Effect of deposition time and annealing process in chemical bath deposited CdS thin film

In this study, cadmium sulphide (CdS) thin layers are deposited at different deposition time periods (2.5, 3.5 and 5 h) on glass substrate by chemical bath deposition (CBD) technique at 60∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$60^{\circ }$$\end{document}C. The Seebeck effect, XRD and Raman spectra, SEM images and EDX analysis indicated the formation of n-type, amorphous nanograins, with relatively low sulphur deficiencies. The optical characterisations showed that the optical band gaps of the layers are varying in the range of 2.10–2.30 eV, as a result of band tail width originated from the sulphur vacancies acting as native donor-like levels distributed close to the conduction band edge, consistent with the EDX analysis. We also found that through the annealing treatments, the diameters of the nanograins are increased, the crystallinity of the layer has improved, and more importantly its electrical conductivity has largely increased (∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document} 8 times), which is very important in CdS-related heterostructure photovoltaic applications.