Scaled AlInAs/InGaAs and InP/InGaAs heterostructure bipolar transistors

The authors report on Al/sub 0.48/In/sub 0.52/As/In/sub 0.53/Ga/sub 0.47/ and InP/In/sub 0.53/Ga/sub 0.47/As HBTs (heterojunction bipolar transistors), which demonstrate near-ideal lateral scaling and ultrahigh-speed performance. Abrupt emitter-base junction are used to realize high-energy electron injection and nonequilibrium transport in the base and collection depletion region. Current gains of beta =162 and 122 have been realized in AlInAs/InGaAs transistors with emitter stripe widths of 50 and 0.6 mu m, respectively. Microwave characteristics of the InP/InGaAs HBTs show and f/sub T/=165 GHz, while preliminary results of the AlInAs/InGaAs devices show f/sub T/=72 GHz, which is limited by the parasitics. Also demonstrated is the first successful high-speed scaling of III-V HBTs by achieving f/sub T/>100 GHz in transistors with emitter stripe widths of less than 0.6 mu m. The high performance is due to the large conduction band Gamma -L (0.55 eV) and Gamma -X (1.15 eV) separation in the InGaAs base and collector.