C-axis oriented ZnO films are deposited on polished diamond substrates in various O2/(O2+Ar) ratios using the radio frequency (RF) magnetron sputtering technique and are subsequently annealed in oxygen ambience under the same conditions. Structural, morphologic and electrical properties of ZnO films are characterized by X-ray diffraction (XRD), high-resistance instrument, energy dispersive X-ray spectroscopy (EDS) and scanning electronic microscopy (SEM). As the O2/(O2+Ar) ratio increasing from 1/12 to 5/12, the crystallinity of the as grown ZnO films becomes better and the electrical resistivity increases slowly. After annealing, the ZnO films deposited in O2/(O2+Ar) =1/12 and 3/12 are improved greatly in crystallinity, and their electrical resistivity is enhanced by two orders of magnitude, while those deposited in O2/(O2+Ar) =5/12 are scarcely changed in crystallinity, and their resistivity is only increased by one order. In addition, the ZnO films deposited in O2/(O2+Ar) =3/12 and annealed in oxygen are with the best crystal quality and the highest resistivity.
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