The InP/GaAsSb type-H heterostructure system and its application to high-speed DHBTs and photodetectors: physics, surprises, and opportunities (INVITED)

The InP/GaAsSb/InP "type-II" heterostructure system is of interest for high-speed devices such as photodetectors and double heterostructure bipolar transistors (DHBTs) because its band alignment enables the straightforward injection of electrons from a ~0.72 eV p-type GaAsSb layer into n-type InP without any need for interface grading. We briefly review the salient features of the InP-GaAsSb system, and consider some of the surprising device characteristics encountered in InP/GaAsSb -based devices. In several respects, the InP/GaAsSb system is shown to offer very appealing opportunities for the development of high-speed NpN DHBTs with ultrathin base and collector layers