The first Al0.18Ga0.34In0.48P/GaAs/Ga0.52In0.48P double heterojunction
bipolar transistors grow by metal organic vapour phase epitaxy are re
ported. They exhibit a current gain of 110 at high collector-emitter v
oltage and a small offset voltage of 30mV. The addition of Al to the e
mitter has not adversely affected the quality of the emitter-base inte
rface.