Effect of Deposition Time on the Optical Properties of Cadmium Sulphide Thin Films

In this study, we report on the effect of deposition time on the optical properties of SILAR (successive ionic layer and reaction) grown cadmium sulphide thin films. The films were characterised using a UV spectrophotometer to investigate the absorbance, transmittance, and reflectance versus wavelength measurements, to enable the determination of some important optical constants. The results show that deposition time had a strong influence on the properties of the films. The optical constants such as the energy bandgap, refractive index, extinction coefficient and the dielectric constants were found to vary with the deposition time. In particular, the energy bandgap was found to increase with an increase in the deposition time. The refractive index was in the range 1.2 to 1.8 while the extinction coefficient varied between 0.010 to 0.038. The values of the refractive index and extinction coefficient were slightly higher at the lower deposition time

On the structural and optical properties of SnS films grown by thermal evaporation method

Tin sulphide (SnS) has a direct energy band gap of 1.35 eV and it consists of abundant, non-toxic elements. It is therefore of interest for use as an absorber layer material in thin film photovoltaic solar cells. In this work, SnS layers with thicknesses in the range 2-3.6μm, were thermally evaporated onto glass substrates using substrate temperatures in the range 280°C to 360°C, and the way the structural and optical properties of the layers varied with the deposition conditions investigated. X-ray diffraction spectra showed a strong (040) reflection as the most prominent peak for films formed between 320°C to 360°C. The peak intensity ratio, crystallite size and grain size were observed to increase with increasing substrate temperature whilst the strain decreased. All the layers were highly light absorbing with the optical absorption coefficient, α > 104 cm−1. The optical energy band gap was found to be in the range, 1.30-1.34eV, it not changing substantially with substrate temperature. Other optical parameters such as the refractive index and optical conductivity were also evaluated for the layers grown at different substrate temperature