VERTICAL INTEGRATION OF A GAAS ALGAAS QUANTUM-WELL LASER AND A LONG-WAVELENGTH QUANTUM-WELL INFRARED PHOTODETECTOR/

A short-wavelength (approximately 0.8mum) GaAs/AlGaAs graded-index sep arate-confinement heterostructure quantum-well laser has been monolith ically integrated with a long-wavelength (approximately 8mum) GaAs/AlG aAs multiple-quantum-well infra-red photodetector on a semi-insulating GaAs substrate by molecular beam epitaxy. The vertical integration me thod is used and the combined structure is a pinin structure. Both the laser and detector exhibit excellent characteristics. At room tempera ture, the ridge waveguide laser has an extremely low threshold current of 25 mA and a differential quantum efficiency above 65% with a strip e width of 20mum. The quantum-well detector has a peak response at 8mu m and a responsivity of 0.7A/W.