Punching through device and its integration—Static induction transistor

Static induction transistor (SIT) having a short-channel structure is characterized by small gate capacitance, high transconductance, and nonsaturation current-voltage characteristic. The major mechanism of current transport in SIT is majority-carrier injection due to barrier height control at the intrinsic gate in the channel. When the channel is completely pinched off due to the gate-to-channel built-in voltage in a junction-gate SIT (JSIT), there appears a normally-off SIT. In the forward gate bias operation of JSIT, which is called bipolar mode SIT (BSIT), the switching speed is far more improved from the conventional JSIT. BSIT exhibits saturation current-voltage characteristic. In BSIT, the drain voltage for the onset of current saturation is lower than that of the bipolar transistor and the current density is very high, leading to characteristics of low impedance, high transconductance, and high current gain. Applications of SIT in LSI are discussed especially concentrating on the BSIT. SIT logic circuit (SITL) containing BSIT exhibits short propagation delay time and low power dissipation and is very promising in the future development of VLSI.