Epitaxial growth of single crystal Cd 1- xZn xS layers on (111) GaAs substrates using the close-spaced geometry

Abstract

Single crystal Cd 1- x Zn x S layers have been epitaxially grown on (111)GaAs substrates by a vapour phase chemical transport method using the close-spaced geometry and H 2 as a transport agent. The usefulness of the technique for growing layers with a given controlled composition was systematically investigated up to a ZnS molar fraction of about 0.65. Results obtained with sources made by mechanical mixtures of CdS and ZnS powders and with solid solution sources were analyzed and discussed. Composition gradients in the direction of the c-hexagonal axis were observed in both cases but with different sign. Crack free layers with an uncertainty Δ x=±0.015 in the composition near the film—substrate interface were obtained using mechanical mixture sources.