engleski

The role of thermal processing for achieving homogeneity of magnetron sputtered AZO films

Transparent conductive thin-films have received much attention due to their high conductivity and transmittance as well as broad areas of use (optoelectronic devices, e.g. solar cells). In comparison to the widely used indium tin oxide (ITO) films, aluminium doped zinc oxide (AZO) films represent a low cost alternative that can be easily deposited by a variety of chemical and physical methods [1, 2]. In order to determine the optimal conditions for obtaining films that can be used as transparent conductive oxide layers (TCO) we investigated the course of preparing AZO films by DC magnetron sputtering using two source targets: zincite (ZnO) and aluminium (Al). DC power was varied during the deposition on glass substrates and derived films were subsequently thermally treated. All films display hexagonal wurtzite structure of zincite regardless of the deposition parameters as shown by X-ray diffraction analysis (XRD). The average transmittance of the films was more than 85% in the visible range (400 to 800 nm). The Al content and thermal treatment were responsible for variations of the average grain size and achieved morphology, which was confirmed by electron and atomic force microscopies (SEM and AFM) as well as synchrotron radiation scattering experiments (SAXS). Finally, solid state dielectric spectroscopy measurements (SS IS) described the development of electrical conductivity with temperature in the prepared thin-films. It was found that the optimisations of the thermal processing play a key role in tailoring of layers with advanced charge transport functionalities. The investigation brings to conclusion that application of the subsequent thermal processing can improve both electrical and optical properties of the AZO films derived by magnetron sputtering.

thin films ; magnetron sputtering ; AZO ; SAXS

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