Influence of ZnO buffer layer deposition parameters on the structure and properties of Gadoped ZnO thin films

A series of transparent conductive films of gallium-doped zinc oxide (GZO) were deposited on glass substrates with various zinc oxide (ZnO) buffer layers by radio frequency (rf) magnetron sputtering. To investigate the influence of the ZnO buffer layer deposition parameters on the structure and properties of GZO films, the various ZnO buffer layers were prepared with varying annealing temperatures, sputtering pressures, thicknesses, and different rf powers. The crystallinity and grain sizes of the GZO films were investigated by the x-ray diffraction (XRD). Only the (002) diffraction peak located at 2∼34·2° appears in XRD spectrums indicating a hexagonal wurtzite structure with its strongly preferred orientation along the c-axis. It was found that the GZO film quality (low resistivity and high transmittance) could be improved by varying the ZnO buffer layer deposition parameters. The resistivity of the GZO films decreases from 5·01×1^0–3 to 9·45×10^–4 Ωcm and the visible range transmittance increases from 81·12 to 84·42%, when the GZO films were deposited on a 50 nm ZnO buffer layer annealed at 400 °C.