Hydrogen-assisted nitrogen-acceptor doping in ZnO



N-doped ZnO (ZnO:N) thin films were prepared by atmospheric pressure mist chemical vapor deposition. The as-grown ZnO:N film was of high resistivity with ambiguous carrier type, while the annealed sample showed p-type conductivity with a resistivity of 22.3 Ω cm and hole concentration of 5.49 × 1017 cm–3. The crystallinity of ZnO films was improved by the annealing treatment. Unintentionally H impurities introduced into the as-grown film could be annealed out and a near-edge absorption related to the N states in band gap was present in the annealed sample, which was indicative of the appearance of activated N in ZnO during the annealing process. A hydrogen-assisted nitrogen-acceptor doping mechanism was proposed to explain the observation of p-type ZnO. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)