Schottky-barrier-collector transistor

In saturated switching circuits using junction bipolar transistors, charge-storage due to minority injection into the base and collector is undesirable in terms of switching speed. Efficiency and maximum frequency of operation of class "D" amplifiers using bipolar junction transistor is severely limited by storage effects. Although gold doping has been used to decrease minority carrier lifetime, hence the storage time, it is difficult to control and tends to degrade P-N junctions. A bipolar transistor with a Schottky barrier (Metal-Semiconductor Rectifying Barrier) for the collector-base junction and a P-N semiconductor junction for the emitter-base junction has been fabricated. A Schottky barrier does not inject minority carriers from the metal into the semiconductor, while carriers injected into the metal have practically zero lifetime; hence, the Schottky barrier does not exhibit storage effect. Thus, the Schottky barrier collector transistor (S.B.C.T.) does not have any significant storage time when operated in a saturated-switching mode. In addition, the collector being metallic has negligible series resistance with the result that the contribution to saturation voltage due to collector series resistance is eliminated.