Effect of growth voltage on electrodeposited CdS thin films using UV visible Spectrophotometer

Abstract

In Electrodeposition, six (6) parameters are necessarily considered during the deposition of the material layers. These are: pH, concentration of ions, time, deposition voltage, stirring and temperature. Four glass/FTO substrates were used to grow the CdS layers using 2-electrode electrodeposition (ED) method at different growth voltage, V_g (i.e 1400, 1300, 1200 & 1100) mV. The resulting films were then examined for optical characterization using UniCamp Spectrophotometer. The optical absorption measurement shows the value of bandgap, E_g for the film deposited at V_g 1300 mV has a bandgap of 2.43 eV which is close to the bulk material. The values of refractive index, extinction coefficient and absorption coefficient were generally lower at this particular V_g. The highest transmittance of >60% was observed for the layer grown at 1300 mV from optical transmittance spectra. The results suggest that the crystallinity of thin films decreases when the films are deposited at higher and lower voltages.