Epitaxial Base Layers For Heterojunction Bipolar Transistors

Abstract

An exemplary embodiment of the present invention provides a heterojunction bipolar transistor comprising an emitter, a collector, and a base. The base can be disposed substantially between the emitter and collector. The base can comprise a plurality of alternating type-I and type-II layers arranged to form a short period super lattice. The type-I layers can have a band-gap that is narrower than the band-gap of the type-II layers. At least one of the type-I layers and the type-II layers can consist essentially of a quaternary material.