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 N₂ gas source increases the N solubility and thus the incorporation of N_o 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_o into ZnO:N. Raman spectra show E₂ mode and two nitrogen related local vibrational modes (LVMs) typical for N-doped ZnO. Minimum resistivity of 790 Omegacm, a Hall mobility of 22 cm²V^-1s^-1 and the carrier concentration of 3.6 times 10¹⁴ cm^-3were obtained at 75 %N₂ in Ar/N₂ sputtering gas. X-ray diffraction measurements (XRD) showed that ZnO:N films had the preferential orientation of (002) plane at 25 %N₂ and of (100) plane for higher N₂ concentrations. The average grain size was from 7 to 42 nm for all Ar/N₂ ratios. ZnO:N films exhibit relatively high microstrains (10 times 10_-3)