Preparation of p-type ZnO thin films by RF diode sputtering

A p-type ZnO thin film was prepared by RF diode sputtering and nitrogen doping. Deposition in plasma N<sub>2</sub> gas source increases the N solubility and thus the incorporation of N<sub>o</sub> acceptor that is responsible for p-type conductivity of the ZnO films. Raman analyses performed in back scattering configuration proved the incorporation of the nitrogen acceptor N<sub>o</sub> into ZnO:N. Raman spectra show E<sub>2</sub> mode and two nitrogen related local vibrational modes (LVMs) typical for N-doped ZnO. Minimum resistivity of 790 Omegacm, a Hall mobility of 22 cm<sup>2</sup>V<sup>-1</sup>s<sup>-1</sup> and the carrier concentration of 3.6 times 10<sup>14</sup> cm<sup>-3</sup>were obtained at 75 %N<sub>2</sub> in Ar/N<sub>2</sub> sputtering gas. X-ray diffraction measurements (XRD) showed that ZnO:N films had the preferential orientation of (002) plane at 25 %N<sub>2</sub> and of (100) plane for higher N<sub>2</sub> concentrations. The average grain size was from 7 to 42 nm for all Ar/N<sub>2</sub> ratios. ZnO:N films exhibit relatively high microstrains (10 times 10<sub>-3</sub>)