Sol - Gel Spin Coated Cadmium Sulphide Thin Films on Silicon (1 O 0) Substrates for Optoelectronic Applications

Cadmium chalcogenides with appropriate band gap energy have been attracting a great deal of attention because of their potential applications in optoelectronic devices. In this work CdS thin films were deposited on p type silicon substrates by sol gel spin coating method at different substrate temperatures. The CdS deposited wafers were characterized by X ray diffraction method (XRD), Scanning Electron Microscopy (SEM), Photoluminescence spectroscopy (PL), Raman spectroscopy and Fourier Transform Infra Red spectroscopy (FTIR). XRD analysis showed that the films have crystallites with classical hexagonal structure along (0 0 2) plane. The grain size was found to be in the range of 111.79 nm to 167.66 nm varying with the annealing temperature. The SEM micrograph of annealed CdS thin film showed uniform granular structures with very well defined grain boundaries all over the surface. The Raman spectra of the CdS films presented a well-resolved line at 300 cm (1LO) and at 611 cm-1 (2LO). PL spectrum showed a broad peak centered around 2.19 eV (508.5 nm) which can be attributed to the defect/trap related transitions. FTIR analysis showed absorption bands corresponding to Cd and S. The electrical property revealed that the resistivity decreases when the samples were annealed.