Effects of oxygen partial pressure on the structural and optical properties of undoped and Cu-doped ZnO thin films prepared by magnetron co-sputtering

Abstract

Undoped and Cu-doped zinc oxide (ZnO:Cu) films were deposited on glass substrates by magnetron sputtering at different oxygen partial pressures po. Microstructure, surface morphology, resistivity, and optical properties were systematically investigated. The results show that lower po can degrade the crystallinity, and reduce the band gap. Undoped ZnO films are not obviously influenced by po, especially at high oxygen pressure. In contrast, ZnO:Cu thin films are remarkably affected by po. This work suggests that oxygen vacancies play an important role in modifying properties and allows us to accurately modulate the band gap of the ZnO-based films.