InGaAs/InP double-heterostructure bipolar transistors with near-ideal β versus ICcharacteristic

InGaAs/InP double-heterostructure bipolar transistors (DHBT's) with current gain β ∼ 630 have been realized using gas-source molecular beam epitaxy (GSMBE). These devices exhibit near-ideal β versus I
C
characteristic (i.e., β independent of I
C
) with a small-signal gain
h_{fe} \sim 180
at
I_{C} \sim 2
nA. In comparison, we find
\beta \sim I_{C}^{0.5}
for a high-quality AlGaAs/GaAs HBT grown by OMCVD. The higher emitter injection efficiency at low collector current levels found in the InGaAs/InP DHBT is due to at least a factor 100 smaller surface recombination current.