A novel GaAs bipolar transistor structure with GaInP-hole injection blocking barrier.

Abstract

GaAs bipolar transistors of different emitter types have been fabricated from MOCVD grown lattice matched Gasub0.5Insub0.5P/GaAs layer structures using carbon for heavy base doping (p equals 2x10high19 cmhighminus3). Besides conventional heterojunction bipolar transistors we also investigated tunneling emitter bipolar transistors having 2 and 5 nm thin GaInP layers between emitter and base, which act as a hole repelling potential barrier in the valence band. Current gains up to 115 have been obtained at collector current densities of 10high4 A/qcm even for this heavy base doping. All devices show an almost ideal output characteristics with large Early voltage and small offset voltage. From the temperature dependence of the collector current a small effective conduction band barrier at the heterointerface is determined which hardly affects electron injection into the base