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

ZnO-SnO2 films were deposited by rf magnetron sputtering using a ZnO-SnO2 (2:1 molar ratio) target. The target was made from a mixture of ZnO and SnO2 powders calcined at 800 degrees 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 degrees C to 300 degrees 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-SnO2 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.