Study on effect of an intermediate buffer layer structure on the growth of GaAs layers on GaP substrates

GaAs layers were grown on 2°-off (100) GaP substrates by metal-organic vapor phase epitaxy with various intermediate buffer layer structures. GaAsP and InGaAs were used for the buffer layers, and their As/P and In/Ga ratios were altered to control their lattice constants. The crystal properties of the GaAs layers were evaluated on the basis of double-crystal X-ray diffraction rocking curves, low-temperature photoluminescence spectra, and etch-pit densities using molten KOH. The results suggested that a GaAs layer is relatively relaxed but contains a greater number of dislocations when the change in the lattice constant of the buffer layer structure is larger. In contrast, a GaAs layer has a smaller number of dislocations but greater lattice deformation when the change in lattice constant is smaller.