Modeling and analysis of heterostructure-emitter and heterostructure-base transistors (HEHBTs)

In this article, we report the DC performances of heterostructure-emitter and heterostructure-base transistors (HEHBTs) by theoretical and experimental analysis. For comparison, the devices with abrupt and graded confinement layer are studied. An analytical model related to the elimination of the potential spike and the recombination components of base current is developed to explain the transistor performances. The experimental current gain of about 280 and 120 are achieved for the devices with abrupt and graded confinement layers, respectively. As a result the excellent confinement effect and negligible neutral recombination in confinement layer for the device with abrupt confinement layer, the current gain is high especially at low emitter-base (E-B) bias regime. Further, the valence band discontinuity (ΔEV) and the emitter injection efficiency are increased attributed to the insertion of InGaAs quantum well (QW) at base region. The offset voltages about of 100 mV are obtained resulted from the elimination of potential spike and low InGaAs surface recombination velocity.