In a power control circuit, power semiconductor devices are employed as ON/OFF switches.

Types of power semiconductor devices


  1. Standard (or) General purpose diode 
  2. Fast recovery diode 
  3. Schottky diode


  1. SCR – Silicon controlled rectifier  
  2. GTO- Gate turn-off thyristor 
  3. SITH – Static induction thyristor
  4. RCT – Reverse conducting thyristor 
  5. GATT – Gate associated Turn-off Thyristor


  1. BJT- Bipolar Junction transistor
  2. MOSFET – Metal oxide semiconductor field effect transistor 
  3. IGBT – Insulated gate bipolar transistor 
  4. SIT- Static induction transistor

Power Diodes 

  A power diode is a two terminal PN-junction diode (Anode and Cathode). Power diodes are needed in the greater part of the force converters. Power diode is uncontrolled gadget . A low-power diode, called signal diode, is a PN-junction diode. A powerful diode, called power diode, is additionally a PN-junction diode however with constructional includes to some degree not quite the same as a sign diode. Signal diode don’t have an additional layer which is utilized in power diode to expand its voltage withstand limit. Power diode have enormous force rating with extra layer acquainted with increment its voltage rating . so power diode have more thickness as contrast with signal diode. 
Power semiconductors additionally contrast in development from signal semiconductors .
The voltage, current and force evaluations of force diodes and semiconductors are a lot higher than the relating appraisals for signal gadgets. Moreover, power gadgets work at lower exchanging speeds while signal diodes and semiconductors work at higher exchanging speeds. Force semiconductor gadgets are utilized broadly in power electronic circuits. A few utilizations of force diodes use as freewheeling diodes, ac to dc change and so forth, 
A PN intersection shapes the fundamental structure square of all force semiconductor gadgets. A PN junction is formed when p-type semiconductor is brought in metallurgical, or physical, contact with n- type semiconductor. A P-region has greater concentration of holes whereas N-region has more electron- concentration. In P-region, free holes are called majority carriers and free electrons minority carriers. In N-region, free electronics are called majority carriers whereas free holes are called minority carriers.
When physical contact between P and N regions is made, free electronics in n material diffuse acrossthe junction into p material. Diffusion of each electron from n to p, leaves a positive charge behind in the N-region near the junction.

Types of power semiconductor devices

Similarly, diffusion of each hole from p to n, leaves a negative charge behind in the P-region near the junction. Across the connection, these charges create an electric field


Types of power semiconductor devices

Some electrons and holes are recombination across the junction. On each side of the junction, opposite charges form stationary ions. The depletion zone (or space charge zone) is an area that extends into both the p and n semiconductor layers. The width of the depletion region (or) depletion layer is 5 x 10-4mm. The potential difference across the depletion region is 0.7 V for silicon and 0.3 V for germanium

When the positive terminal of a battery is connected to the anode (p-type) and the negative terminal to the cathode, the battery is said to be “p-type” (n-type),

Types of power semiconductor devices

The PN junction is forward biased and the diode conducts. Positive terminal of the battery sucks electrons from p-material leaving holes there. These holes travel through p material towards the negative charge at PN junction and thus neutralize partly this negative charge. Similarly negative terminal of the battery injects electrons into n layer. These electrons move through n material, reach the PN junction thereby neutralizing partly the positive charge. As a result, width of the depletion region gets reduced. 

The PN junction is reverse biassed when the negative terminal of a battery is connected to the anode (p-type) and the positive terminal to the cathode (n-type). The width of the depletion layer increases. A rise in junction temperature also decreases width of depletion layer. As the barrier potential depends on width of the depletion layer, the barrier potential decreases with rise in junction temperature. Under the reverse biased condition a small reverse or leakage current (micro or milli ampere) flows and this leakage current increases slowly in magnitude with the reverse voltage until the avalanche or zener voltage is reached
Types of power semiconductor devices

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