0.5 THz Performance of a Type-II DHBT With a Doping-Graded and Constant-Composition GaAsSb Base

A type-II GaAsSb Double Heterojunction Bipolar Transistor (DHBT) with an AlInP emitter, doping-graded GaAsSb base, and InP collector has been grown by molecular beam epitaxy. The 0.38 mu m emitter devices have been fabricated by a triple-mesa wet etch process and demonstrated f(T)/f(MAX) = 470/540 GHz at J(C) = 5.1 mA/mu m(2) and V-CB = 0.65 V. This performance is comparable with composition-graded base devices with similar emitter width.