Optical and Morphological Studies of Electrodeposited CdS Thin Film Grown at Different Deposition Times from Acetate Precursor

Electrodeposited cadmium sulfide (ED-CdS) thin films were prepared on fluorine-doped tin oxide (FTO) substrate at six different deposition times in order to study the impact of deposition time on their properties for possible solar cell application. The deposition was carried out from an electrolytic bath containing cadmium acetate Cd(CH3COO)(2) and sodium thiosulfate (Na2S2O3) using simple two electrode configuration. The deposition time was varied at 30, 40, 50, 60, 70 and 80 minutes. The corresponding optical, morphological, surface roughness, compositional and structural properties of the deposited films were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM), scanning probe microscopy (SPM), energy dispersive X-ray spectroscopy (EDS) and glancing incidence X-ray diffraction (GIXRD) respectively. The results show that, the estimated energy band gaps were in the range of 2.35 to 2.20 eV as deposition time increases, for as-deposited films and 2.38 to 2.30 eV for annealed films. SEM images show very compact and agglomerated spherical grains. From SPM measurements it is observed that, the surface roughness ranges from 2.51 nm to 2.73 nm for as-deposited samples and 1.76 nm to 2.15 nm for annealed ones. EDS shows that the films are cadmium-rich in both as-deposited and annealed conditions. (C) 2019 The Electrochemical Society.