Deposition of Cd-Doped ZnO Thin Films as Transparent Electrode for Solar Cell Applications

Undoped and Cd-doped ZnO (CZO) thin films have been deposited by the magnetic spin coating method which is used for the first time in the literature, and the transparent electrode properties of thin films have been investigated. The microstructural properties of CZO thin films have also been investigated using X-ray diffraction (XRD). In the undoped and 1% Cd-doped ZnO films, the XRD diffraction pattern of the pure hexagonal ZnO was formed. In the films, with 3% Cd dopant, (010) peak of hexagonal CdZn structure in a very small intensity in the XRD pattern has started to be observed. In the films, with 5% Cd dopant, the (010) and (011) peaks of the same structure have been formed, respectively. The morphological properties and elemental composition of CZO thin films have been investigated using field emission scanning electron microscopy-energy dispersive x-ray spectroscopy (FESEM-EDX). FESEM images indicated that the films have been deposited homogeneously. In the undoped ZnO film, a hexagonal ZnO structure has been seen. With the increase of the dopant ratio, it has appeared that the Cd grains have increased on the surface. The optical properties of CZO thin films have been investigated using ultraviolet–visible (UV-Vis.) spectroscopy. An increase in the optical transmittance spectra has been observed with increasing Cd dopant ratio. The absorption edge changed and the optical energy bandgap value decreased with Cd doping.