High Current Gain In_(0.49)Ga_(0.51)P/GaAs Heterojunction Bipolar Transistors with Double Spacers Grown by Gas Source Molecular Beam Epitaxy

This paper reports the improved performance of the lattice-matched N-p^(+)-n In_(0.49)Ga_(0.51)P/GaAs heterojunction bipolar transistors(HBTs)with undoped spacers grown by the gas source molecular beam epitaxy.A 600ÅGaAs base doped with beryllium at 3 × 1019cm^(-3) and a 1000Å In_(0.49)Ga_(0.51)P emitter doped with silicon at 3 × 1017cm^(-3) have been grown.On both sides of the base,the 50Åundoped GaAs spacers were grown.Devices with emitter area of 100× 100μm^(2) were fabricated by using selective wet chemical etching technique.The measured results of HBTs reveal cood junction characteristics,and the common-emitter current gain reaches 320 at the collector current density of 280 A/cm^(2).