In a power control circuit, power semiconductor devices are employed as ON/OFF switches.
- SCR – Silicon controlled rectifier
- GTO- Gate turn-off thyristor
- SITH – Static induction thyristor
- RCT – Reverse conducting thyristor
- GATT – Gate associated Turn-off Thyristor
- BJT- Bipolar Junction transistor
- MOSFET – Metal oxide semiconductor field effect transistor
- IGBT – Insulated gate bipolar transistor
- SIT- Static induction transistor
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
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),
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.