Hetero-epitaxial InP layers were grown, under the same growth conditions, by metalorganic chemical vapor deposition onto the (001), (111)A and (111)B surfaces of GaAs substrates. The hetero-epilayers were studied by means of transmission electron microscopy, high-resolution X-ray diffraction, low-temperature photoluminescence, and low-temperature photoluminescence excitation. It was demonstrated that good quality InP epitaxial layers could be grown. Because the layers and substrates had the same crystal structure but different lattice parameters (0.56535nm for GaAs and 0.58687nm for InP), accommodation at the interface could occur via the formation of misfit dislocations parallel to the hetero-interface. A marked reduction in the threading dislocation density for the (111) orientation, and a decrease in the full-width at half-maximum values of the X-ray diffraction peaks were obtained. These results reflected a marked crystalline improvement, due to the reduction in dislocation density when using (111)-oriented substrates. The efficient photoluminescence and the full-width at half-maximum of the exciton peak, as compared with that of InP homo-epitaxy, showed that good-quality InP epilayers could be obtained on (111)-oriented GaAs substrates. Strain relaxation was investigated by means of high-resolution X-ray diffraction and low-temperature photoluminescence excitation. A difference between the optical and X-ray diffraction results was attributed to thermoplastic strain which arose from the difference in thermal expansion coefficients between the epilayers and substrates.

A comparative study of heterostructures InP/GaAs(001) and InP/GaAs(111) grown by metalorganic chemical vapor deposition M.B.Derbali, J.Meddeb, H.Mâaref, D.Buttard, P.Abraham, Y.Monteil: Journal of Applied Physics, 1998, 84[1], 503-8