Leak Off Current in Transistors

Leak Off Current in Transistors refers to the curent  which passes through the transistor, even when it is switched off and the PN regions are not in forward bias.

Leak-off current in modern transistors is very small.  The leak off current varies inversely with the thickness of the semiconductor layer.  

Leak-off Current is caused by design imperfections in the transistors.  the Leak-off Current is of the order of micro amperes or nano amperes.  The leak-off current is considered to be significant only when the transistor is designed to be of very low power rating.