Zinc oxide targets for magnetron sputtering PVD prepared by plasma spray

TCO (Transparent Conductive Oxides) is a class of thin coatings which industrial importance is dramatically increasing. Their applications span from solar cells up to touch screen devices. Among them, ZnO has interesting electromagnetic properties, jointly to a price of raw materials significantly lower with respect to the Indium oxide based coatings, which are the most commonly used.TCO are usually produced by magnetron sputtering PVD, starting from a ceramic target, and plasma spraying technology is in some cases used to prepare targets. In the present work the preparation of ZnO targets by means of plasma spray is investigated, focussing on the effect of plasma spray process on the electromagnetic properties of the final thin film deposited using the obtained targets.As a first step, the effect of deposition parameters on the micro structural properties of the ZnO plasma sprayed coatings has been assessed. Coatings were characterised by means of SEM, EDS, and XRD. It was observed that coatings deposited under inert atmosphere contained a small amount of metallic Zn.Two targets for a magnetron sputtering PVD equipment were prepared depositing by plasma spraying ZnO layers onto metallic substrates. The two targets differed for the deposition atmosphere: air for the first target, Ar for the second one. Thin PVD coatings, deposited starting from the above mentioned targets, were analysed by means of SEM, XRD, XPS, and Hall effect, in order to correlate their characteristics with the target preparation process parameters.PVD coatings obtained by the target prepared in air presented a high value of resistivity. Coatings deposited using the target prepared under inert atmosphere had a high value of electrical conductivity. No metallic Zn was detected in the PVD coatings.