GAINP ALGAAS/GAINP DOUBLE-HETEROJUNCTION BIPOLAR-TRANSISTORS WITH ZERO CONDUCTION-BAND SPIKE AT THE COLLECTOR/

Al0.11Ga0.89As was used in the base, next to the GaInP collector of a DHBT, to eliminate the conduction band spike. The DHBT's demonstrated high breakdown voltages, BVCEO and BVCBO of 44.5 V and 54.5 V (gain ap proximate to 20), respectively, for a 1-mu m-thick collector doped to 2 x 10(16) cm(-3) with no voltage dependence of the current gain. Magn etotransport measurements were made on the AlGaAs bases and indicated limitations on the maximum practical base doping due to the inferior m inority electron mobility and lifetime when compared with equivalently doped GaAs, Grading in the base from Al0.11Ga0.89As at the collector to Al0.21Ga0.79As at the emitter introduced a quasielectric field in t he base, reduced the base transit time by a factor of similar to 2.5, and improved the gain over ungraded devices with the same average Al c oncentration.