Molecular beam epitaxial growth of ZnS on a (100)-oriented Si substrate

Abstract

ZnS films grown on (100) Si substrates were successfully obtained by molecular beam epitaxy. The dependence of the crystal quality on growth conditions was studied. The substrate temperature ( T s) and the molecular beam flux ration of Zn to S ( J Zn/ J S affect the crystal quality and the growth rate of the ZnS films profoundly. Crystallographic quality and surface morphology were significantly improved by growing at temperatures higher than 300°C. Below 300°C, growth orientation and growing planes of ZnS are different from others, namely ZnS(111) ‖ Si(511). The films grown at higher T s ( > 300°C) have the relation of ZnS(100) ‖ Si(100). By increasing J Zn/ J S, the surface morphology became worse. It is found that the optimum growth conditions are T s = 340° Cand J Zn/ J S =1 or 2. The growth rate of ZnS decreases with incresing T s , and increases with increasing J Zn/ J S and t hen saturates above J Zn/ J S = 3. From these results, it is presumable that ZnS growth is controlled by the sticking coefficient of the minority molecular species.