InP/InGaAs single heterojunction bipolar transistors (SHBTs) have been fabricated using a highly doped InAs emitter cap for a 50% reduction in emitter resistance to allow aggressive lateral scaling to inerease f(MAX). Type I InP SHBTs have been fabricated with 0.25 mum emitter widths and achieve f(MAX) values as high as 478 GHz on a laterally scaled L-E = 1 mum device, and maintain breakdown voltages greater than 4 V.