Preparation and Characterization of Transparent Conductive Nb-Doped ZnO Films by Radio-Frequency Sputtering

Niobium-doped ZnO (NZO) transparent conductive films are deposited on glass substrates by rf sputtering at 300°C. Effects of sputtering power on the structural, morphologic, electrical, and optical properties of NZO films are investigated by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Hall measurement, and optical transmission spectroscopy. The obtained films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The minimum resistivity of 4.0×10^-4Ω・cm is obtained from the film grown at the sputtering power of 170W. The average optical transmittance of the films is over 90%.