X-ray photoelectron spectroscopy and auger electron spectroscopy studies of Al-doped ZnO films

The chemical state of oxygen, aluminum and zinc in Al-doped ZnO (ZAO) films was investigated by X-ray photoelectron spectroscopy (XPS), as well as the transition zone of the film-to-substrate, by auger electron spectroscopy (AES). The results show that zinc remains mostly in the formal valence states of Zn2+. A distinct asymmetry in Al 2p(3/2) photoelectron peaks has been resolved into two components, one is metallic Al and the other is oxidized Al. The depth profile of the two components revealed that metallic Al mainly exists in the thin surface layer. The close inspection of Ols shows that Ols is composed of three components, centered at 530.15 +/- 0.15, 531.25 +/- 0.20 and 532.40 +/- 0.15 eV, respectively. AES reveals an abrupt transition zone between the ZAO and quartz substrate. (C) 2000 Elsevier Science B.V. All rights reserved.