Effects of Substrate Temperature on material characteristics of sputtered Aluminum doped ZnO thin films

Transparent conductive layers (TCOs) attract the attention in opto-electronic and photovoltaic device applications due to their conductivity and transparency characteristics in the visible region of the solar spectrum. There are various TCO thin film layers, and indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) are the most popular thin films such as the desired material characteristics of SnO2and ZnO, respectively. In literature, the works indicated that the characteristics of these films can be changed by using different deposition techniques. In this work, sputtering technique was used to fabricate the AZO film samples. AZO film samples were deposited on the ultrasonically cleaned commercial soda lime glass substrates at the substrate temperature of 300-573 K. The samples were fabricated by using DC/RF magnetron sputtering system. In general, the work was concentrated on the structural, electrical and optical properties of the AZO thin films with respect to the substrate temperature. In addition, post-annealing processes were applied to investigate the annealing effect on the material properties. The characterizations of thethin films were done by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) for structural analysis, UV/Vis transmission measurements for optical analysis and dark conductivity measurements for electrical analysis. In XRD spectra, all the deposited thin films were found highly oriented in the (002) orientation direction. By using transmission values, band gap energies of the films were investigated under the effect of substrate and annealing temperature. According to corresponding Tauc plots, the value of the band gap of AZO thin films increased with increasing deposition temperature. In addition, electrical measurements were done by four-point probe system and the electrical resistivity of the AZO films were quite sensitive to the substrate temperature and the value of resistivity values were found in decreasing behavior with increasing deposition temperature