INVESTIGATION OF THE OPTOELECTRONIC BEHAVIOUR OF ANNEALED AND UNANNEALED ELECTRODEPOSITED CADMIUM TELLURIDE THIN FILMS FOR MATERIAL DEVICE APPLICATIONS

Abstract

The investigation of the optoelectronic behaviour of annealed and un-annealed electrodeposited cadmium telluride (CdTe) thin films for material device applications was studied. Thin films of CdTe semiconductor materials were grown on fluorine doped tin oxide (FTO) conducting glass substrates using the technique of electrodeposition. Cadmium sulphate (CdSO4 +) at high concentrations and telluride oxide (TeO2+) at low concentrations were used as precursor salts for electrodeposition. Cathodic deposition potential of 1400 mV at duration of 30 to 120 minutes was used in this work. The electrical conductivity type and optical characteristics of annealed and un annealed CdTe thin films were carried out using photo-electrochemical (PEC) cell and UV-Vis spectrophotometry techniques respectively. The deposited samples converted from n-type to p type after heat treatment. The energy band gaps decreases as time increases for both un-annealed and annealed samples. The optical transmission for both annealed and un-annealed CdTe samples were about 60% for wavelengths longer than 850 nm. The results indicate that the material has potential application in the fabrication of CdTe solar cells.