Quasiplanar GaInP/GaAs heterojunction bipolar transistors (HBTs) with
selective regrowth of the collector contact are reported. Such devices
have a planar surface topology which should allow large scale integra
tion. The multilayer HBT structure and the selective regrown collector
contact are realised by chemical beam epitaxy (CBE). Cutoff frequency
and maximum oscillation frequency of 30 and 25 GHz, respectively, hav
e been obtained for devices with 2 x 15 mum2 emitter-base junction are
a.