Improved microstructure and properties of CBD-ZnS thin films

Abstract

ZnS thin films were prepared by chemical bath deposition method in alkaline liquor at different temperatures. Effects of deposition temperature on microstructure, surface morphology, composition, optical and electrical properties of ZnS thin films were systematically investigated. After optimized deposited condition, all the properties were improved. The results showed that all films were almost amorphous or microcrystalline and became more uniform and compact with increasing deposition temperature. The composition analysis revealed that film deposited at 85 °C had a good ratio of Zn/S. All of films had high transmittance with an average of 75 % in the range of 350–1,000 nm. The band gaps of all samples were in range of 3.47–3.78 eV. The film deposited at 85 °C had a high transmittance of about 80 % in the visible light region and the band gap was approximate to the standard value. The ZnS thin film is of n-type conductivity and the resistivity is found to be in the order of 10³ Ωcm. It can be found that seebeck coefficient increases from −217 to −263 μV/k with increasing temperature.