Properties of cadmium sulphide thin films deposited from a chemical solution

Cadmium sulphide thin films have been deposited chemically at different temperatures from 50 degrees C to 100 degrees C. The composition of the solution was [CdCl2] = 0.01 M, [Thiourea] = 0.17 M, [NH4Cl] =0.036 M and [NH3] = 0.36 M. Structural, electrical and optical properties were investigated as a function of deposition parameters. The films showed strongly oriented structures and were highly transmitting in the infrared region. Their absorption coefficient was in the range 10(4) to 10(5) cm(-1) in the visible region. The direct forbidden band had an energy gap of 2.48 eV and the refractive index for high wavelengths was equal to 2.116. The dark resistivities of as-deposited films thicker than 0.5 mu m had values from 10(3) to 10(5) Omega cm. These resistivities decreased to about 10 Omega cm after annealing in vaccum or in argon atmosphere at 200 degrees C for one hour.