Electrical Conduction and Mechanism of Zinc Oxide Thin Films with Different Types and Levels of Defects

Abstract

ABSTRACTIn this work, the electrical conducting and mechanism of zinc oxide thin films with different types and levels of defects were investigated. The films were deposited by radio frequency magnetron sputtering sintered zinc oxide ceramic target under an atmosphere at different partial pressure ratios of O2 to Ar gases (O2/Ar ratio). Under the designed deposition conditions, all the prepared films were of wurtzite structure with a preferential growth orientation of c axis. With increasing O2/Ar ratio, the film thickness, deposition rate and grain size decreased, and the content of Zn in the films initially decreased and then increased. When the O2/Ar ratio was lower than 0.5, the dominant defects in the films were oxygen vacancies; when it was higher than 0.5, the main defects were interstitial zinc; but with an appropriate O2/Ar ratio of 0.5, the film composition may approach to the stoichiometric ZnO, which had the least number of defects. Resultantly, with increasing O2/Ar ratio, the electrical resistivity of the films initially increased and then decreased.