [Source type: Reference]

^ Gunn diodes these are similar to tunnel diodes in that they are made of materials such as GaAs or InP that exhibit a region of negative differential resistance.

.The boundary within the crystal between these two regions, called a PN junction, is where the action of the diode takes place.^ A diode is a two terminal device using a PN junction.
  • Diode Manufacturers, Rectifier, Schottky 19 January 2010 18:22 UTC www.interfacebus.com [Source type: Reference]

^ See laser diode and PN junction .
  • RF DesignLine : Design Resource for Automotive Engineering 19 January 2010 18:22 UTC www.rfdesignline.com [Source type: Reference]

^ One region of semiconductor within the diode is called the P region.

.The crystal conducts conventional current in a direction from the p-type side (called the anode) to the n-type side (called the cathode), but not in the opposite direction.^ Current flows from the anode side to the cathode side.

^ This is when the electric current in the diode wants to circulate on opposite direction of the arrow (the arrow of the diode), or from the cathode to the anode.
  • Semiconductor diode | Electronics Area 19 January 2010 18:22 UTC electronicsarea.com [Source type: FILTERED WITH BAYES]

^ In a p-n diode, conventional current can flow from the p-type side (the anode) to the n-type side (the cathode), but not in the opposite direction.

.Another type of semiconductor diode, the Schottky diode, is formed from the contact between a metal and a semiconductor rather than by a p-n junction.^ A Schottky diode has a metal semiconductor junction as the Schottky barrier rather than the traditional semiconductor to semiconductor junction seen in conventional diodes.

^ Another type of semiconductor diode, the Schottky diode, is formed from the contact between a metal and a semiconductor rather than by a p-n junction.

^ Schottky diodes Schottky diodes are constructed from a metal to semiconductor contact.

Current–voltage characteristic

.A semiconductor diode’s behavior in a circuit is given by its current–voltage characteristic, or I–V graph (see graph at right).^ Current–voltage characteristic .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The graph on the right shows the electrical characteristics of a typical diode.

^ The voltage-current graph of a zener diode looks like this: .

.The shape of the curve is determined by the transport of charge carriers through the so-called depletion layer or depletion region that exists at the p-n junction between differing semiconductors.^ The region around the p-n junction becomes depleted of charge carriers and thus behaves as an insulator .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The region around the p-n junction becomes depleted of charge carriers and thus behaves as an insulator.

^ A semiconductor diode's current-voltage, or I-V, characteristic curve is ascribed to the behavior of the so-called depletion layer or depletion zone which exists at the p-n junction between the differing semiconductors.

.When a p-n junction is first created, conduction band (mobile) electrons from the N-doped region diffuse into the P-doped region where there is a large population of holes (vacant places for electrons) with which the electrons “recombine”.^ There are a large number of holes.

^ When a p-n junction is first created, conduction band (mobile) electrons from the N-doped region diffuse into the P-doped region where there is a large population of holes (places for electrons in which no electron is present) with which the electrons "recombine".

^ When a p-n junction is first created, conduction band (mobile) electrons from the N-doped region diffuse into the P-doped region where there is a large population of holes (places for electrons in which no electron is present) with which the electrons “recombine”.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.When a mobile electron recombines with a hole, both hole and electron vanish, leaving behind an immobile positively charged donor (dopant) on the N-side and negatively charged acceptor (dopant) on the P-side.^ The positive charge applied to the P-type material repels the holes, while the negative charge applied to the N-type material repels the electrons.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ When a mobile electron recombines with a hole, both hole and electron vanish, leaving behind an immobile positively charged donor on the N-side and negatively charged acceptor on the P-side.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ For each electron-hole pair that recombines, a positively-charged dopant ion is left behind in the N-doped region, and a negatively charged dopant ion is left behind in the P-doped region.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • Discover Electronics Online 19 January 2010 18:22 UTC www.discover-electronics-online.com [Source type: Reference]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.The region around the p-n junction becomes depleted of charge carriers and thus behaves as an insulator.^ The region around the p-n junction becomes depleted of charge carriers and thus behaves as an insulator.

^ Thus, two charge carriers have vanished.

^ The amount of this charge depends on the applied bias Vak since the size of the depletion region (the region where dopant atoms are ionized) varies with voltage.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

.However, the width of the depletion region (called the depletion width) cannot grow without limit.^ However, the depletion width cannot grow without limit.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • Discover Electronics Online 19 January 2010 18:22 UTC www.discover-electronics-online.com [Source type: Reference]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ The devices however have a maximum limit to the current and power in the zener or avalanche region.

^ Both devices, however, do have a limit to the maximum current and power in the clamped reverse voltage region.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.For each electron-hole pair that recombines, a positively-charged dopant ion is left behind in the N-doped region, and a negatively charged dopant ion is left behind in the P-doped region.^ The positive charge applied to the P-type material repels the holes, while the negative charge applied to the N-type material repels the electrons.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ When a mobile electron recombines with a hole, both hole and electron vanish, leaving behind an immobile positively charged donor on the N-side and negatively charged acceptor on the P-side.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ Doping gives: positively charged donors.

.As recombination proceeds more ions are created, an increasing electric field develops through the depletion zone which acts to slow and then finally stop recombination.^ The strength of the depletion zone electric field increases as the reverse-bias voltage increases.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ As recombination proceeds and more ions are created, an increasing electric field develops through the depletion zone which acts to slow and then finally stop recombination.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • Discover Electronics Online 19 January 2010 18:22 UTC www.discover-electronics-online.com [Source type: Reference]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ If an external voltage is placed across the diode with the same polarity as the built-in potential, the depletion zone continues to act as an insulator, preventing any significant electric current flow.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.At this point, there is a “built-in” potential across the depletion zone.^ At this point, there is a “built-in” potential across the depletion zone.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ At this point, there is a 'built-in' potential across the depletion zone.

^ At this point, there is a "built-in" potential across the depletion zone.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

.If an external voltage is placed across the diode with the same polarity as the built-in potential, the depletion zone continues to act as an insulator, preventing any significant electric current flow (unless electron/hole pairs are actively being created in the junction by, for instance, light.^ If the diode is reverse-biased , the current will not flow.

^ At this point, there is a 'built-in' potential across the depletion zone.

^ When the diode is ON , it has no voltage across it so it acts like a short circuit!

see photodiode). .This is the reverse bias phenomenon.^ This is the reverse bias phenomenon.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ This is the ‘’reverse bias‘’ phenomenon.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

However, if the polarity of the external voltage opposes the built-in potential, recombination can once again proceed, resulting in substantial electric current through the p-n junction (i.e. substantial numbers of electrons and holes recombine at the junction).. For silicon diodes, the built-in potential is approximately 0.6 V. Thus, if an external current is passed through the diode, about 0.6 V will be developed across the diode such that the P-doped region is positive with respect to the N-doped region and the diode is said to be “turned on” as it has a forward bias.
Figure 5: I–V characteristics of a P-N junction diode (not to scale).
.A diode’s 'I–V characteristic' can be approximated by four regions of operation (see the figure at right).^ A diode’s I–V characteristic can be approximated by four regions of operation (see the figure at right).
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ A diode's I-V characteristic can be approximated by two regions of operation.

^ The forward voltage drop of a diode is almost constant whatever the current passing through the diode so they have a very steep characteristic (current-voltage graph), as shown in figure 1.
  • Diodes - Electronics in Meccano 19 January 2010 18:22 UTC www.eleinmec.com [Source type: FILTERED WITH BAYES]

At very large reverse bias, beyond the peak inverse voltage or PIV, a process called reverse breakdown occurs which causes a large increase in current (i.e. a large number of electrons and holes are created at, and move away from the pn junction) that usually damages the device permanently. The avalanche diode is deliberately designed for use in the avalanche region. .In the zener diode, the concept of PIV is not applicable.^ In the zener diode, the concept of PIV is not applicable.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ In the zener diode , the concept of PIV is not applicable.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ For special purpose diodes like the avalanche or zener diodes, the concept of PIV is not applicable since they have a deliberate breakdown beyond a known reverse current such that the reverse voltage is "clamped" to a known value (called zener voltage).

.A zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is “clamped” to a known value (called the zener voltage), and avalanche does not occur.^ The breakdown voltage is the point at which a reverse voltage is conducted.

^ Figure 3 - zener voltage regulation diodes .

^ A zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is “clamped” to a known value (called the ‘’zener voltage’’), and avalanche does not occur.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.Both devices, however, do have a limit to the maximum current and power in the clamped reverse voltage region.^ The devices however have a maximum limit to the current and power in the zener or avalanche region.

^ The Current Limit is the maximum current the Current Source will deliver.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Both devices, however, do have a limit to the maximum current and power in the clamped reverse voltage region.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

.Also, following the end of forward conduction in any diode, there is reverse current for a short time.^ Forward Current: A specification of the laser diode.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ The reverse recovery time is short.

^ For general use, where the size of the forward voltage drop is less important, silicon diodes are better because they are less easily damaged by heat when soldering, they have a lower resistance when conducting, and they have very low leakage currents when a reverse voltage is applied.

.The device does not attain its full blocking capability until the reverse current ceases.^ Just to reiterate, even when the applied diode voltage reverses, real diode reverse current does not drop to zero INSTANTANEOUSLY , but instead, decreases more gradually.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

^ But, finally, note that the reverse current does not instantaneously drop to zero when the diode voltage goes negative.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

^ After a forward current has been passing in an SRD and the current is interrupted or reversed, the reverse conduction will cease very abruptly (as in a step waveform).

.The second region, at reverse biases more positive than the PIV, has only a very small reverse saturation current.^ Where I s is the reverse biased saturation current.
  • Advanced Lab - Photoelectric Effect:Light Emitting Diodes 19 January 2010 18:22 UTC www.physics.gatech.edu [Source type: Academic]

^ If the diode is reverse-biased , the current will not flow.

^ If D 2 is ON, the current must be positive, and that will occur only when V 2 > 0 .

.In the reverse bias region for a normal P-N rectifier diode, the current through the device is very low (in the µA range).^ Referring to the I-V characteristics image, in the reverse bias region for a normal P-N rectifier diode, the current through the device is very low (in the A range) for all reverse voltages upto a point called the peak-inverse-voltage (PIV).

^ Rectifier Diodes can pass high currents.
  • Diodes - Electronics in Meccano 19 January 2010 18:22 UTC www.eleinmec.com [Source type: FILTERED WITH BAYES]

^ The power losses in the diode are in this region very low compared to the rectified power.
  • Diodes for crystal receivers 19 January 2010 18:22 UTC www.crystal-radio.eu [Source type: Academic]

.However, this is temperature dependent, and at suffiently high temperatures, a substantial amount of reverse current can be observed (mA or more).^ However, electrons are not easily released from the unheated anode surface when the voltage polarity is reversed and hence any reverse flow is a very tiny current.

^ Just to reiterate, even when the applied diode voltage reverses, real diode reverse current does not drop to zero INSTANTANEOUSLY , but instead, decreases more gradually.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

^ For thermal control, almost any diode temperature stabilizer will probably do, as long as it supplies at least 1 amp - if you plan to do substantial cooling, you'll need more current of course.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

.The third region is forward but small bias, where only a small forward current is conducted.^ The third region is forward but small bias, where only a small forward current is conducted.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ In a sense, the diode acts as a "one-way valve" for current allowing large currents to flow under forward bias and only negligible -I s values under reverse bias.
  • Elecrtonics 1 Lab Experiment 4 Diodes 19 January 2010 18:22 UTC engr.astate.edu [Source type: Academic]

^ A small control pulse of current is all that is required to turn them on and when that pulse is removed the thyristor continues to conduct ,assuming a minimum holding current is maintained e.g.

.As the potential difference is increased above an arbitrarily defined “cut-in voltage” or “on-voltage” or “diode forward voltage drop (Vd)”, the diode current becomes appreciable (the level of current considered “appreciable” and the value of cut-in voltage depends on the application), and the diode presents a very low resistance.^ At higher currents the forward voltage drop of the diode increases.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ Forward Voltage changes as Forward Current changes, similar to a diode curve.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Vf is the forward voltage drop of a semiconductor.

.The current–voltage curve is exponential.^ The current–voltage curve is exponential.
  • PS Audio - High-Performance Home Audio Equipment 19 January 2010 18:22 UTC www.psaudio.com [Source type: FILTERED WITH BAYES]

^ The current–voltage curve is exponential .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ In its basic form, it says that the DC component of current increases roughly exponentially with forward voltage: .
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

.In a normal silicon diode at rated currents, the arbitrary “cut-in” voltage is defined as 0.6 to 0.7 volts.^ Silicon diodes have a forward voltage of approximately 0.7 volts.

^ In a normal silicon diode at rated currents, the voltage drop across a conducting diode is approximately 0.6 to 0.7 volts.

^ In this equation, v D and i D are the diode voltage and current and V T is the thermal voltage.
  • http://faculty.evansville.edu/ar63/courses/Tutorials/Diode_Modeling_1.html 19 January 2010 18:22 UTC faculty.evansville.edu [Source type: Academic]

.The value is different for other diode types — Schottky diodes can be rated as low as 0.2 V and red or blue light-emitting diodes (LEDs) can have values of 1.4 V and 4.0 V respectively.^ Figure 8 - connecting light emitting diodes (LED's) to supply .

^ Company Profile: Distributor of light emitting diodes (LEDs) & lamps.
  • Diodes on ThomasNet.com 19 January 2010 18:22 UTC www.thomasnet.com [Source type: General]

^ A light-emitting diode (LED) is categorized by its power consumption.
  • Light-Emitting Diode (LED) Display and Device Providers | Business.com 19 January 2010 18:22 UTC www.business.com [Source type: General]

.At higher currents the forward voltage drop of the diode increases.^ Measuring the diode forward voltage - how?

^ At higher currents the forward voltage drop of the diode increases.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ Forward Voltage changes as Forward Current changes, similar to a diode curve.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.A drop of 1 V to 1.5 V is typical at full rated current for power diodes.^ A drop of 1 V to 1.5 V is typical at full rated current for power diodes.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ It is typically specified at full current.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Dissipated power increases as leakage current increases, which heats up the diode junction.
  • Voltage Multipliers, Inc. - FAQs about Our High Voltage Diodes 19 January 2010 18:22 UTC www.voltagemultipliers.com [Source type: FILTERED WITH BAYES]

Shockley diode equation

.The Shockley ideal diode equation or the diode law (named after transistor co-inventor William Bradford Shockley, not to be confused with tetrode inventor Walter H. Schottky) gives the I–V characteristic of an ideal diode in either forward or reverse bias (or no bias).^ The forward-bias and the reverse-bias properties of the p-n junction imply that it can be used as a diode .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The reverse breakdown region is not modeled by the Shockley diode equation.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The Shockley diode equation models the forward-bias operational characteristics of a p-n junction outside the avalanche (reverse-biased conducting) region.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

The equation is:
I=I_\mathrm{S} \left( e^{V_\mathrm{D}/(n V_\mathrm{T})}-1 \right),\,
where
I is the diode current,
IS is the reverse bias saturation current,
VD is the voltage across the diode,
VT is the thermal voltage, and
n is the .emission coefficient, also known as the ideality factor.^ And n is the emission coefficient , also known as the ideality factor.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The LDC501 has a temperature coefficient of 10 ppm/°C, which is a factor of five better than competing models, making it the ideal controller for precision laser diode experiments.
  • LDC501 - Laser Diode Controller 19 January 2010 18:22 UTC www.thinksrs.com [Source type: Reference]

^ I=I_\mathrm{S} \left( {e^{V_\mathrm{D} \over {n V_\mathrm{T}}}-1} \right)\,, where I is the diode current, IS is a scale factor called the saturation current, VD is the voltage across the diode VT is the thermal voltage and n is the emission coefficient.

.The emission coefficient n varies from about 1 to 2 depending on the fabrication process and semiconductor material and in many cases is assumed to be approximately equal to 1 (thus the notation n is omitted).^ The emission coefficient n varies from about 1 to 2 depending on the fabrication process and semiconductor material and in many cases is assumed to be approximately equal to 1 (thus ommitted).

^ The emission coefficient n varies from about 1 to 2 depending on the fabrication process and semiconductor material and in many cases is assumed to be approximately equal to 1 (thus the notation n is omitted).
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ However, the properties of silicon, as well as those of other semiconductor materials, can be modified during synthesis by the introduction of varying amounts of impurities into the crystalline lattice, a process known as doping (see Figure 2).
  • Olympus FluoView Resource Center: Diode Lasers - Interactive Java Tutorial 19 January 2010 18:22 UTC www.olympusconfocal.com [Source type: Reference]

.The thermal voltage VT is approximately 25.85 mV at 300 K, a temperature close to “room temperature” commonly used in device simulation software.^ The thermal voltage VT is approximately 25.2 mV at room temperature (approximately 25oC or 298K) and is a known constant.

^ The thermal voltage V T is approximately 25.85 mV at 300 K, a temperature close to “room temperature” commonly used in device simulation software.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ Laser diodes are commonly used in optical storage devices and for high speed optical communication.

At any temperature it is a known constant defined by:
V_\mathrm{T} = \frac{k T}{q} \, ,
where .k is the Boltzmann constant, T is the absolute temperature of the p-n junction, and q is the magnitude of charge on an electron (the elementary charge).^ T is the absolute temperature of the p-n junction in kelvins .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ Where q is the magnitude of charge on an electron (the elementary charge ), .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ Here, the quantity q represents the charge of a single electron in coulombs, k is Boltzmann's constant, and T is the diode's temperature in K .
  • The Diode 19 January 2010 18:22 UTC cnx.org [Source type: General]

.The Shockley ideal diode equation or the diode law is derived with the assumption that the only processes giving rise to the current in the diode are drift (due to electrical field), diffusion, and thermal recombination-generation.^ In this equation, v D and i D are the diode voltage and current and V T is the thermal voltage.
  • http://faculty.evansville.edu/ar63/courses/Tutorials/Diode_Modeling_1.html 19 January 2010 18:22 UTC faculty.evansville.edu [Source type: Academic]

^ Shockley diode equation .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The Shockley ideal diode equation or the diode law is derived with the assumption that the only processes giving rise to current in the diode are drift (due to electrical field), diffusion, and thermal recombination-generation.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

.It also assumes that the recombination-generation (R-G) current in the depletion region is insignificant.^ It also assumes that the recombination-generation (R-G) current in the depletion region is insignificant.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ If we assume that, of those electrons injected into the depletion region, all of their energy supplied by the electric field is converted into light, then the frequency of that light is approximately, .
  • Advanced Lab - Photoelectric Effect:Light Emitting Diodes 19 January 2010 18:22 UTC www.physics.gatech.edu [Source type: Academic]

^ Again, this is because at this voltage you are injecting a significant amount of electrons into the depletion region where they recombine with holes and emit light.
  • Advanced Lab - Photoelectric Effect:Light Emitting Diodes 19 January 2010 18:22 UTC www.physics.gatech.edu [Source type: Academic]

.This means that the Shockley equation doesn’t account for the processes involved in reverse breakdown and photon-assisted R-G. Additionally, it doesn’t describe the “leveling off” of the I–V curve at high forward bias due to internal resistance.^ The reverse breakdown region is not modeled by the Shockley diode equation.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ This means that the Shockley equation doesn’t account for the processes involved in reverse breakdown and photon-assisted R-G. Additionally, it doesn’t describe the “leveling off” of the I–V curve at high forward bias due to internal resistance.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The Shockley ideal diode equation or the diode law (named after transistor co-inventor William Bradford Shockley , not to be confused with tetrode inventor Walter H. Schottky ) is the I–V characteristic of an ideal diode in either forward or reverse bias (or no bias).
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

.Under reverse bias voltages (see Figure 5) the exponential in the diode equation is negligible, and the current is a constant (negative) reverse current value of −IS.^ In this equation, v D and i D are the diode voltage and current and V T is the thermal voltage.
  • http://faculty.evansville.edu/ar63/courses/Tutorials/Diode_Modeling_1.html 19 January 2010 18:22 UTC faculty.evansville.edu [Source type: Academic]

^ Figure 3 - zener voltage regulation diodes .

^ Leakage current increases exponentially as the reverse voltage increases.
  • Voltage Multipliers, Inc. - FAQs about Our High Voltage Diodes 19 January 2010 18:22 UTC www.voltagemultipliers.com [Source type: FILTERED WITH BAYES]

.The reverse breakdown region is not modeled by the Shockley diode equation.^ The reverse breakdown region is not modeled by the Shockley diode equation.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ Shockley diode equation .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ This means that the Shockley equation doesn’t account for the processes involved in reverse breakdown and photon-assisted R-G. Additionally, it doesn’t describe the “leveling off” of the I–V curve at high forward bias due to internal resistance.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

For even rather small forward bias voltages (see Figure 5) the exponential is very large because the thermal voltage is very small, so the subtracted ‘1’ in the diode equation is negligible and the forward diode current is often approximated as
I=I_\mathrm{S} e^{V_\mathrm{D}/(n V_\mathrm{T})}
.The use of the diode equation in circuit problems is illustrated in the article on diode modeling.^ Other uses for the Circuit Breaker Diode .
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

^ Because of the diode's nonlinear nature, we cannot use impedances nor series/parallel combination rules analyze circuits containing them.
  • The Diode 19 January 2010 18:22 UTC cnx.org [Source type: General]

^ The 4 MID-plane diodes (FE, FW, BE, BW) are used in a sophisticated ABORT circuit that can automatically abort the PEP-II stored beams.
  • SVT diodes power guide 19 January 2010 18:22 UTC www.slac.stanford.edu [Source type: FILTERED WITH BAYES]

Small-signal behaviour

.For circuit design, a small-signal model of the diode behavior often proves useful.^ Small Signal Diodes (108) .
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ If this circuit were designed to provide a constant or nearly constant current through the diode despite changes in forward voltage drop, it could be used as the basis of a temperature-measurement instrument, the voltage measured across the diode being inversely proportional to diode junction temperature.

^ Often they just want to know how a particular component will behave in a circuit, rather than being interested in device physics or the diode design.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

.A specific example of diode modeling is discussed in the article on small-signal circuits.^ Small Signal Diodes (108) .
  • Zener Diode - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: General]

^ Small Signal Switching Diodes (120) .
  • Diodes 19 January 2010 18:22 UTC www.onsemi.com [Source type: Reference]
  • Small Signal Switching Diodes 19 January 2010 18:22 UTC www.onsemi.com [Source type: Reference]

^ The power dissipated in a diode during reverse recovery can differ greatly between real circuit results and the SPICE model simulation.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

Types of semiconductor diode

.
Figure 7: Typical diode packages in same alignment as diode symbol.
^ Figure 1: v-i relation and schematic symbol for the diode.
  • The Diode 19 January 2010 18:22 UTC cnx.org [Source type: General]

^ A few schematic symbols for diodes are: Figure 1 - schematic symbols for diodes .

^ Semiconductor diodes are symbolized in schematic diagrams such as Figure below .

Thin bar depicts the cathode.
.
Figure 8: Several types of diodes.
^ This type of diode is depicted in figure 1 above.

^ The schematic symbol of the diode is shown in Figure above (b) such that the anode (pointing end) corresponds to the P-type semiconductor at (a).

The scale is centimeters.
There are several types of junction diodes, which either emphasize a different physical aspect of a diode often by geometric scaling, doping level, choosing the right electrodes, are just an application of a diode in a special circuit, or are really different devices like the Gunn and laser diode and the MOSFET:
.Normal (p-n) diodes, which operate as described above, are usually made of doped silicon or, more rarely, germanium.^ A diode made of silicon needs about 0.7V across it in the forward direction ( forward biased ) in order to conduct.

^ LS34, Silicon Epitaxial Planar Diode s, Switching Diode s View more products from this supplier .
  • Diode Manufacturers & Suppliers | Global Sources 19 January 2010 18:22 UTC www.globalsources.com [Source type: General]

^ Light-emitting diode (LED) technology has made everything from traffic lights to flashlights more efficient.
  • Light-Emitting Diode (LED) Display and Device Providers | Business.com 19 January 2010 18:22 UTC www.business.com [Source type: General]

.Before the development of modern silicon power rectifier diodes, cuprous oxide and later selenium was used; its low efficiency gave it a much higher forward voltage drop (typically 1.4–1.7 V per “cell”, with multiple cells stacked to increase the peak inverse voltage rating in high voltage rectifiers), and required a large heat sink (often an extension of the diode’s metal substrate), much larger than a silicon diode of the same current ratings would require.^ ON Semiconductor supplies low-loss and high current schottky diodes and rectifiers.
  • Diodes 19 January 2010 18:22 UTC www.onsemi.com [Source type: Reference]

^ Measuring the diode forward voltage - how?

^ A switching diode is faster than a rectifier (1N400X) but cant handle as much current.
  • E72  Lab - Diodes 19 January 2010 18:22 UTC www.swarthmore.edu [Source type: FILTERED WITH BAYES]

.The vast majority of all diodes are the p-n diodes found in CMOS integrated circuits, which include two diodes per pin and many other internal diodes.^ I'm not planning to add green modules YET. I think we've first gotta sort out all of the other DIODES. Then when we finish everything else we can start with green modules.
  • Diodes Compilation - All Diodes Data In One Thread! - Laser Pointer Forums - Discuss Lasers & Laser Pointers 19 January 2010 18:22 UTC laserpointerforums.com [Source type: General]

^ This type of model is primarily used by circuit designers in circuit simulations where the diode is only one of many electronic components.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

^ Since all the other diodes are named for the sled they were in, it adds a little confusion since the GGW has two good hobbyist diodes in it..
  • Diodes Compilation - All Diodes Data In One Thread! - Laser Pointer Forums - Discuss Lasers & Laser Pointers 19 January 2010 18:22 UTC laserpointerforums.com [Source type: General]

Diodes that conduct in the reverse direction when the reverse bias voltage exceeds the breakdown voltage. These are electrically very similar to Zener diodes, and are often mistakenly called Zener diodes, but break down by a different mechanism, the avalanche effect. .This occurs when the reverse electric field across the p-n junction causes a wave of ionization, reminiscent of an avalanche, leading to a large current.^ A zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is "clamped" to a known value (called the zener voltage ), and avalanche does not occur.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The strength of the depletion zone electric field increases as the reverse-bias voltage increases.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ With increasing forward-bias voltage, the depletion zone eventually becomes thin enough that the zone's electric field can't counteract charge carrier motion across the p-n junction, consequently reducing electrical resistance.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

.Avalanche diodes are designed to break down at a well-defined reverse voltage without being destroyed.^ Zener diodes have a low breakdown voltage, or zener voltage, and can allow reverse current to flow without being destroyed.

^ A zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is "clamped" to a known value (called the zener voltage ), and avalanche does not occur.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ ZENER DIODE A semiconductor P-N junction diode that has a controlled reverse-bias breakdown voltage, and is used to supply (clamp) a specific voltage for other ...
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

.The difference between the avalanche diode (which has a reverse breakdown above about 6.2 V) and the Zener is that the channel length of the former exceeds the “mean free path” of the electrons, so there are collisions between them on the way out.^ V o u t is the reverse breakdown voltage or zener voltage .

^ A zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is "clamped" to a known value (called the zener voltage ), and avalanche does not occur.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ The power dissipated in a diode during reverse recovery can differ greatly between real circuit results and the SPICE model simulation.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

.The only practical difference is that the two types have temperature coefficients of opposite polarities.^ If the pressure is of the opposite “polarity,” the pressure difference across the check valve will close and hold the gate so that no flow occurs.

These are a type of point-contact diode. The cat’s whisker diode consists of a thin or sharpened metal wire pressed against a semiconducting crystal, typically galena or a piece of coal.[7] .The wire forms the anode and the crystal forms the cathode.^ So, if I am right, for a p-MOSFET such as the IRF 520 or 2N7000, the wiring is: ---anode -> |-cathode --drain/gate--source--- or: ---drain/gate--source--anode -> |-cathode--- And what about the voltage threshold of a MOSFET wired as a diode?

.Cat’s whisker diodes were also called crystal diodes and found application in crystal radio receivers.^ Early diodes included “cat’s whisker” crystals and vacuum tube devices (also called thermionic valves ).
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

.Cat’s whisker diodes are generally obsolete, but may be available from a few manufacturers.^ In some cases, where higher voltage is required to the laser diode, separate DC power supply inputs may be available to power the control electronics from a low +5V supply and the laser diode from a higher voltage supply.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Early diodes included “cat’s whisker” crystals and vacuum tube devices (also called thermionic valves ).
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ It adjusts the MID-plane diodes' pedestal currents based on an offline generated "radiation damage coefficient" which is updated very few days.
  • SVT diodes power guide 19 January 2010 18:22 UTC www.slac.stanford.edu [Source type: FILTERED WITH BAYES]

[citation needed]
These are actually a .JFET with the gate shorted to the source, and function like a two-terminal current-limiter analog to the Zener diode, which is limiting voltage.^ We can use a zener diode to build a voltage regulator like this: .

^ The voltage-current graph of a zener diode looks like this: .

^ The Current Limit is the maximum current the Current Source will deliver.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.They allow a current through them to rise to a certain value, and then level off at a specific value.^ Leakage Current: Ideally, when a laser diode driver is turned off, no current flows through the diode.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Fall Time: When the Current Source is disabled, the current level through the diode will fall to residual levels within this time.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ The term 'reverse recovery' refers to a delay in turn-off (i.e., the transition to a high resistance) of a diode when the current through it is reversed from the forward direction to the reverse direction.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

.Also called CLDs, constant-current diodes, diode-connected transistors, or current-regulating diodes.^ This is called Constant Current Mode (or CC mode).
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ In the most ideal form, it is a constant current source, linear, noiseless, and accurate, that delivers exactly the current to the laser diode that it needs to operate for a particular application.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ If laser diode current is used as feedback, the control system will try to keep it constant.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

These have a region of operation showing negative resistance caused by quantum tunneling, thus allowing amplification of signals and very simple bistable circuits. .These diodes are also the type most resistant to nuclear radiation.^ These factors can make the initial turn-on resistance of some very high voltage diodes quite large.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

^ The system is enabled only for the MID-plane diodes since radiation damage is most significant there.
  • SVT diodes power guide 19 January 2010 18:22 UTC www.slac.stanford.edu [Source type: FILTERED WITH BAYES]

^ Talk about the light-emitting diode (LED) is on the lips of most electronic manufacturers these days.
  • Light-Emitting Diode (LED) Display and Device Providers | Business.com 19 January 2010 18:22 UTC www.business.com [Source type: General]

These are similar to tunnel diodes in that they are made of materials such as GaAs or InP that exhibit a region of negative differential resistance. .With appropriate biasing, dipole domains form and travel across the diode, allowing high frequency microwave oscillators to be built.^ I would suggest the Super Digital Appliance Diode which covers digital frequencies and is the best option for computers, monitors, microwaves and televisions.
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

^ A diode made of silicon needs about 0.7V across it in the forward direction ( forward biased ) in order to conduct.

^ The Super High Frequency Circuit Breaker Diode is designed to be placed on your home's circuit breaker box.
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

In a diode formed from a direct band-gap semiconductor, such as .gallium arsenide, carriers that cross the junction emit photons when they recombine with the majority carrier on the other side.^ This increases the voltage barrier causing a high resistance to the flow of charge carriers thus allowing minimal electric current to cross the p-n junction.
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

Depending on the material, wavelengths (or colors) from the infrared to the near ultraviolet may be produced. .The forward potential of these diodes depends on the wavelength of the emitted photons: 1.2 V corresponds to red, 2.4 V to violet.^ Another type of diode that we will use is the light emitting diode, or LED. The LED has similar characteristics to a standard Silicon diode but it has a higher voltage drop, typically between 1 and 2 volts, depending on the color (LED's at higher wavelengths (and hence energies) have higher voltage drops).
  • E72  Lab - Diodes 19 January 2010 18:22 UTC www.swarthmore.edu [Source type: FILTERED WITH BAYES]

^ A spectrum composed of a number of discrete lines corresponding to single wavelengths of emitted or absorbed radiation.

^ So the forward voltage of these diodes is usually 1.5 to 3V. The knee of conduction is quite soft, and so diodes using this don't go from full off to full on, they gradually turn on.

.The first LEDs were red and yellow, and higher-frequency diodes have been developed over time.^ The high powdered All Purpose Diode offers a broader range of protection in the higher frequencies which are present in the new technology in today's modern digital equipment.
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

^ If the voltage across the protected device rises very quickly, the slow turn-on of a clamp diode can result in the voltage across the protected device rising higher than desired, if only for a short time.
  • The Unusual Diode FAQ - IV.33 - Diode Modeling 19 January 2010 18:22 UTC www.avtechpulse.com [Source type: FILTERED WITH BAYES]

^ The value is different for other diode types — Schottky diodes can be as low as 0.2 V and red light-emitting diodes (LEDs) can be 1.4 V or more and blue LEDs can be up to 4.0 V. .
  • DIODE - a knol by Mahesh Nookala 19 January 2010 18:22 UTC knol.google.com [Source type: FILTERED WITH BAYES]

.All LEDs produce incoherent, narrow-spectrum light; “white” LEDs are actually combinations of three LEDs of a different color, or a blue LED with a yellow scintillator coating.^ At this current emission changes from spontaneous (LED like) to stimulated and coherent light is produced.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Project Kits White LED flashlight kit VELLEMAN WHITE LED FLASH LIGHT KIT 1+ £6.19 More Details > > .
  • Search Results 19 January 2010 18:22 UTC www.rapidonline.com [Source type: FILTERED WITH BAYES]

^ Similar High Power led, Available in various colors,CE,FCC& ROHS Approval, high power led/hight power led lighting/power led,...
  • Diodes - Diodes and more 19 January 2010 18:22 UTC www.alibaba.com [Source type: General]

LEDs can also be used as low-efficiency photodiodes in signal applications. An LED may be paired with a photodiode or phototransistor in the same package, to form an opto-isolator.
When an LED-like structure is contained in a resonant cavity formed by polishing the parallel end faces, a laser can be formed. .Laser diodes are commonly used in optical storage devices and for high speed optical communication.^ High-speed Diode s .
  • Diode Manufacturers & Suppliers | Global Sources 19 January 2010 18:22 UTC www.globalsources.com [Source type: General]

^ IMPATT DIODE (IMPact Avalanche and Transit Time diode ) An avalanche diode used as a high-frequency oscillator or amplifier.
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ Diode pumped laser modules High power,Reliable ,Efficient ,Compact ,Long lifetime ,Easy to use...
  • Diodes - Diodes and more 19 January 2010 18:22 UTC www.alibaba.com [Source type: General]

These diodes are used as sensors, heat engines for thermoelectric cooling. .Charge carriers absorb and emit their band gap energies as heat.^ White wall reflects light, no energy absorbed = no heat absorbed = no scorch mark.
  • Laser Flashlight Hack! - Video 19 January 2010 18:22 UTC www.metacafe.com [Source type: FILTERED WITH BAYES]

All semiconductors are subject to optical charge carrier generation. .This is typically an undesired effect, so most semiconductors are packaged in light blocking material.^ Light-Emitting Diode -- A semiconductor diode, made from certain materials (e.g.

.Photodiodes are intended to sense light(photodetector), so they are packaged in materials that allow light to pass, and are usually PIN (the kind of diode most sensitive to light).^ Double-faced tape affixed to the Equipment Diode allows quick and easy application to most non-digital equipment and appliances.
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

^ Grounding with modules and components: Some laser diode packages short either pin of the laser diode to the case, which may connect the pin to earth ground through system hardware.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Feedback Mode: Most laser diode drivers will allow control based on either laser diode current or photodiode current.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.A photodiode can be used in solar cells, in photometry, or in optical communications.^ If photodiode current is used as feedback, the control system will try to keep the photodiode current (and by extension laser diode optical power) constant.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.Multiple photodiodes may be packaged in a single device, either as a linear array or as a two-dimensional array.^ Grounding with modules and components: Some laser diode packages short either pin of the laser diode to the case, which may connect the pin to earth ground through system hardware.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Two rows of pins are referred to as DIP packaging (dual-in-line), while a single row of pins is called SIP packaging (single-in-line).
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

These arrays should not be confused with charge-coupled devices.
Point-contact diodes
These work the same as the junction semiconductor diodes described above, but their construction is simpler. A block of n-type semiconductor is built, and a conducting sharp-point contact made with some group-3 metal is placed in contact with the semiconductor. Some metal migrates into the semiconductor to make a small region of p-type semiconductor near the contact. The long-popular 1N34 germanium version is still used in radio receivers as a detector and occasionally in specialized analog electronics.
A PIN diode has a central un-doped, or intrinsic, layer, forming a p-type/intrinsic/n-type structure. They are used as radio frequency switches and attenuators. They are also used as large volume ionizing radiation detectors and as photodetectors. .PIN diodes are also used in power electronics, as their central layer can withstand high voltages.^ ZENER DIODE A semiconductor P-N junction diode that has a controlled reverse-bias breakdown voltage, and is used to supply (clamp) a specific voltage for other ...
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ IMPATT DIODE (IMPact Avalanche and Transit Time diode ) An avalanche diode used as a high-frequency oscillator or amplifier.
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ Diode pumped laser modules High power,Reliable ,Efficient ,Compact ,Long lifetime ,Easy to use...
  • Diodes - Diodes and more 19 January 2010 18:22 UTC www.alibaba.com [Source type: General]

Furthermore, the PIN structure can be found in many power semiconductor devices, such as IGBTs, power MOSFETs, and thyristors.
.Schottky diodes are constructed from a metal to semiconductor contact.^ ON Semiconductor Unveils new Micro-Packaged Diodes & Semiconductors.....II-14 IXYS Unveils New Diode Range.....II-14 IXYS Unveils Sonic-FRD.....II-14 Fairchild Unveils New Range of Schottky Diodes.....II-14 .
  • Discrete Diodes (MCP-1151) - Global Industry Analysts, Inc. 19 January 2010 18:22 UTC www.strategyr.com [Source type: News]

^ Zener Diode - Fairchild Semiconductor Site Search Contact Us My Fairchild View Shopping Cart Fairchild Worldwide: .
  • Zener Diode - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: General]

.They have a lower forward voltage drop than p-n junction diodes.^ Measuring the diode forward voltage - how?

^ Forward Voltage: A specification of the laser diode.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Forward Voltage is used to determine the minimum DC power input level to a module or component to sufficiently drive the laser diode.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.Their forward voltage drop at forward currents of about 1 mA is in the range 0.15 V to 0.45 V, which makes them useful in voltage clamping applications and prevention of transistor saturation.^ Forward Voltage is used to determine the minimum DC power input level to a module or component to sufficiently drive the laser diode.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Forward Voltage changes as Forward Current changes, similar to a diode curve.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Similar High voltage, Low leakage current, Low forward voltage drop, High current capablility, High reliability...
  • Diodes - Diodes and more 19 January 2010 18:22 UTC www.alibaba.com [Source type: General]

.They can also be used as low loss rectifiers although their reverse leakage current is generally higher than that of other diodes.^ Other uses for the Circuit Breaker Diode .
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

^ Other uses for the Equipment Diode .
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

^ Other uses for the Versatile Digital Diode .
  • EMF DIODES 19 January 2010 18:22 UTC www.webnat.com [Source type: General]

.Schottky diodes are majority carrier devices and so do not suffer from minority carrier storage problems that slow down many other diodes — so they have a faster “reverse recovery” than p-n junction diodes.^ Since all the other diodes are named for the sled they were in, it adds a little confusion since the GGW has two good hobbyist diodes in it..
  • Diodes Compilation - All Diodes Data In One Thread! - Laser Pointer Forums - Discuss Lasers & Laser Pointers 19 January 2010 18:22 UTC laserpointerforums.com [Source type: General]

^ Depending on the laser diode configuration and grounding, one approach may be better than the other.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.They also tend to have much lower junction capacitance than p-n diodes which provides for high switching speeds and their use in high-speed circuitry and RF devices such as switched-mode power supply, mixers and detectors.^ High Density Pump Bars The Diode Laser Pump Bar provides up to 100W of CW optical pump energy in a compact, water-cooled package.
  • 808nm laser diode on Coherent inc. 19 January 2010 18:22 UTC lasers.coherent.com [Source type: Reference]

^ Using a diffrent speed DvD burner change the power?
  • Laser Flashlight Hack! - Video 19 January 2010 18:22 UTC www.metacafe.com [Source type: FILTERED WITH BAYES]

^ Diode pumped laser modules High power,Reliable ,Efficient ,Compact ,Long lifetime ,Easy to use...
  • Diodes - Diodes and more 19 January 2010 18:22 UTC www.alibaba.com [Source type: General]

Super Barrier Diodes
Super barrier diodes are rectifier diodes that incorporate the low forward voltage drop of the Schottky diode with the surge-handling capability and low reverse leakage current of a normal p-n junction diode.
Gold-doped diodes
As a dopant, gold (or platinum) acts as recombination centers, which help a fast recombination of minority carriers. .This allows the diode to operate at signal frequencies, at the expense of a higher forward voltage drop.^ Forward Voltage: A specification of the laser diode.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Forward Voltage is used to determine the minimum DC power input level to a module or component to sufficiently drive the laser diode.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

^ Forward Voltage changes as Forward Current changes, similar to a diode curve.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.Gold doped diodes are faster than other p-n diodes (but not as fast as Schottky diodes).^ China (Mainland) Gold Supplier [Verified Member] Manufacturer Fast recovery diode module MUR20040CT (fast recovery module,diode module,fast recovery diode module) .
  • Diodes - Diodes and more 19 January 2010 18:22 UTC www.alibaba.com [Source type: General]

^ Depending on the laser diode configuration and grounding, one approach may be better than the other.
  • High Performance Laser Diode Drivers and Temperature Controllers 19 January 2010 18:22 UTC www.teamwavelength.com [Source type: Reference]

.They also have less reverse-current leakage than Schottky diodes (but not as good as other p-n diodes).^ ZENER DIODE A semiconductor P-N junction diode that has a controlled reverse-bias breakdown voltage, and is used to supply (clamp) a specific voltage for other ...
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ BLOCKING DIODE A diode used to restrict or block reverse current from flowing backward through a module.
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ If you are using a current controller with a modulation bandwidth less than 100kHz this section may not help you much.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

[8][9] A typical example is the 1N914.
The term step recovery relates to the form of the reverse recovery characteristic of these devices. After a forward current has been passing in an SRD and the current is interrupted or reversed, the reverse conduction will cease very abruptly (as in a step waveform). SRDs can therefore provide very fast voltage transitions by the very sudden disappearance of the charge carriers.
These are avalanche diodes designed specifically to protect other semiconductor devices from high-voltage transients. .Their p-n junctions have a much larger cross-sectional area than those of a normal diode, allowing them to conduct large currents to ground without sustaining damage.^ The body diode of the switch conducts current ...
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ We have found that the current can be much more simply limited by choosing R16 such that the maximum current, roughly 7V/(R16+R1), is less than 50% above the rated operating current of the laser diode, which is basically the most you can crank a laser diode before without killing it.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ If you are using a current controller with a modulation bandwidth less than 100kHz this section may not help you much.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

These are used as voltage-controlled capacitors. .These are important in PLL (phase-locked loop) and FLL (frequency-locked loop) circuits, allowing tuning circuits, such as those in television receivers, to lock quickly, replacing older designs that took a long time to warm up and lock.^ The pass-through design of the socket lets you install long lead diodes (up to 3/4") without trimming.
  • Thorlabs.com - Temperature Controlled Laser Diode Mounts 19 January 2010 18:22 UTC www.thorlabs.com [Source type: FILTERED WITH BAYES]

^ In general when using this system locked to the same frequency day after day, these lasers require almost no adjustments.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ Note that at the -3dB point of the modulation bandwidth of a circuit, the signal is often greatly phase shifted, so all of the locking signals should be far below the cutoff frequency of your current driver.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

A PLL is faster than an FLL, but prone to integer harmonic locking (if one attempts to lock to a broadband signal). .They also enabled tunable oscillators in early discrete tuning of radios, where a cheap and stable, but fixed-frequency, crystal oscillator provided the reference frequency for a voltage-controlled oscillator.^ If DC coupling is selected, then the tuning voltage will be controlled entirely by the voltage at the MOD input.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ If AC is selected, then the center frequency will be controlled by the trimpot, and the voltage at the MOD input will be AC-coupled in.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

Diodes that can be made to conduct backwards. This effect, called Zener breakdown, occurs at a precisely defined voltage, allowing the diode to be used as a precision voltage reference. In practical voltage reference circuits Zener and switching diodes are connected in series and opposite directions to balance the temperature coefficient to near zero. Some devices labeled as high-voltage Zener diodes are actually avalanche diodes (see above). Two (equivalent) Zeners in series and in reverse order, in the same package, constitute a transient absorber (or Transorb, a registered trademark). The Zener diode is named for Dr. Clarence Melvin Zener of Southern Illinois University, inventor of the device.
.Other uses for semiconductor diodes include sensing temperature, and computing analog logarithms (see Operational amplifier applications#Logarithmic).^ ZENER DIODE A semiconductor P-N junction diode that has a controlled reverse-bias breakdown voltage, and is used to supply (clamp) a specific voltage for other ...
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ IMPATT DIODE (IMPact Avalanche and Transit Time diode ) An avalanche diode used as a high-frequency oscillator or amplifier.
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ If you are using a linear broadband amplifier like the CA2832, you will find that you can switch your AOMs at the limit of their specs simply by switching off the input to the amplifier with a PIN diode switch.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

Numbering and Coding schemes

There are a number of common, standard and manufacturer-driven numbering and coding schemes for diodes; the two most common being the EIA/JEDEC standard and the European Pro Electron standard:

EIA/JEDEC

A standardized 1N-series numbering system was introduced in the US by EIA/JEDEC (Joint Electron Device Engineering Council) about 1960. Among the most popular in this series were: 1N34A/1N270 (Germanium signal), 1N914/1N4148 (Silicon signal), 1N4001-1N4007 (Silicon 1A power rectifier) and 1N54xx (Silicon 3A power rectifier)[10][11][12]

Pro Electron

The European Pro Electron coding system for active components was introduced in 1966 and comprises two letters followed by the part code. The first letter represents the semiconductor material used for the component (A = Germanium and B = Silicon) and the second letter represents the general function of the part (for diodes: A = low-power/signal, B = Variable capacitance, X = Multiplier, Y = Rectifier and Z = Voltage reference), for example:
  • AA-series germanium low-power/signal diodes (eg: AA119)
  • BA-series silicon low-power/signal diodes (eg: BAT18 Silicon RF Switching Diode)
  • BY-series silicon rectifier diodes (eg: BY127 1250V, 1A rectifier diode)
  • BZ-series silicon zener diodes (eg: BZY88C4V7 4.7V zener diode)
Other common numbering / coding systems (generally manufacturer-driven) include:
  • GD-series germanium diodes (ed: GD9) — this is a very old coding system
  • OA-series germanium diodes (eg: OA47) — a coding sequence developed by Mullard, a UK company
As well as these common codes, many manufacturers or organisations have their own systems too — for example:
  • HP diode 1901-0044 = JEDEC 1N4148
  • UK military diode CV448 = Mullard type OA81 = GEC type GEX23

Related devices

.In optics, an equivalent device for the diode but with laser light would be the Optical isolator, also known as an Optical Diode, that allows light to only pass in one direction.^ The function of a diode is to allow current in one direction and to block current in ...
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ High Density Pump Bars The Diode Laser Pump Bar provides up to 100W of CW optical pump energy in a compact, water-cooled package.
  • 808nm laser diode on Coherent inc. 19 January 2010 18:22 UTC lasers.coherent.com [Source type: Reference]

^ Home » Directory » Electronics & Semiconductors » Electronic Components » Electronic Display Devices » Light-Emitting Diode (LED) Quickly find manufacturers and distributors of light-emmitting diode (LED) display devices.
  • Light-Emitting Diode (LED) Display and Device Providers | Business.com 19 January 2010 18:22 UTC www.business.com [Source type: General]

It uses a Faraday rotator as the main component.

Applications

Radio demodulation

The first use for the diode was the demodulation of amplitude modulated (AM) radio broadcasts. The history of this discovery is treated in depth in the radio article. In summary, an AM signal consists of alternating positive and negative peaks of voltage, whose amplitude or “envelope” is proportional to the original audio signal. The diode (originally a crystal diode) rectifies the AM radio frequency signal, leaving an audio signal which is the original audio signal, minus atmospheric noise. .The audio is extracted using a simple filter and fed into an audio amplifier or transducer, which generates sound waves.^ (Put in a 1kHz square wave and listen for a 1kHz sound wave) Are you using a dead cell?
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

Power conversion

.Rectifiers are constructed from diodes, where they are used to convert alternating current (AC) electricity into direct current (DC).^ The diode laser current should be fed into the laser enclosure with a BNC or SMA connector, and shielded coax cable (RG-316/U) should be used between this connector and a transistor socket, which can be plugged onto the laser itself.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ By Adrian_KRAZY 1189009052 Reply Spam [+0] Moderate Up Moderate Down Remove 5715037 1 This wont work you cannot operate a LED diode on DC current.
  • Laser Flashlight Hack! - Video 19 January 2010 18:22 UTC www.metacafe.com [Source type: FILTERED WITH BAYES]

^ Modulation facilitates external (DC- or AC-coupled) modulation of the laser current by drawing current away from the diode through a 1K resistor - this is explained in the Libbrecht-Hall article.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

.Automotive alternators are a common example, where the diode, which rectifies the AC into DC, provides better performance than the commutator of earlier dynamo.^ Modulation facilitates external (DC- or AC-coupled) modulation of the laser current by drawing current away from the diode through a 1K resistor - this is explained in the Libbrecht-Hall article.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

.Similarly, diodes are also used in Cockcroft–Walton voltage multipliers to convert AC into higher DC voltages.^ Schottky Barrier Diode SOD-123 with VR 20V DC Reverse Voltage .
  • Diode Manufacturers & Suppliers | Global Sources 19 January 2010 18:22 UTC www.globalsources.com [Source type: General]

^ Modulation facilitates external (DC- or AC-coupled) modulation of the laser current by drawing current away from the diode through a 1K resistor - this is explained in the Libbrecht-Hall article.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ In our locking scheme we generally run the dither output of the locking circuit into the MOD in of this circuit and use AC coupling.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

Over-voltage protection

.Diodes are frequently used to conduct damaging high voltages away from sensitive electronic devices.^ ZENER DIODE A semiconductor P-N junction diode that has a controlled reverse-bias breakdown voltage, and is used to supply (clamp) a specific voltage for other ...
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ IMPATT DIODE (IMPact Avalanche and Transit Time diode ) An avalanche diode used as a high-frequency oscillator or amplifier.
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ Home » Directory » Electronics & Semiconductors » Electronic Components » Electronic Display Devices » Light-Emitting Diode (LED) Quickly find manufacturers and distributors of light-emmitting diode (LED) display devices.
  • Light-Emitting Diode (LED) Display and Device Providers | Business.com 19 January 2010 18:22 UTC www.business.com [Source type: General]

.They are usually reverse-biased (non-conducting) under normal circumstances.^ BYPASS DIODE A diode connected across one or more solar cells in a photovoltaic module such that the diode will conduct if the cell(s) become reverse biased.
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

.When the voltage rises above the normal range, the diodes become forward-biased (conducting).^ BYPASS DIODE A diode connected across one or more solar cells in a photovoltaic module such that the diode will conduct if the cell(s) become reverse biased.
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

^ SCHOTTKY DIODE A diode device that exhibits a low forward voltage drop (0.6V) and fast recovery time.
  • Emitting Diodes,Rectifier,Schottky (Diodes and Rectifiers),Small Signal Diodes,Zener Diode,Diodes - Fairchild Semiconductor Site Search 19 January 2010 18:22 UTC www.fairchildsemi.com [Source type: FILTERED WITH BAYES]

.For example, diodes are used in (stepper motor and H-bridge) motor controller and relay circuits to de-energize coils rapidly without the damaging voltage spikes that would otherwise occur.^ We use a Thorlabs PZT controller which amplifies the output signal from this circuit by a factor of 15 and has its own manual DC offset control.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ The files here describe a diode laser current controller that was designed by Jan Hall's group at JILA. The printed circuit board layout was designed by us at UConn.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ Would one be able to use a blue-ray laser diode, in place of the 16x diode used in this video?
  • Laser Flashlight Hack! - Video 19 January 2010 18:22 UTC www.metacafe.com [Source type: FILTERED WITH BAYES]

.(Any diode used in such an application is called a flyback diode).^ NEW! View industrial laser applications using Coherent Diode Lasers .
  • laser diode on Coherent inc. 19 January 2010 18:22 UTC lasers.coherent.com [Source type: FILTERED WITH BAYES]

^ The Diode Optics Challenge The use of diode lasers is becoming increasingly attractive in a wide range of applications.
  • laser diode on Coherent inc. 19 January 2010 18:22 UTC lasers.coherent.com [Source type: FILTERED WITH BAYES]

.Many integrated circuits also incorporate diodes on the connection pins to prevent external voltages from damaging their sensitive transistors.^ Laser protection features include optional grounding configurations, and the 'TEC Lockout' circuit* (also included in our 14-Pin Butterfly Laser Diode Mounts ) that prevents enabling the laser unless the TEC controller is active.
  • Thorlabs.com - Temperature Controlled Laser Diode Mounts 19 January 2010 18:22 UTC www.thorlabs.com [Source type: FILTERED WITH BAYES]

.Specialized diodes are used to protect from over-voltages at higher power (see Diode types above).^ With this configuration, it is not possible to apply the correct voltage bias across both diodes simultaneously using the TCLDM9 laser diode mount.
  • Thorlabs.com - Temperature Controlled Laser Diode Mounts 19 January 2010 18:22 UTC www.thorlabs.com [Source type: FILTERED WITH BAYES]

^ A $10 laser pointer is nothing close to as powerful as the diode used to burn DVDs.
  • Laser Flashlight Hack! - Video 19 January 2010 18:22 UTC www.metacafe.com [Source type: FILTERED WITH BAYES]

^ We put +/-5V voltage regulators on the board so we could use our usual +/-15V supplies to power the switches.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

Logic gates

.Diodes can be combined with other components to construct AND and OR logic gates.^ Discover new Diode and other Electronic Components ...
  • Diode Manufacturers & Suppliers | Global Sources 19 January 2010 18:22 UTC www.globalsources.com [Source type: General]

This is referred to as diode logic.

Ionizing radiation detectors

In addition to light, mentioned above, semiconductor diodes are sensitive to more energetic radiation. .In electronics, cosmic rays and other sources of ionizing radiation cause noise pulses and single and multiple bit errors.^ [H76] (c) A tiny change in the energy of an electron orbiting the nucleus of an atom, caused by the interaction of the electron with other particles that appear and quickly disappear in "quantum fluctuations".

This effect is sometimes exploited by particle detectors to detect radiation. .A single particle of radiation, with thousands or millions of electron volts of energy, generates many charge carrier pairs, as its energy is deposited in the semiconductor material.^ Particles traveling in a curved path continuously radiate p hotons that carry away some of the particles' energy.

^ [H76] (c) A tiny change in the energy of an electron orbiting the nucleus of an atom, caused by the interaction of the electron with other particles that appear and quickly disappear in "quantum fluctuations".

^ [P88] (j) A class of particles defined by certain properties: leptons are fermions with spin 1/2 that do not carry color charge and that have another property called lepton number that is different for each family.

If the depletion layer is large enough to catch the whole shower or to stop a heavy particle, a fairly accurate measurement of the particle’s energy can be made, simply by measuring the charge conducted and without the complexity of a magnetic spectrometer or etc. .These semiconductor radiation detectors need efficient and uniform charge collection and low leakage current.^ Simply put, a light emitting diode is a very small semiconductor that converts an electric current into visible light or infrared radiation.
  • Light-Emitting Diode (LED) Display and Device Providers | Business.com 19 January 2010 18:22 UTC www.business.com [Source type: General]

They are often cooled by liquid nitrogen. For longer range (about a centimetre) particles they need a very large depletion depth and large area. For short range particles, they need any contact or un-depleted semiconductor on at least one surface to be very thin. The back-bias voltages are near breakdown (around a thousand volts per centimetre). Germanium and silicon are common materials. Some of these detectors sense position as well as energy. .They have a finite life, especially when detecting heavy particles, because of radiation damage.^ The fraction of energy radiated increases with the energy of the particle, and the radiation happens with greater probability for lighter particles than for heavier ones.

Silicon and germanium are quite different in their ability to convert gamma rays to electron showers.
Semiconductor detectors for high energy particles are used in large numbers. Because of energy loss fluctuations, accurate measurement of the energy deposited is of less use.

Temperature measurements

.A diode can be used as a temperature measuring device, since the forward voltage drop across the diode depends on temperature, as in a Silicon bandgap temperature sensor.^ However, since there is no temperature control for these diodes, heat can build up in the junction causing instability.
  • Thorlabs.com - Laser Diode Modules 19 January 2010 18:22 UTC www.thorlabs.com [Source type: General]

^ Current Monitor enables the current to be monitored by reading the voltage across a 5 ohm resistor in series with the laser diode.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ LL41, Silicon Planar Power Zener Diode s For Use in Stabilizing and Clipping Circuits with High Power .
  • Diode Manufacturers & Suppliers | Global Sources 19 January 2010 18:22 UTC www.globalsources.com [Source type: General]

.From the Shockley ideal diode equation given above, it appears the voltage has a positive temperature coefficient (at a constant current) but depends on doping concentration and operating temperature (Sze 2007).^ For low noise performance, a constant current drive with a temperature-controlled mount is recommended.
  • Thorlabs.com - Laser Diode Modules 19 January 2010 18:22 UTC www.thorlabs.com [Source type: General]

^ The user then needs to find a stable operating point in both current and temperature.
  • Thorlabs.com - Laser Diode Modules 19 January 2010 18:22 UTC www.thorlabs.com [Source type: General]

.The temperature coefficient can be negative as in typical thermistors or positive for temperature sense diodes down to about 20 kelvins.^ Lithium is destroyed rapidly (in about 7500 years) at typical nuclear burning temperatures.

Typically, silicon diodes have approximately −2 mV/˚C temperature coefficient at room temperature.

Current steering

Diodes will prevent currents in unintended directions. .To supply power to an electrical circuit during a power failure, the circuit can draw current from a battery.^ The power supplies should be regulated of course, and they should be outside the metal enclosure that houses the current driver.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ Make a switch that connects a power supply to the batteries so you can charge them without disconnecting anything.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ The current supply circuits we have made are actually based on a later version produced by the JILA electronics shop.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

.An Uninterruptible power supply may use diodes in this way to ensure that current is only drawn from the battery when necessary.^ The power supplies should be regulated of course, and they should be outside the metal enclosure that houses the current driver.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ If you are using a current controller with a modulation bandwidth less than 100kHz this section may not help you much.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ We use rechargeable batteries to power our photodiodes.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

.Similarly, small boats typically have two circuits each with their own battery/batteries: one used for engine starting; one used for domestics.^ We use a Thorlabs PZT controller which amplifies the output signal from this circuit by a factor of 15 and has its own manual DC offset control.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ For higher-speed applications one can use a smaller-area photodiode, biased by a battery, - small signals at high frequencies can be amplified with MiniCircuits connectorized amplifiers (ZFL line) - we wire these up on a little piece of prototype circuit board, so there is no special printed circuit board for this.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

^ One can use a very small piece of printed circuit board to solder protection diodes in parallel with the laser diode.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

.Normally both are charged from a single alternator, and a heavy duty split charge diode is used to prevent the higher charge battery (typically the engine battery) from discharging through the lower charged battery when the alternator is not running.^ I have used a resistor, it seems in your video that you just connected the laser diode directly to the battery terminals in the mag light?
  • Laser Flashlight Hack! - Video 19 January 2010 18:22 UTC www.metacafe.com [Source type: FILTERED WITH BAYES]

^ With this configuration, it is not possible to apply the correct voltage bias across both diodes simultaneously using the TCLDM9 laser diode mount.
  • Thorlabs.com - Temperature Controlled Laser Diode Mounts 19 January 2010 18:22 UTC www.thorlabs.com [Source type: FILTERED WITH BAYES]

Diodes are also used in electronic musical keyboards. .To reduce the amount of wiring needed in electronic musical keyboards, these instruments often use keyboard matrix circuits.^ If you're happy with our circuit designs, you might as well just use these and skip all the PCB layout.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

The keyboard controller scans the rows and columns to determine which note the player has pressed. .The problem with matrix circuits is that when several notes are pressed at once, the current can flow backwards through the circuit and trigger "phantom keys" that cause “ghost” notes to play.^ Fluorescence [DC99] (b) In CCDs and infrared arrays-light emission caused by currents through faulty parts of the structure which behave like a light-emitting diode.

.To avoid triggering unwanted notes, most keyboard matrix circuits have diodes soldered with the switch under each key of the musical keyboard.^ One can use a very small piece of printed circuit board to solder protection diodes in parallel with the laser diode.
  • Diode Laser Synopsis - University of Connecticut 3/2000 19 January 2010 18:22 UTC www.phys.uconn.edu [Source type: FILTERED WITH BAYES]

The same principle is also used for the switch matrix in solid state pinball machines.

Abbreviations

Diodes are usually referred to as D for diode on PCBs. Sometimes the abbreviation CR for crystal rectifier is used.[13]

See also

References

External links

Interactive & Animations


Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

See also diode

German

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Diode
Wikipedia de

Noun

Diode f. (genitive Diode, plural Dioden)
  1. diode

Simple English

A diode is an electronic component with two electrodes which a signal can flow between (but thermionic diodes can have one or two more electrodes).

The most common function of a diode is to allow an electric current to flow in one direction and to block it in the opposite direction.

Today, the most common diodes are made from semiconductor materials such as silicon or germanium.

There are many kinds of diode. For example, Schottky Diode, LED (Light Emitting Diode), Photo Diode, Laser Diode, Varactor Diode, Current Regulator Diode, PIN Diode, Tunnel Diode, Step Recovery Diode, IMPATT Diode, etc.

Contents

Types

Types of diode:

  • Silicon diode.
  • Germanum diode
  • Zener diode
  • Photo diode
  • Light emitting diode (LED)
  • Tunnel diode

Types of semiconductor diode

Template:Float begin |- align = "center" | File:Diode | File:Zener diode | File:Schottky diode | File:Tunnel diode |- align = "center" | Diode | Zener
diode | Schottky
diode | Tunnel
diode |- align = "center" | File:LED | File:Photodiode | File:Varicap | File:SCR |- align = "center" | Light-emitting
diode
| Photodiode | Varicap | Silicon controlled rectifier Template:Float end

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Introduction

In the following text you can read about construction, function, influence of temperature and types of diodes.

Construction

The first types of diodes were called Fleming valves. They worked inside a glass tube (much like a light bulb). Inside the glass bulb there was a small metal wire and a large metal plate. The small metal wire would heat up and emit electricity, which was captured by the plate. However, the large metal plate would not heat up enough to emit electricity because it was too big. So, electricity could go in one direction through the tube but not in the reverse direction. Flemming valves are mostly obsolete now, because they have been replaced by semiconductor diodes.

Semiconducting diodes are usually made of two types of semiconducting metals connected to each other. One type of metal has atoms connected together with a few electrons to spare. The other metal has atoms connected together and needs a few electrons to be complete. Because one metal has too many electrons and the other metal has too few, the electricity will flow easily from the metal with too many electrons into the metal with too few. However, electricity will not flow easily in the reverse direction -- from the metal with too few electrons to the metal with too many. Silicon with arsenic dissolved in it makes a good metal with electrons to spare, while silicon with aluminum dissolved in it makes a good metal with too few electrons to be complete. There are actually many types of combinations of metals that will make p-type and n-type semiconductors.

Function of a diode

Positive voltage at p-side

If you give positive voltage to the p-side and negative voltage to the n-side, the electrons from the n-side will want to go to the positive voltage at the p-side and the holes of the p-side will want to go to the negative voltage at the n-side. Because of this, current flow is able to exist. This is called breakdown. The breakdown voltage of a silicon diode is at about 0.7 V. A germanium diode needs a breakdown voltage at about 0.3 V.

Negative voltage at p-side

If you give negative voltage to the p-side and positive voltage to the n-side, the electrons of the n-side go to the negative voltage at the n-side. The holes of the p-side go to the positive voltage at the p-side. So there will not be a current flow between p- and n-side. If you give too much voltage to the diode in negative direction, the diode will be destroyed.

Influence of temperature

When the temperature increases, the voltage, when the breakdown happens, will go down.

Types of diodes

The standard rectifier diode

The standard rectifier diode is the actual original diode. It has different requirements. It should have high current densities in the forward area, and a high barrier permissible temperature. It should also have a minimum passing-voltage and a high cut-off-frequency. You should also have a high blocking voltage, whereby the blocking flows should remain low. Their applications are the whole modern analog and digital electronics. Especially it becomes straightening of changing and turning tension, and to limit power supply voltage used. The diode is often needed for measurement and drive.

The Z-diode

The Z-diode (Zener diode) operates in the direction lock and so the direction of their work area is located in the 3rd Quadrant. In working towards the passage it is like a normal diode. The name comes from Zenereffekt, the man with the name Zener discovered. The term Z-diode is only a shortcut. A Z-diode can vary how high it is doped and then has different properties breakthrough. With a high allocation to the diode it has a low and a small space charge zone. Is it high, it works with Zener \ tunneleffect. At low doping, it has a large breakdown voltage and space charge zone and works with the avalanche effect. For medium-doping is the breakdown voltage 5-8 volts and there are two effects. Z-diodes are best suited to stabilize voltage for circuits with low power consumption. But the limitation of voltage spikes is a possibility to use it. With appropriate Zener voltage they can be used as donors in nominal value of measuring and control technology, or where reference voltages are required. It can also be used as a protective diode.

Top diode and Junction diode

Top diodes are actually the exact opposite of junction diodes. They have a small barrier layer capacity and are also in high-frequency applications up to several GHz. But they must ensure only at low currents and voltages to operate. As a particular example the gold wire germanium diode is mentioned. Junction diodes have a p-n-transition over a large area and are often made of silicon. They are designed for high currents and voltages. Because they have a pretty big barrier layer capacity, they are not suitable for high frequency applications. A specific example of the application is called the power diode.

The Capacity diode

The capacity diode is a semiconductor diode barrier in the direction of running, so does the barrier layer or space charge zone on pn-transition as a capacity. If the voltage on the diode is changing, then the capacity of the barrier will change, too. Then you look at the capacity diode you see the barrier layer capacity is especially great. Because of the capacity variation can be set 3 different p-n-transitions. With a 1:3 ratio, it is a linear transition, in an abrupt 1:6 and 1:30 a hyper-abrupt p-n-transition. They are used as a substitute for rotary capacitors for the swing vote in the district of radios and televisions, and they will also find use in circuits for the generation of frequency modulation.

Step-Recovery-Diode

The symbol of this diode is the usual symbol of a diode with a kind of snag.

It is especially used in circuits with high frequencies up to GHz. The idea is, to work with the current that flows after the polarity was reversed. It has also an intrinsic layer between the p- and the n-layer. After the polarization has changed, there develops a layer without carriers. That means, there is a layer that is almost not conducting. So you can achieve a high slew rate. This diode is used with high gigahertz-frequencies.

pin-Diode

This diode has no special symbol. The construction of this diode is, that there´s not only a pn-junction, but also an intrinsic layer between the n- and the p-layer. This means, this layer is nearly nonconducting. If it´s forward biased, especially at lower frequencies, it has almost the same characteristics as a usual standard diode. But if it runs in reverse direction, there develops two space charge regions with different extensions. Because of this broad space charge region in the i-zone, the i-zone becomes very conductive. The pin-diode is useful for a high block voltage. It´s a quite fast diode and also used at very high frequencies.

Schottky-Diode

The symbol if this diode is the usual symbol with a ‘S’ at the peak.


It consists of a pn-junction with a metal layer, which is oxidized on the n-doped silicon. This metal can be e.g. aluminum or nickel. In forward direction, the threshold voltage is about 0.3 volt. This is about half of the threshold voltage of a usual diode. The function of this diode is that no minority carriers are injected. So, there´s no diffusion capacitance, because there are no carriers, that could diffuse. This explains why this diode is a very fast one. So it is always used, when speed plays a role. The advantage of this diode is, that it is faster, but has otherwise no restrictions and works like a usual diode. The only disadvantage is, it isn´t appropriate in reverse direction.

Tunnel Diode

In the symbol of the tunnel diode there´s a kind of additional square bracket at the end of the usual symbol.


A tunnel diode consists of a high doped pn-junction. That means both, the n- and the p-layer are high doped. Because of this high doping, there is only a very narrow gap, where the electrons are able to pass through. This so called tunnel-effect appears in both directions. After a certain amount of electrons have passed, the current through the gap decreases, until the normal current through the diode at the threshold voltage begins. This causes an area of a negative differential resistance. This diods are used to deal with really high frequencies (100 GHz) and are of course mostly used in the area of the negative differential resistance.

Backwarddiode

The symbol has at the end of the diode a sign that looks like a big I.


This diode has a construction that is similar to the tunnel diode, but the n- and the p-layer aren´t doped as high. It works with small negative voltages, because it has no threshold voltage in the third quadrant. The current increases immediately, there. From this reason, this diode works in most times in this area.


Citable sentences

Up to date as of December 13, 2010

Here are sentences from other pages on Diode, which are similar to those in the above article.








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