Schottky Diode

Introduction :

             

• The charge storage problem of P-N junction can be minimize or limited in schottky diodes.
  

• The potential barrier is set with a contact between a metal & semiconductor.
  
  
• The rectifying action is depends on majority carrier only.
  
  
• As the result there are is o excess minority carrier to recombination hence low level of reverse recovery time.
  
  
• These diodes are used as rectifier at a single frequency exceeding 300 MHz to 20 GHz.

Construction:

• A schottky diode is shown in figure.
  
  
• It is a metal semiconductor junction diode without depletion layer.
  
  
• On one side of junction a metal like gold, silicon, platinum is used and other side N type doped semiconductor is used.
  
  
• For protection purpose metal layer is surrounded by gold or silver layer.
  
  
• The metal film forms the positive electrode and semiconductor is the cathode.

Working:

• Operation is due to the fact that the electrons in different material have different potential energy.
  
  
• N type semiconductors have higher potential energy as compare to electrons of metals.
  
  
• When these two are brought together in contact, there a flow of electron in both direction across the metal-semiconductor interface when contact is first made.
  
  
• A voltage is applied to the schottky diode such that the metal is positive with respect to semiconductor.
  
  
• The voltage will oppose the built in potential and makes it easier to current flow.

Advantages :

• Schottky diode turns on and off faster than ordinary P-N junction diode the basic reason behind this is that schottky diodes are based on majority carrier.
  
  
• As there is no minority carrier there is no worry about depletion layer.
  
  
• It has much less voltage overshoot.