Crosshatch Pattern on InGaAsP Layers Grown on GaAs0.7P0.3 Substrate by LPE

Abstract
The crosshatch pattern on an InGaAsP layer grown on a (001) 2° off GaAs0.7P0.3 substrate by LPE was investigated in detail. The crosshatch pattern was analyzed by a fast Fourier transformation of surface height profiles and the effects of growth conditions as well as the substrate pretreatment could be clarified. The surface roughness was reduced by substrate polishing. The formation mechanism of a crosshatch pattern is discussed and it is shown that the crosshatch pattern becomes initiated at the aligned dislocation existing on the substrate and is enhanced by a crystal orientation dependence of the growth rate. About an 80-µm wide (001) facet going along the direction appears on a grown surface. This (001) facet is very smooth and may be suitable for visible lasers having a stripe in the direction.