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

Abstract

Lithium (Li) and nitrogen (N) dual-doped ZnO films with wurtzite structure were prepared by radio-frequency magnetron sputtering ZnO target with Li 3N in growth ambient of pure Ar and the mixture of Ar and O 2, 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 × 10 17 cm − 3 , Hall mobility of 5.27 cm 2/Vs and resistivity of 3.43 Ω cm when the ambient is the mixture of Ar and O 2 with the molar ratio of 60:1. The stable p-type conductivity is due to substitution of Li for Zn (Li Zn) and formation of complex of interstitial Li (Li i) and substitutional N at O site, the former forms a Li Zn acceptor, and the latter depresses compensation of Li i donor for Li Zn acceptor. The level of the Li Zn 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.