Highly transparent and resistive nanocrystalline ZnO-SnO2 films prepared by rf magnetron sputtering

ZnO-$SnO_2$ films were deposited by rf magnetron sputtering using a ZnO-$SnO_2$ (2:1 molar ratio) target. The target was made from a mixture of ZnO and $SnO_2$ powders calcined at $800^{\circ}C$. The working pressure was 1 mTorr, and the rf power was 120 W. The ratio of oxygen to argon ($O_2$:Ar) was varied from 0% to 10%, and the substrate temperature was varied from $27^{\circ}C$ to $300^{\circ}C$. The crystallographic properties and the surface morphologies of the films were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force spectroscopy (AFM). The ZnO-$SnO_2$ films deposited in $O_2$:Ar = 10% exhibited resistivity higher than $10^6{\Omega}cm$ and transmittance of more than 80% in the visible range.