Effect of growth temperature on the electronic energy band and crystal structure of ZnS thin films grown using atomic layer epitaxy

Abstract

Electroreflectance (ER) technique has been used to study the effect of growth temperature and source materials on the electronic energy band and crystal structure of zinc sulfide thin films grown using atomic layer epitaxy (ALE). The samples studied were grown by ALE at 300–500 °C from zinc acetate or zinc chloride and hydrogen sulfide. The ER spectra were measured at room temperature and at 77 K. The crystal structure of polycrystalline ZnS thin films grown from zinc acetate at 300–375 °C is mainly cubic, whereas the ZnS layers grown from zinc chloride at 425–500 °C are predominantly hexagonal. The ER spectra of the latter samples show peaks belonging to the cubic structure, too. The crystal structure of zinc sulfide thin films is found to depend both on growth temperature and on source materials.