INGAAS-GAAS PSEUDOMORPHIC HETEROSTRUCTURE TRANSISTORS PREPARED BY MOVPE

In this paper, we will demonstrate two new InGaAs-GaAs pseudomorphic h eterostructure transistors prepared by MOVPE technology, i.e. InGaAs-G aAs graded-concentration doping-channel MIS-like field effect transist ors (FET) and heterostructure-emitter and heterostructure-base (InGaAs -GaAs) transistors (HEHBT). For the doping-channel MIS-like FET, the g raded In0.15Ga0.85As doping-channel structure is employed as the activ e channel. For a 0.8 x 100 mu m(2) gate device, a breakdown voltage of 15 V, a maximum transconductance of 200 mS/mm, and a maximum drain sa turation current of 735 mA/mm are obtained. For the HEHBT, the confine ment effect for holes is enhanced owing to the presence of GaAs/InGaAs /GaAs quantum wells. Thus, the emitter injection efficiency is increas ed and a high current gain can be obtained. Also, due to the lower sur face recombination velocity of InGaAs base layers, the potential spike of the emitter-base (E-B) junction can be reduced significantly. This can provide a lower collector-emitter offset voltage. For an emitter area of 4.9 x 10(-5) cm(2), the common emitter current gain of 120 and the collector-emitter offset voltage of 100 mV are obtained.