P-type conductivity and stability of nitrogen-doped zinc oxide prepared by magnetron sputtering

Nitrogen (N)-doped zinc oxide (ZnO:N) films were deposited on quartz glass substrates at 510 K by reactive radio-frequency magnetron sputtering of a ZnO target with sputtering gas of nitrogen. The as-grown ZnO:N shows insulating at room temperature, but behaves p-type conduction with resistivity of 456 Ω cm, carrier concentration of 1.2×1017 cm−3 and Hall mobility of 0.1 cm2/V s in the dark after annealed at 860 K for 1 h under 10−4 Pa. Unfortunately, the p-type conduction is not stable in the dark and transforms into n-type gradually. After irradiated by sunlight for a few of minutes, the n-type ZnO:N reverts to metastable p-type one in the dark and remains p-type conductivity in the brightness. Formation and stability of the p-type ZnO:N are discussed in the present paper.