NEW ALGAAS/GAAS DOUBLE HETEROSTRUCTURE-EMITTER BIPOLAR-TRANSISTOR PREPARED BY MOLECULAR-BEAM EPITAXY

A new AlGaAs/GaAs double heterostructure-emitter bipolar transistor (DHEBT) prepared by molecular beam epitaxy (MBE) has been demonstrated. Due to the symmetric structure with respect to the base layer, the device would operate as a bi-directional transistor and switch. The common-emitter current gain for up to 18, with an offset voltage smaller than 0.1 V, is obtained. Furthermore, the undersired knee-shaped characteristics and the reachthrough effect observed in the conventional double heterojunction bipolar transistor (DHBT) are avoided. The bi-directional operations of this structure give a significant flexibility in the circuit applications. It is believed that with adequate adjustments on structural parameters, especially in the minimization of the base-collector junction area, a more symmetric and an improved electrical performance may be achieved.