p-type ZnO films prepared by alternate deposition of ZnO and Mg3N2 films Original Research Article

A p-type ZnO film was successfully obtained by the alternate deposition of ZnO and Mg3N2 in radio-frequency (RF) magnetron sputtering process. ZnO and Mg3N2 (or Mg-oxynitride) films were alternately deposited on a substrate rotated above ZnO and Mg3N2 targets, where ZnO and Mg3N2-sputtering were carried out at RF power of 30 W and 0–90 W, respectively. In the case of the alternate deposition, where the substrate was kept for 0.2 s above the Mg3N2 target, p-type ZnO films were grown by Mg3N2-sputtering at 50–70 W, whereas an n-type ZnO film was grown at 90 W. The c-axis lengths of the films prepared by Mg3N2-sputtering at 0–50 W increase with RF power, and oppositely the c-axis lengths of the films prepared by Mg3N2-sputtering at 60–90 W decrease with RF power. p-type ZnO films were grown by Mg3N2-sputtering at 50 W for 2 and 5 s, whereas insulative ZnO films were grown by Mg3N2-sputtering at 70 W for 2 and 5 s. The band-gap energies of the p-type ZnO films prepared by Mg3N2-sputtering at 50 W for 0.2 and 5 s are estimated to be 3.31 and 3.39 eV, respectively. The increase of the band-gap energies of the p-type ZnO films is caused by the intermixing of ZnO and Mg-oxynitride films.