Structural and electrical point of view on addressing the organisation of the constituting domains in DC magnetron sputtered AZO films

For the transparent conductive films, the upgrading of their inherent properties has received much attention in their extensive areas of use, such as for opto-electronic devices. In comparison to the widely used indium tin oxide (ITO), aluminium-doped zinc oxide (AZO) films represent a low-cost alternative that can be easily fabricated by a variety of chemical and physical methods of deposition. In order to find the optimal conditions for obtaining AZO films that can be used as transparent conductive oxide layers (TCO), we investigated AZO films prepared by magnetron sputtering (MS) on glass substrates by using two targets: ZnO and Al. We individually varied power at targets during the deposition and subsequently thermally treated the prepared films. All films showed either a hexagonal wurtzite zincite structure or no diffraction pattern without clear relation to deposition parameters. Morphologic parameters were observed by scanning electron and atomic force microscopies and scattering experiments. Primarily Al loading and the extent of the thermal treatment were held responsible for influencing the course of the development of the structure, morphology and electrical functionality. From the functional point of view, we focussed on frequency-dependent electrical measurements (solid-state impedance spectroscopy) to show and describe electrical conductivity behaviour. In conclusion, it was evident that there are several strategies available for the tailoring of the electrical and optical properties of the MS-derived AZO films, one of which is thermal post-processing. Graphical abstract