Localization of aluminum in ZnO: Al layers during magnetron sputtering deposition

Abstract

The features of aluminum localization and the mechanism of donor center formation in ZnO:Al layers synthesized by high-frequency magnetron sputtering are studied. It is shown that aluminum predominantly localizes at grain boundaries of zinc oxide in its own oxide phase. The mechanism of aluminum oxidation at grain boundaries significantly depends on the oxygen content in the working chamber: during sputtering in an atmosphere of pure argon under conditions of oxygen deficiency, aluminum oxidation occurs as a result of interaction with oxygen from the surface layer of zinc oxide crystallites, forming surface donor centers at grain boundaries. With an increase in the partial pressure of oxygen, aluminum is predominantly oxidized by oxygen from the gas atmosphere, forming its own barrier phase at grain boundaries.