MILLIMETER-WAVE INP INGAAS HETEROJUNCTION BIPOLAR-TRANSISTORS WITH A SUBPICOSECOND EXTRINSIC DELAY-TIME/

We report the microwave characteristics of InP/InGaAs heterojunction b ipolar transistors (HBTs) using a carbon-doped base grown by chemical beam epitaxy (CBE). An extrinsic delay time of 0.856ps was achieved by nonequilibrium transport in a very thin base layer and extremely smal l emitter parasitic resistance through the use of silicon delta-doping in the emitter ohmic contact layer. To our knowledge, this is the sho rtest extrinsic delay time of any bipolar transistors reported. This r esult indicates the great potential of InP/InGaAs HBTs for application s requiring a very large bandwidth.