The Static induction thyristor (SIT, SITh) is a thyristor with a buried gate structure in which the gate electrodes are placed in n-base region. Since they are normally on-state, gate electrodes must be negatively biased to hold off-state.
Static induction transistor (SIT) is a high power, high frequency device. It is a vertical structure device with short multichannel. Being a vertical device, the SIT structure offers advantages in obtaining higher breakdown voltages than a Field-effect transistor (FET). For the SIT, it is not limited by the surface breakdown between gate and drain.
An SIT has:
short channel length
low gate series resistance
low gate-source capacitance
small thermal resistance
high audio frequency power capability
short turn-on and turn-off time, typically 0.25 μs