Effect of Cd/S molar ratio on the optical and electrical properties of spray deposited CdS thin films

Cadmium sulphide thin films were deposited from the solutions containing precursor materials with different Cd/S molar ratios on glass substrates by spray pyrolysis. The grown CdS thin film show hexagonal structures as indicated by powder XRD studies. Surface morphology and elemental composition in the films were obtained from FESEM and EDX measurements, respectively. The optical properties of CdS films were less influenced by Cd/S molar ratio in the solution where as resistivity is found to be sensitive to precursor molar ratio. Transmittance of the films was found to be above 80%. The lowest resistivity of 1.04x10(2) Omega-cm were obtained for the films deposited from solution with Cd/S molar ratio equal to 0.5. The properties of the CdS thin films grown with Cd/S molar ratio equal to 0.5 appears suitable for window layer in heterojunction thin film solar cells.