Physics and high speed devices

Abstract

It is shown how an understanding of the physics of nonequilibrium electron transport in III-V semiconductors can usefully be applied to determining the limits of n-p-n InP/In/sub 0.53/Ga/sub 0.47/As heterostructure bipolar transistor device performance. For example, it is seen that nonequilibrium transport in In/sub 0.53/Ga/sub 0.47/As improves static transistor characteristics such as current gain and minimum lateral dimensions. In addition, the fastest bipolar transistors make use of high velocity Gamma -valley nonequilibrium electron transport in In/sub 0.53/Ga/sub 0.47/As. A thin, highly-doped base with an impurity concentration p>10/sup 20/ cm/sup -3/ has a negligible base transit time and collector transit delay dominates the intrinsic response. Ultra-high-speed heterostructure bipolar transistors perform best with small signals and low collector voltages.<>