Chemical Activity of Oxygen Atoms in Magnetron Sputter-Deposited ZnO Films during Film Growth

Abstract

The role of oxygen atoms in the growth of magnetron sputter-deposited ZnO films was studied by alternating the deposition of a several-nanometer-thick ZnO layer and an O2/Ar mixed plasma exposure, i.e., a layer-by-layer (LbL) technique. Film crystallization was promoted by suppressing the formation of oxygen vacancies and interstitial defects by adjusting the exposure conditions of the O2/Ar plasma. These findings suggest that the chemical potential of oxygen atoms influences film crystallization and the electronic state. The diffusion and effusion of oxygen atoms at the growing surface have effects similar to those of thermal annealing, namely, the promotion of film crystallization and the creation and annihilation of oxygen- and zinc-related defects. The role of oxygen atoms reaching the growing film surface is discussed in terms of chemical annealing, and a possible oxygen diffusion mechanism is proposed.