Transparent Conducting Amorphous IZO Thin Films: An Approach to Improve the Transparent Electrode Quality.

It is common knowledge that using different oxygen contents in the working gas during sputtering deposition results in fabrication of indium zinc oxide (IZO) films with a wide range of optoelectronic properties. It is also important that high deposition temperature is not required to achieve excellent transparent electrode quality in the IZO films. Modulation of the oxygen content in the working gas during RF sputtering of IZO ceramic targets was used to deposit IZO-based multilayers in which the ultrathin IZO unit layers with high electron mobility (µ-IZO) alternate with ones characterized by high concentration of free electrons (n-IZO). As a result of optimizing the thicknesses of each type of unit layer, low-temperature 400 nm thick IZO multilayers with excellent transparent electrode quality, indicated by the low sheet resistance (R ≤ 8 Ω/sq.) with high transmittance in the visible range (T¯ > 83%) and a very flat multilayer surface, were obtained.

On the Effect of the Co-Introduction of Al and Ga Impurities on the Electrical Performance of Transparent Conductive ZnO-Based Thin Films.

In this study, a set of ZnO-based thin films were prepared on glass substrates at various substrate temperatures via the direct current magnetron sputtering of ceramic targets with the following compositions: pure ZnO, Al-doped ZnO with doping levels of 1 and 2 at.%, Ga-doped ZnO with doping levels of 1 and 2 at.%, and (Al, Ga)-co-doped ZnO with doping levels of 1 and 2 at.% for each impurity metal. The dependencies of sheet resistance, carrier concentration, and Hall mobility on the substrate temperature were studied for the deposited films. The results of evaluating the electrical performances of the films were compared with the data of their XRD study. According to the XRD data, among all the deposited ZnO films, the maximum crystallinity was found in the co-doped thin film with doping levels of 2 at.% for each impurity metal, deposited at a substrate temperature of 300 °C. It was revealed that the observed increase in the Hall mobility and carrier concentration for the co-doped films may, in particular, be due to the difference in the preferred localization of Ga and Al impurities in the ZnO film: the Ga ions were mainly incorporated into the crystal lattice of ZnO nanocrystallites, while the Al impurity was mostly localized in the intercrystalline space at the grain boundaries.