GaAs Bipolar Transistor with a Triple-Well Emitter Structure

Abstract

In this paper, we start with the calculation on subbands of the undoped AlGaAs-GaAs triple-well structure by using transfer matrix approach. In order to obtain more accurate solutions, we have considered the influence of the different electron mass within quantum well8 and potential barriers. -The studied stgucture consists of a n+-GaAs, a 30-4 GaAs, a 204 Alo.Q and, subband E20 resonates with subband El0 when V, of 400mV is applied. The transmission resonance spectra (T*T-E,) for 80mV and 400mV external bias are shown in Fig.2(b) and We have also fabricated a GaAs bipolar transistor with a triple-well structure as emitter by molecular beam epitaxy (MBE). The current-voltage characteristics at 140K are shown in Fig.3. Only a negative-differential-resistance (NDR) phenomenon is observed. This is perhaps produced by the large energy difference existing between E20 and El*. The large number of the thermionic electrons, resulted from the higher external electric field, give a significant injection current and lead to a negligible resonant-tunneling effect in the transport properties. With a suitable parameter adjustment, this transistor will be more attractive in the design of quantum-functional devices. (c>*