IMPROVEMENT OF F(T) BY DIPOLE DOPING AT THE COLLECTOR HETEROJUNCTION IN INP DOUBLE HBTS

The authors show clearly how dipole doping at the collector heterojunc tion in an InP/InGaAs double heterojunction bipolar transistor improve s device performance. Specifically, both f(T) and f(MAX) are increased and the DC current-blocking is reduced. Also the DC switching charact eristics, seen in devices with abrupt undoped InGaAs/InP collector het erojunctions, can almost be eliminated by using the dipole doping at t hat interface.