Untitled

Abstract

In this work multilayer films of CdS/ZnS and CdS/CoS were prepared using the chemical bath deposition technique. The influence of substrate materials on structural, morphological, compositional and optical properties of the films was investigated. The powder X-ray diffraction (XRD) pattern of CdS/ZnS thin film showed nearly similar structure to that of the cubic ZnS structure. The XRD pattern of CdS/CoS thin films confirmed the co-existence of hexagonal and orthorhombic CdS phases. A cubic CdS structure is observed for CdS/glass thin film. The scanning electron microscopy (SEM) micrograph of CdS/glass film revealed spherical grains of size 125 nm covering the substrate uniformly without voids and cracks. The as large grain size as 800 nm with distinct grain boundaries was observed for CdS/ZnS multilayer film with some voids on the surface. The SEM micrograph of CdS/CoS thin film showed spherical surface grains of size 450 nm on flat and compact background. The energy dispersive X-ray spectra of single and multilayer CdS films confirmed the presence of Cd and S. The optical analysis of the CdS/glass, CdS/ZnS and CdS/CoS thin films confirmed band gaps of 2.5, 2.3 and 2.27 eV respectively.