A fully planar heterojunction bipolar transistor

A fully planar heterojunction bipolar transistor (HBT) in the normal emitter-up configuration is reported. The process utilizes a two-step epitaxial deposition with an intervening selective ion implant of bases. A process is described, the aluminum lift-off (ALL) process, with which refractory metal contacts have been used. Large test devices fabricated have dc gains of β = 600.