InP/InGaAs double-heterojunction bipolar transistors with high speed, gain and current-driving capability
InP/InGaAs double-heterojunction bipolar transistors (DHBTs) have been fabricated with an emitter area of 9 × 9 μm2 using a nonselfaligned process. Small-signal current gain in excess of 400 was obtained. Device measurements given an f1 = 39 GHz which, to the authors' knowledge, is the highest value reported for an InP/InGaAs DHBT. The value of f1 is in excess of 30GHz for a range of current densities from 8 to 100kA cm-2.