Process parameter dependent property studies on CdO films prepared by DC reactive magnetron sputtering

Cadmium oxide (CdO) films were deposited by DC reactive magnetron sputtering on glass substrates at different oxygen partial pressures and substrate temperatures. Dependence of the physical properties of CdO films on the process parameters was systematically investigated. The stoichiometry of the films was found to be improved with increase in the oxygen partial pressure and the substrate temperature. The films were polycrystalline in nature with cubic structure and found to be predominantly (1 1 1) oriented when prepared at substrate temperatures ≤523 K, whereas those deposited at temperatures ≥623 K were (2 0 0) oriented. The temperature dependence of Hall mobility revealed the grain boundary scattering of the charge carriers was the prominent electrical conduction mechanism in these films. The optical transmittance and the band gap of the films were found to be increased with increase in the oxygen partial pressure and the substrate temperature. The CdO films prepared under optimized oxygen partial pressure of 1×10−3 mbar and substrate temperature of 623 K have a resistivity of 8.2×10−4 Ohm cm and visible transmittance of 85% with a figure of merit value of 7.5×103 Ohm−1 cm−1.