Optical and structural properties of CdS thin films grown by chemical bath deposition doped with Ag by ion exchange

Abstract

In this work thin CdS films using glycine as a complexing agent were fabricated by chemical bath deposition and then doped with silver (Ag), by an ion exchange process with different concentrations of AgNO3 solutions. The CdS films were immersed in silver solutions using different concentrations during 1min for doping and after that the films were annealed at 200°C during 20min for dopant diffusion after the immersion on the AgNO3 solutions. The aim of this research was to know the effects of different concentrations of Ag on the optical and structural properties of CdS thin films. The optical band gap of the doped films was determined by transmittance measurements, with the results of transmittance varying between 35% and 70% up to 450nm in the electromagnetic spectra and the band gap varying between 2.31 and 2.51eV depending of the silver content. X-ray photoelectron spectroscopy was used to study the influence of silver on the CdS:Ag films, as a function of the AgNO3 solution concentration. The crystal structure of the thin CdS:Ag films was studied by the X-ray diffraction method and the film surface morphology was studied by atomic force microscopy. Using the ion exchange process, the CdS films’ structural, optical and electric characteristics were modified according to silver nitrate concentration used.