Growth ambient dependent electrical properties of lithium and nitrogen dual-doped ZnO films prepared by radio-frequency magnetron sputtering

Lithium (Li) and nitrogen (N) dual-doped ZnO films with wurtzite structure were prepared by radio-frequency magnetron sputtering ZnO target with Li3N in growth ambient of pure Ar and the mixture of Ar and O2, respectively, and then post annealing techniques. The film showed week p-type conductivity as the ambient was pure Ar, but stable p-type conductivity with a hole concentration of 3.46 × 1017 cm− 3, Hall mobility of 5.27 cm2/Vs and resistivity of 3.43 Ω cm when the ambient is the mixture of Ar and O2 with the molar ratio of 60:1. The stable p-type conductivity is due to substitution of Li for Zn (LiZn) and formation of complex of interstitial Li (Lii) and substitutional N at O site, the former forms a LiZn acceptor, and the latter depresses compensation of Lii donor for LiZn acceptor. The level of the LiZn acceptor is estimated to be 131.6 meV by using temperature-dependent photoluminescence spectrum measurement and Haynes rule. Mechanism about the effect of the ambient on the conductivity is discussed in the present work.