Wide range tuning of electrical conductivity of RF sputtered CdO thin films through oxygen partial pressure variation

The effect of oxygen partial pressure variation on the electrical conductivity and the optical transparency of CdO thin films, deposited through RF magnetron sputtering were studied in detail. Thin films of CdO have been deposited through radio frequency magnetron sputtering of a prefabricated CdO target at a fixed pressure 0.1 mbar and at a substrate temperature 523 K. It was found that the electrical conductivity of the CdO films could be varied over three decades for a variation of oxygen partial pressure of 0–100%, without introducing any extrinsic dopants. X-ray diffraction (XRD) studies showed that the films were polycrystalline in nature with a preferential orientation along (1 1 1) plane. Compositional information was obtained by X-ray photoelectron spectroscopic studies. This wide range of variation of electrical properties was explained through the oxygen vacancies formation.