26 March 2018

What is schottky diode

A Schottky diode is one types of electronic component. A Schottky diode is most widely used in the mixer, logic circuit, radio frequency, rectifier, solar cell etc. This article discusses the symbol of Schottky diode, what is Schottky diode, application, V-I characteristics and advantages and disadvantages of Schottky diode compare to P-N diode.

Symbol of Schottky diode :

                               Schottky diode
The symbol of the Schottky diode is shown in the figure. In Schottky diode, then types of semiconductor act as the cathode while metal acts as an anode. The Schottky diode has an aluminum-silicon junction.

What is a Schottky diode?

A Schottky diode is one types of electronic component. A Schottky diode has an aluminum-silicon junction.

When Schottky diode is forward biased, free electrons in the n-material move towards the Al-n junction and then travel through the metal to constitute the flow of forwarding current. 

Since metal does not have any holes, so the forward current is due to the movement of electrons only, also have no storage charge and no reverse recovery time.

It can, therefore, be said that rectified current flow in a Schottky diode is by the movement of majority carriers only and the diode is also turn of delay caused by recombination is avoided. As such, Schottky diode can switch off much faster compared to p-n junction diode and also have Schottky diode have a high efficiency it is one types of advantages of Schottky diode.

V-I characteristics of Schottky diode : 

The V-I characteristics of the Schottky diode are shown in the figure. Voltage-current (V-I) characteristics of Schottky diode is almost similar to the P-N junction diode characteristics
  • In Schottky diode, the forward voltage drop is very low compared to the similar to P-N junction diode. 
  • The forward voltage drop of Schottky diode is 0.2 to 0.3 volts, It generally made up of silicon. 
  • V-I characteristics of Schottky diode are very sharper compared to the V-I characteristics of the P-N junction diode.
  • As compared to silicon diode the reverse saturation current occurs at a very low voltage.

Advantages and disadvantages of Schottky diode :

Advantages of Schottky diode :
  • High efficiency.
  • This diode has fast recovery time so it can be mostly used in high speed switching application.
  • Low junction capacitance.
  • Low forward voltage drop.
  • It can operate high frequency.
  • Schottky diode produces less unwanted noise than P-N junction diode.
  • High current density.
Disadvantages of Schottky diode :
  • A Schottky diode is more expensive. 
  • They operate at low voltages compare to the P-N junction diode.
  • This diode can't withstand much higher voltage without break down. 
  • These diodes have relatively higher reverse current. 
  • It gets heated up quickly in practice.
Application Schottky diode :

Schottky barrier diodes are mainly used in high power applications as a rectifier because of their high current density and low forward voltage drop characteristic less power is wasted and so they have widely used in some applications. Let we check the applications of Schottky diode one by one below.
  • Voltage clamping and clipping circuit.
  • Low power TTL logic.
  • Rectifier in power supply.
  • As a switching device.
  • Rectify high-frequency signal.
  • Rf mixer and a detector diode.
  • Solar cell application.
  • Low voltage, high current application.
  • RF mixer and a detector diode.
  • Used in logic circuits.