Temperature dependent structural, luminescent and XPS studies of CdO:Ga thin films deposited by spray pyrolysis

The structural, compositional, photoluminescent and XPS properties of CdO:Ga thin films deposited at temperatures ranging from 275 to 350 °C, using spray pyrolysis are reported. X-ray diffraction characterization of as-deposited GCO thin films reveals that films are of cubic structure with a (2 0 0) preferred orientation. The crystalline quality of the GCO films improves and the grain size increases with deposition temperature. The EDS analyses confirm oxygen deficiency present in the film and are responsible for n-type conductivity. The photoluminescence spectra demonstrated that the green emission peaks of CdO thin films are centered at 482 nm. The relative intensity of these peaks is strongly dependent on the deposition temperature. Oxygen vacancies are dominant luminescent centers for green emission in CdO thin films. The XPS measurement shows the presence of Cd, Ga, O and C elements and confirms that CdO:Ga films are cadmium-rich.

Research highlights▶ The CdO:Ga thin films seems an alternative to traditional TCO materials used in photovoltaic applications. This work deals the effect of deposition temperature on sprayed CdO:Ga films with respect to the structural, luminescent and XPS studies. ▶ The crystalline quality of the GCO films improves with deposition temperature. ▶ The oxygen vacancies are responsible for n-type conductivity and green emission. ▶ The minimum resistivity, highest carrier concentration and mobility are 1.9 × 10−4 Ω cm, 11.7 × 1021 cm−3 and 27.64 cm2 V−1 s−1, respectively.