Modeling the DC performance of heterostructure-emitter bipolar transistor

A theoretical model related to minority carrier properties was developed to study the DC performance of a heterostructure-emitter bipolar transistor (HEBT) which uses an AlGaAs/GaAs heterojunction only for minority carrier confinement and causes improved emitter electron injection efficiency. In this study, minority carrier properties were described by means of polynominal fit to the previous data. Here, the band-gap shrinkage in heavily doped layers was also taken into account. On the other hand, current gains of 55 and 180 were achieved experimentally for an HEBT with Al0.3Ga0.7As and Al0.5Ga0.5As confinement layers, respectively. It is found that the calculated data were agree with the experimental results. With the reduction of the base width to 0.1 μm, a common-emitter current gain of around 1000 with small offset voltage was confirmed. These results reveal that the HEBT exhibits the feature of simplicity and excellent DC performance.