Abstract
The first fabrication and current-voltage characteristics of oxide-confined collector-up heterojunction bipolar transistors (HBTs) were reported. A partially oxidized Al 0.98 Ga 0.02 As layer was introduced between the base layer and the emitter layer to reduce the base leakage current. The current gain and the turn-on voltage of the fabricated HBT were 16 and 1.07 V, respectively.