Cadmium Oxide Thin Films Deposited by a Simplified Spray Pyrolysis Technique for Optoelectronic Applications

Cadmium oxide thin films were fabricated on glass substrates by a simplified and low cost spray pyrolysis technique at different substrate temperatures. The X-ray diffraction study showed that irrespective of substrate temperature all the films exhibits a preferential orientation along the (1 1 1) plane. The values of crystallite size were found to be in the range 20.72 – 29.6 nm. The percentage transmittance and the optical band gap values are found to be in the range of 78 – 89 % and 2.38 – 2.55 eV respectively. The optical transmittance is found to increase gradually with increase in substrate temperature. Urbach energy decreases with increase in substrate temperature. Optical parameters such as refractive index and packing density were calculated. The dispersion parameters of the as-deposited CdO films were calculated to analyze their choice in designing optical devices. PL studies confirm that the films exhibit strong luminescent properties. The value of ρ decreases with increase in substrate temperature and attains a minimum value of 0.26 x 10-6 ohm-m for the film coated at 375ºC which has the least thickness.