The effects of thermal annealing in NH3 -ambient on the p-type ZnO films

Thermal annealing in NH3-ambient was carried out to form p-type ZnO films. The properties were examined by X-ray diffraction (XRD), Hall-effect measurement, photoluminescence (PL), and secondary ion mass spectrometry (SIMS). Electron concentrations in ZnO films were in the range of 1015–1017/cm3 with thermal annealing in NH3-ambient. The activation thermal annealing process was needed at 800 ∘C under N2-ambient to obtain p-type ZnO. The electrical properties of the p-type ZnO showed a hole concentration of 1.06×1016/cm3, a mobility of 15.8 cm2/V s, and a resistivity of 40.18 Ω cm. The N-doped ZnO films showed a strong photoluminescence peak at 3.306 eV at 13 K, which is closely related to neutral acceptor bound excitons of the p-type ZnO. The incorporation of nitrogen was confirmed in the SIMS spectra.