Growth Hillocks and Crystal Structures in Heteroepitaxial CdS Deposited on GaAs

Abstract

CdS layers were grown on {111} faces of GaAs in an atmosphere of hydrogen gas by evaporation method. Deposition temperatures were from ∼720°C to ∼860°C. Characteristic growth patterns were observed on the as-grown surfaces of CdS. The crystal structures of the CdS films deposited on the {111} “As-face” of GaAs were found to depend upon the deposition temperature. At higher temperatures (substrate temperatures \gtrsim840°C) epitaxial growth of the hexagonal phase occurs, while at lower temperatures \lesssim800°C) mixed cubic and hexagonal structures are found in early stages of growth, followed by the prevalence of the cubic phase as the growth proceeds. The origin of star-like growth hillocks observed on the CdS films on the {111} “As-face” of GaAs is discussed.