Sol–gel spin coating derived cadmium oxide semiconductor thin films: Effect of Lutetium contribution

Abstract

Continuously developing optoelectronic technology requires alternative transparent conductive oxide (TCO) materials. Due to their high optical transmittance and conductivity, TCO materials have many application areas. Cadmium oxide (CdO) thin films, one of the most important TCO materials, are frequently used in optoelectronic technology. In this study, pure and Lu doped CdO semiconductor thin films with 1, 2, 3, 4, and 5 at% concentrations were produced using the sol- gel spin coating technique. The changes in the optical, structural and surface properties of the films were examined as a function of the doping and it was determined that the doping process caused significant changes in the properties of the films. The XRD results showed that the samples were polycrystalline cubic and the average crystallite size varied between 13.42 nm and 26.39 nm with Lu contribution. To examine the optical properties of CdO: Lu thin films, the transmittance and absorption spectra of the films were taken in the UV–VIS region. The optical absorption coefficient, refractive indexes, dielectric constants, optical-electrical conductance, and optical band-gap of films were calculated by using the obtained transmittance and absorption spectra, and the effect of doping on the optical properties of the films was investigated. Depending on the amount of Lu, some fluctuations are observed in Eg values. It was determined that Lu doping from the changes in SEM is effective in changing the properties of CdO and these films are suitable materials for sensor and display applications. SEM images revealed that the Lu contribution rate caused the surface change of thin films. With this study, the effect of Lu doping on structural, optical, and superficial properties of CdO films was investigated and it was determined that Lu doping of CdO films were suitable materials for optoelectronic applications.