δ-doping InGaP/GaAs heterojunction bipolar transistor

An InGaP/GaAs heterojunction bipolar transistor with a 50 Angstrom undoped spacer and delta-doping sheet at base-emitter heterointerface is fabricated and studied, A common-emitter current gain of 280 and an offset voltage as small as 55 mV are obtained, respectively. These results shows that high current gain and low offset voltage can be attained simultaneously without the passivation of the emitter-base junction. The experimental results show that the potential spike is reduced by the employment of a delta-doped layer simultaneously. On the contrary, theoretical consideration also shows that the potential spike vanishes by inserting a delta-doping sheet between the emitter-base heterointerface. (C) 1998 Elsevier Science S.A.