Emitter-Size Effects and Ultimate Scalability of InP:GaInP/GaAsSb/InP DHBTs

Emitter-size effects (ESEs) are experimentally investigated in GaAsSb-based double heterojunction bipolar transistors (DHBTs) with a new InP:GaInP composite emitter. This letter reveals that both the extrinsic base surface recombination and the intrinsic space charge recombination directly under the emitter are effectively suppressed over a wide range of collector current densities by eliminating the type-II conduction band at the emitter-base heterojunction. The reduction of ESEs enables aggressive scaling and suggests that the GaInP/GaAsSb heterojunction could become a key enabling element for sub-100-nm terahertz bandwidth InP/GaAsSb DHBTs.