RESONANT-CAVITY INGAALAS/INGAAS/INALAS PHOTOTRANSISTORS WITH HIGH-GAIN FOR 1.3-1.6 MU-M

We describe the characteristics of resonant-cavity heterojunction bipolar phototransistors (RCHPTs) grown on InP substrates. The active layers are part of a Fabry-Perot cavity in which gold is the top reflector and an InGaAlAs/InAlAs quarter-wave stack is the bottom reflector. The stack and active layer thicknesses are such that the absorption is resonantly enhanced by approximately 100% at 1.28-mu-m in one wafer and 1.52-mu-m in another. An enhancement in photocurrent response also of approximately 100% is obtained at resonance. A dc phototransistor current gain of 5000, corresponding to an optical gain of approximately 2500 at resonance, was measured on a three-terminal device in a RCHPT wafer.