What is Schottky Diode?

what is schottky diode?

 What is Schottky diode?It is a type of  diode that has less forward voltage drop than the P-N junction diode and can be used in high-speed switching applications.

In Schottky diode ,p-type semiconductor is replace by metals such as aluminum or platinum. The  schottky diode name is after the scientist Walter H schottky. Schottky diode is also called Schottky barrier diode ,surface barrier diode, majority carrier device, hot-electron diode or hot carrier diode. It is mostly used in radio frequency application.

Construction

When metal such as aluminum or platinum are joined with N-type semiconductor material ,a junction is formed between the metal and semiconductor. This type of junction is known as Metal semiconductor or M-S junction. As result of this junction a barrier or depletion layer is formed which is known as schottky barrier.

Schottky diode can switch on and off very fastely and it is also produced less noise then p-n junction diode. Therefore it is useful in high speed switching power circuits.

When required voltage is applied to the schottky diode ,flow of current started in the forward direction. Due to this flow of current ,a small voltage loss occurs across the terminal of the diode.This loss in voltage is known as voltage drop.Silicon has a voltage drop of 0.6 to 0.7 volts but in schottky diode the voltage loss is 0.2 to 0.3 volts. Therefore it is used less voltage to turn on.

schottky diode

Symbol

symbol

What is Schottky barrier?

Schottky barrier is the depletion layer which is formed the junction of a metal and n- type semiconductor and to flow the electron across the diode potential barrier need to overcome by electron.

The rectifying metal-semiconductor junctions have rectifying schottky barrier and a non-rectifying semiconductor junction have non-rectifying schottky barrier. The value to this barrier depends upon the combination of the semiconductor material and metal.

unbiased schottky diode
forward biased schottky diode

The schottky barrier height of ohmic contact(non-rectifying barrier) is very low and a schottky barrier height of non-ohmic contact (rectifying barrier ) is very high .

In the non-rectifying schottky barrier the barrier height is not enough to form depletion region so the depletion region is negligible ohmic contact diode but in rectifying schottky barrier which is form depletion region so the depletion region is present in the non ohmic contact diode.

The non rectifying metal semiconductor Junction have very low resistance to the electric current whereas the rectifying metal semiconductor junction have very high resistance to the electric current

The rectifying schottky barrier is formed when metal is in contact with the lightly doped semiconductor whereas non-rectifying barrier is formed when a metal is in contact with the heavily doped semiconductor

A ohmic contact has a linear current voltage (I-V )curve whereas the non ohmic contact have a non linear current voltage (I-V )curve.

V-I Curve schottky diode
energy band

Uses

  • It is uses as general purpose rectifier
  • It is widely uses in power supplier
  • It is uses in radio frequency application
  • It is used in logic circuits
  • It is used in detecting signals

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