what is tunnel diode?

Question

wikipedia answer will not do.i want the answer with detail

Answer 1

The question you are looking for is what on quantum tunneling effec and reference #1 has the quantum explanation.
Wiki is not that bad. If you want more get some original G. Gamow papers.
(Tunnel diodes used in very high switching.
For more information see references. 2,3)

Answer 2

A tunnel diode is a type of semiconductor that is capable of very fast operation, well into the microwave frequency region, made possible by the use of the quantum mechanical effect called tunneling.
These diodes have a heavily doped p–n junction only some 10 nm (100 Å) wide. The heavy doping results in a broken bandgap, where conduction band electron states on the n-side are more or less aligned with valence band hole states on the p-side.The highest frequency room-temperature solid-state oscillators are based on the resonant-tunneling diode.There is another type of tunnel diode called a metal–insulator–metal (MIM) diode, but present application appears restricted to research environments due to inherent sensitivities.There is also a metal–insulator–insulator–metal MIIM diode which has an additional insulator layer. The additional insulator layer allows "step tunneling" for precise diode control.


https://www.electrikals.com/

Answer 3

Re: What is the usefulness of a tunnel diode?

A conventional diode conducts in the forward direction when forward biased in excess of the junction voltage (around 0.7 V for a silicon diode, around 0.3 V for a germanium diode). A diode will also conduct in the reverse direction when the reverse voltage exceeds the reverse breakdown voltage. (Diodes in which this reverse breakdown voltage is carefully controlled to allow them to act as voltage references are called Zener diodes).

Conventional diodes have a nonlinear I-V characteristic, but the slope of the curve is always positive. That is to say, the local slope R= dI/dV is positive. This a "positive resistance" characteristic. A tunnel diode is a specially built diode that features a "negative resistance" characteristic at very low forward bias voltages. That means that for some range of voltages, the current decreases with increasing voltage. The "tunneling" is a quantum mechanical effect whereby electrons "tunnel" through a very thin depletion region.

The tunnel diode is used in extremely high frequency (multi-GHz) and high speed applications such as amplifiers for satellite communications, as described in this more comprehensive discussion describing the history and application of the tunnel diode in satellite applications.

The tunnel diode has not found widespread use in general applications because circuit design involving the tunnel diode is a bit tricky. In fact, until I did a little Web searching, I did not even realize that these devices were still in use. The reason for their lack of popularity is that the tunnel diode is a "one-port" device, making isolation between input and output difficult. Furthermore, the performance of conventional silicon transistors have caught up for very high frequency applications, and the use of the tunnel diode is on the decline.

Answer 4

A tunnel diode or Esaki diode is a type of semiconductor diode which is capable of very fast operation, well into the microwave region GHz, by utilizing quantum mechanical effects.

It was named after Leo Esaki, who in 1973 received the Nobel Prize in Physics for discovering the electron tunneling effect used in these diodes.

Answer 5

A Tunnel Diode is a PN junction that exhibits the negative resistance between two values of forward voltage (i.e. between peak point voltage And valley point voltage)

If semiconductor diode is heavily doped with impuritise it exhibits negetive resistance (i.e. Current decreases in increase voltage)
in certain region in the forward direction

tunnel diode is used as an oscillator


In 1958, Leo Esaki, a Japanese scientist, discovered that if a semiconductor junction diode is heavily doped with impurities, it will have a region of negative resistance. The normal junction diode uses semiconductor materials that are lightly doped with one impurity atom for ten-million semiconductor atoms. This low doping level results in a relatively wide depletion region. Conduction occurs in the normal junction diode only if the voltage applied to it is large enough to overcome the potential barrier of the junction.

In the TUNNEL DIODE, the semiconductor materials used in forming a junction are doped to the extent of one-thousand impurity atoms for ten-million semiconductor atoms. This heavy doping produces an extremely narrow depletion zone similar to that in the Zener diode. Also because of the heavy doping, a tunnel diode exhibits an unusual current-voltage characteristic curve as compared with that of an ordinary junction diode.

The three most important aspects of this characteristic curve are (1) the forward current increase to a peak (IP) with a small applied forward bias, (2) the decreasing forward current with an increasing forward bias to a minimum valley current (IV), and (3) the normal increasing forward current with further increases in the bias voltage. The portion of the characteristic curve between IP and IV is the region of negative resistance.

Tunnel diodes exploit a strange quantum phenomenon called resonant tunneling to provide interesting forward-bias characteristics. When a small forward-bias voltage is applied across a tunnel diode, it begins to conduct current. As the voltage is increased, the current increases and reaches a peak value called the peak current (IP). If the voltage is increased a little more, the current actually begins to decrease until it reaches a low point called the valley current (IV). If the voltage is increased further yet, the current begins to increase again, this time without decreasing into another "valley."

Answer 6

A tunnel diode has negative resistance--that is as the voltage across it rises, the current thru it also rises until a certain point where additional voltage causes a sudden sharp drop in current. thus it can be used as a switch,amplifier,oscillator, etc

Answer 7

This works on tunneling effect, that is difficult to understand.