High-current InGaAsP-InP phototransistors and some monolithic optical devices

High-gain InGaAsP/InP heterojunction phototransistors (HPT's) have been fabricated by a liquid-phase epitaxial (LPE) technique. A collector current as high as 170 mA has been achieved at a 2-V bias and a 155-µW incident-light power. The optical gain is 1180. A monolithic optical device has been constructed in a InGaAsP/InP system which includes the HPT and a double heterojunction (DH) light-emitting diode (LED). The monolithic optical device is designable as an optical switching and an optical bistable or a light amplification device by controlling positive feedback between the HPT and the LED. A light amplification system comprised of a discrete InGaAsP/InP laser diode and a high-current HPT, has exhibited incoherent-coherent conversion with a positive amplification.