Growth and properties of Zn 1− xCd xS films on GaAs by low-pressure MOVPE

Abstract

Cubic Zn 1− x Cd x S ternary alloy epitaxial films have been grown on (100) GaAs by low-pressure metalorganic vapor phase epitaxy (MOVPE) using dimethyl zinc, dimethyl cadmium and hydrogen sulfide as reactants. The solid composition is shown to be easily controlled over the whole range of composition, although the films tend to be Cd-rich compared with the case of atmospheric pressure MOVPE. It has been found that the solid composition slightly decreases with growth temperature due to the effect of the decrease in the sticking coefficient of cadmium with temperature. The photoluminescence spectra at 18 K of the ternary films are dominated by fairly strong free-to-acceptor emissions. Furthermore, it is shown that low-resistivity ternary films can be grown by iodine doping.