Transparent conducting Zn_xCd_1-xO thin films prepared by the sol-gel process

Thin films of zinc oxide, cadmium oxide, and their compounds have been deposited by the sol-gel process. The ZnO and CdO films are found to have different crystallographic structures and their compounds are found to be simple mixtures of the two different crystallographic strutures for the constituent materials. The electrical resistivity of the compounds, Zn_xCd_1-xO thin films decreases as the composition x decreases, so that pure CdO thin films have the lowest electrical resistivity of 3 × 10^-3 Ωcm. Although the optical transmittance and bandgap of the Zn_xCd_1-xO films also decrease as the value of x decreases, all the films prepared in this study have a fairly high transmittance reproducibly in the visible spectral range at room temperature. The electrical resistivity of the films is found to have significant dependence on the post-deposition annealing environments. This dependence is more pronounced for the films which contain higher percentages of Zn among all the Zn_xCd_1-xO films prepared in this study. The dependence of the electrical resistivity on the aluminium impurity concentration in the Zn_xCd_1-xO films is also examined.