Transport theory of the double heterojunction bipolar transistor based on current balancing concept

摘要

The effect of the twohyphen;interface conductionhyphen;band spikes of a double heterojunction bipolar transistor on the current transport was theoretically studied. The model was based on the currenthyphen;balancing concept at both the emitterhyphen;base and basehyphen;collector heterojunctions. The analytical expressions for the currenthyphen;voltage characteristics and the offset voltage are derived and relate to material parameters. It is found that the backhyphen;andhyphen;forth bouncing of carriers between two potential spikes and the associated recombination loss represented by an important parameter Dgr;E0play an important role in determining the transistor characteristics. The theory also reveals that in order to eliminate the offset voltage of a double heterojunction bipolar transistor, the emitter and the collector must have the same area, the electron injection efficiency at the basehyphen;collector junction must be made close to unity, and the potential spike energy Dgr;E1must be smaller than Dgr;E0.