Interface structures of InGaAs/InGaAsP/InGaP quantum well laser diodes grown by metalorganic chemical vapor deposition on GaAs substrates

Abstract

We have studied the effects of substrate misorientation on the growth of strained-layer In0.18Ga0.82As quantum well laser structures with InGaAsP confinement layers and In0.5Ga0.5P cladding layers lattice matched to a GaAs substrate. Low-temperature photoluminescence (PL) and atomic force microscopy (AFM) provide evidence of a strong substrate-orientation 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 morphology, whereas growths on (100) substrates oriented 2° towards [110] exhibit high surface roughness, possibly due to step bunching. These observations correlate well with previously reported device performance from strained quantum well laser diodes in the InGaAs/InGaAsP/InGaP material system, and can serve as a tool to optimize device performance.