Study of Selected Morphologic, Structural and Optical Effects of Silver Coated CBD-CdS Thin Films

This work focused on comparing cadmium sulphide (CdS) thin films with and without CdS silver aggregates (CdS:Ag) deposited on the surface. We report absorption and transmission responses. Using the Tauc method, we obtained direct band gap energies with values of 2.50 (CdS) and 2.49 eV (CdS:Ag). We performed a scanning electron microscope characterization at different magnifications were cluster formations with granular shapes were observed. The highest magnification of 50,000× showed silver clusters as shiny granulates, which were confirmed by microprobe elemental mapping at a magnification of 18,000×. Energy Dispersive Spectroscopy revealed that the light composition of the silver clusters was the unique difference from the CdS thin film. X-Ray Diffraction results only detected the hexagonal CdS pattern, but not that of silver. The crystallite size was of around 13 nm. A Surface-Enhanced Ramman Scattering effect was observed upon the silver coating of the CdS thin film at 293.3 cm-1.