An Ebers-Moll model for heterostructure bipolar transistors with tunnel junctions

Abstract

This paper presents an Ebers-Moll model for HBTs and DHBTs in which tunnelling transport plays an important role at the base-emitter (BE) and/or base-collector (BC) junction. Devices of this type include GaAs or InP-based HBTs with abrupt heterojunctions, as well as a number of devices designed intentionally with thin tunnel layers at the B-E or B-C junctions. For these structures, the conventional drift-diffusion formalisms (and numerical simulators based on them) are inadequate. The present model allows a quasi-analytical description of the device characteristics, assuming one dimensional structure. The model is applied here to the study of tunnel emitter and tunnel collector InGaP-HBTs. Forward and reverse Gummel plots can be analysed in relation to the tunnelling characteristics of the junction barriers.