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Why a Schottky diode is faster than a p-n junction diode?
Abhirupmukherjee69
Schottky diode is major charge carrier device. It has no minor charges to recover when device goes on to off or vice versa.
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∙ 12y ago
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Difference between Schottky Barrier Diodes and PN junction diodes?
Difference between Schottky Barrier Diode and P-N Junction Diode is as following...Schottky Diode1) Usually using the aluminum metal which is trivalent element. 2) Depletion layer is thinner than the p-n junction diode.3) Forward threshold voltage is smaller than p-n junction diode(0.1V).4) The junction capacitance is lower than p-n junction diode.P-N Junction Diode1) Trivalent impurity is added to the pure silicon structure. 2) Depletion layer is wider than Schottky diode.3) Forward threshold voltage is higher than Schottky diode(0.6V)4) The junction capacitance is higher than Schottky diode.
Is forward voltage drop of schottky diode more than tunnel diode?
Yes, the forward voltage drop of a Schottky diode is usually more than the forward voltage drop of a tunnel diode. A Schottky diode voltage drop is between approximately 0.15 to 0.45 volt. The interesting thing that makes a tunnel diode different from other diodes is its "negative resistance region" with a "peak current" around 0.06 volt and a "valley current" around 0.30 volt.
Different between schottky diode and zener diode?
pn junction diode conducts current in one directions where as the zener diode conducts in both the directions. large current flow damage the PN junction diode but zener diode conducts eventhough there is a large current........
What is a substitute for a germanium diode?
There is no exact substitute for a germanium diode, except another germanium diode. However if the only concern is to get a lower forward voltage drop than that of a silicon diode (0.7V), then a schottky barrier diode may be a suitable replacement as its forward voltage drop (<0.1V) is even lower than that of a germanium diode (0.2V).
What are Schottky Barrier Diodes?
Good question, and one for us "older timers". First, let's talk about a "standard" silicon diode. These are fairly simple semiconductors with a single junction of P/N doped silicon. Sand if you will, with a little help... The Schottky diode is named after the inventor, Walter Schottky and is well known for having an extremely low forward voltage drop. Silicon junctions typically have a Vf (forward voltage) of about 0.63 volts at the point they begin to conduct current. This can easily rise up to 0.7 or even 1.0 Volts for large, high current diodes but this is mainly due to the Vf of the junction, plus resistive losses due to the high currents. But here, we'll focus on small signal diodes, those used for switching and low currents, in the hundredths of amps or 10mA. The Schottky junction is designed differently and uses a "Schottky barrier", or metal-to-semiconductor junction rather than the typical semi-to-semi conductor PN junction. The end result is a much lower Vf of around 0.15 up to 0.5V. This compares with the ubiquitous germanium diode with a Vf of 0.2V and because of it's low Vf, was very useful in the "diode radio" where a much lower RF power was needed to reach the conduction voltage and thus rectify an AM signal, and in combination with a high impedance headphone, allowed hearing radio stations, using no external power. Many people built their own and required winding antenna coils of hundreds of turns of tiny wire. However, Si-Si (silicon to silicon) junctions other than having a much higher Vf, also take much longer to block a reverse current after having been conducting a forward current. This is also called the recovery period and ranges in the 100's of microseconds which is fast, but slow when compared with modern switching power supplies (for example), which use frequencies into the hundreds of kHz and thus need to switch faster than a silicon diode can recover and block the current. Thus results in a large amount of power dissipation in the diode and makes the power supply less efficient. The Schottky diode, has the two important qualities needed in such uses: first, it's Vf is low reducing the power dissipation when conducting. Second, they're much faster at recovering and thus dissipate much less power during the recovery phase, when the diode is conducting "backwards". The physics involved are beyond the scope of this question, but to summarize: Schottky diodes differ from silicon diodes by using a different type of junction; a metal to Si or "barrier junction" and, have a lower Vf and faster recovery speed. They also cost a lot more than an ordinary diode, like a 1N4001 diode/rectifier. The term "rectifier" simply means a diode generally has enough current carrying ability to be used in a power supply to convert AC into DC. Finally, Schottky diodes, while having attractive capabilities, also have some significant limitations making them less usable in other applications. A main limitation is the Vr or reverse voltage rating, or the voltage that the diode can block without being forced to conduct, typically less than 50V and also "leaking" more current when blocking than an Si diode. Using an example of a 1N4001, it has a Vr rating of 50V, which is the lowest "grade". But also available are the same diodes, with better performance. The 1N4002 has a Vr of 100V, the 1N4003 200V, 1N4004 400V, going up to the 1N4007 with 1000V Vr. These voltages would totally destroy the Schottky diode's ability to block reverse current. But then too, the 1N400x diodes are much slower and cannot be used in high speed circuits like the Schottky diode can. Actually diodes conducts as soon as a current flow is possible and follow an exponential curve whereby eventually any more current flow will not appreciably increase the voltage drop. This empirical voltage drop can be assumed to be ~.7v or~.6v since the current flow will make a difference in voltage drop. This forward voltage drop can be assumed to be 6v to .7v or higher depends on current flow.
What is a Shockley diode?
An ordinary semiconductor diode uses a P-N junction, but when reverse biased it takes a period of time to remove the current carriers from that junction to create the depletion region that blocks reverse conduction. A Shockley diode instead uses a P semiconductor-metal junction, which removes the current carriers much faster from the semiconductor allowing the device to switch much faster. It also has a much lower forward bias voltage than an ordinary diode. In many ways it is similar to the previous point contact diodes (a piece of semiconductor like galena or germanium with a metal "cat's whisker" point contact) in operation, but is more reliable and easier to mass produce.
What is the purpose of an cathode and an anode in a diode?
The cathode and anode are simply two terminals of a semi-conductor junction. In a normal diode, forward bias occurs when the anode is more positive than the cathode.
Why diode dose not allow to set voltage more than 0.7volts across it?
The barrier potential of the silicon diode is 0.7v if the applied voltage across it is more than this voltage then PN-junction of the diode breaks, once pn-junction breaks the voltage across the diode is constant, since it breaks at 0.7 this voltage will be constant and not exceed for any further increase in applied voltage -inform.mayaprasad@gmail.com The voltage across junction will only exceed from 0.7 volt (for silicon diode) in the case of reverse biasing the applied total voltage will appear across p-n junction. ANSWER: .7 VOLTS is an arbitrarily chosen number since a diode any diode have an exponential curve V vs I . This number is chosen when using a diodes but there are times when a greater or lesser voltage is chosen to reflect the application and the current trough the diode determine that. Example a diode gate diode will be chosen as .6 volts rather then .7v and a heavy conducting rectifier may have .8 volt to reflect closely the true value of the diode drop during real conditions
Why schottky is called hot carrier diode?
Because the energy of electrons transfer from semiconductor to metal side have more energy than the fermi energy of electrons in metal side. That's why these are called hot carrier diodes
What are the advantages and disadvantages of pn junction diode?
A junction diode is very useful serving as a rectifier, a switch, or a voltage reference, in an electronic circuit. Switch/rfectifier: the diode acts like a wire when the applied forward bias is above 0.6 V and like an insulator when the bias is reverse but less than the breakdown voltage. The diodes are ubiquitous in the ESD-protect circuit of an input of an electronic circuit. When the reverse bias is high enough, the diode starts to conduct again. However, the action is rather abrupt, meaning a change in 0.1 V increases the reverse current by orders of magnitude. The diode (reverse) voltage seems to have been pinned, regardless of the current henceforth, hence a voltage reference. Also, the pn junction acts like a poorly-insulated capacitor, normally in the reverse-bias region, but acts a capacitor nonetheless, so the designer has one more option to use. The junction diode can serve as an on-chip thermometer after calibration. The junction reverse current is very sensitive to the junction temperature. One unintentional usage is as an impurity sensor. The ideality factor in the forward-bias region is very sensitive to impurity during the fabrication and after passivation. The fact that the pn junction needs to be charged and discharged to realize the switching function, causes a delay in action. This delay can be undesirable to high-speed operations. In voltage referencing, the diode can be over-stressed during breakdown. The pn junction can be thermally destroyed in an avalanche action. The result is a an unintentional permanent short circuit. Since the diode requires a finite voltage level to turn on, this overhead of 0.5V is a headache to a designer who may be using a power supply of 1.8V or lower. Schottky-barrier diodes are not always available to reduce this overhead.
What Is significance of schottky transistor in TTL gates?
A diode in general lets current flow more in one direction than the other. This can be used in many configurations in an electronic circuit, with one of the more common uses in memory and decision making circuits. With more of our electronic devices running on batteries, manufacturing processes are finally realizing that people will probably buy the device that has a longer battery life over other considerations. Wikipedia contributors contend that the metal-semiconductor junction switches faster and operates at lower voltage.
What is transistor action?
The transistor has three regions, emitter,base and collector. The base is much thinner than the emitter while the collector is wider than both. However for the sake of convenience the emitter and collector are usually shown to be of equal size. The transistor has two pn junctions that means it is like two diodes. The junction between emitter and base may be called emitter-base diode or simply the emitter diode.The junction between base and collector may be called collector-base diode or simply collector diode. The emitter diode is always forward biased and the collector diode is always reverse biased.
