INTERFACE STRUCTURES OF INGAAS INGAASP/INGAP QUANTUM-WELL LASER-DIODES GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION ON GAAS SUBSTRATES/

We have studied the effects of substrate misorientation on the growth of strained-layer In0.18Ga0.82As quantum well laser structures with In GaAsP confinement layers and In0.5Ga0.5P cladding layers lattice match ed to a GaAs substrate, Low-temperature photoluminescence (PL) and ato mic force microscopy (AFM) provide evidence of a strong substrate-orie ntation dependence of the interface structure. The surface morphology of the InGaAs quantum well is found to be determined primarily by the underlying InGaAsP confinement layer. Structures grown on exact-(100) oriented substrates exhibit three-dimensional island surface morpholog y, whereas growths on (100) substrates oriented 2 degrees towards [110 ] exhibit high surface roughness, possibly due to step bunching. These observations correlate well with previously reported device performan ce from strained quantum well laser diodes in the InGaAs/InGaAsP/InGaP material system, and can serve as a tool to optimize device performan ce. (C) 1996 American Institute of Physics.