An abrupt InP-GaInAs-InP DHBT

We report on the performance of abrupt InP-GaInAs-InP double heterojunction bipolar transistors (DHBTs) with a thin heavily doped n-type InP layer at the base-collector interface. The energy barrier between the base and the collector was fully eliminated by a 4-nm-thick silicon doped layer with N/sub D/=3×10/sup 19/ cm/sup -3/. The obtained f
_T
and f
_max
values at a current density of 1 mA/μm
²
are comparable to the values reported for DHBTs with a grade layer between the base and the collector.