Determination of ZnO(0001) surface termination by x-ray photoelectron spectroscopy at photoemission angles of 0° and 70

• Published in: Surface and interface analysis Vol. 36; no. 11; pp. 1479 - 1483
• Main Authors: Zhang, L., Wett, D., Szargan, R., Chassé, T.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.11.2004; Wiley
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Physics; surface termination; x-ray photoelectron spectroscopy; ZnO; Inorganic compounds; Epitaxial layers; Surface contamination; In situ; Transition element compounds; Core levels; Thickness measurement; Thickness; Surface termination; Zinc oxides; Monocrystals; Photoemission; x-ray photoelectron spectroscopy; ZnO; Aluminium oxides; X-ray photoelectron spectra
• ISSN: 0142-2421; 1096-9918
• DOI: 10.1002/sia.1924

We present an XPS method to determine the termination of the ZnO(0001) surface. By measuring O 1s and Zn 2p3/2 core‐level x‐ray photoelectron spectra at photoemission angles of 0° and 70° and comparing the intensity ratio (IO1s/IZn2p3)θ=0/(IO1s/IZn2p3)θ=70, the Zn and O termination can be distinguished. Calculations show that these two terminations have intensity ratios differing by ∼17%. This difference is not affected by a contamination layer provided that the contamination layer thickness is the same for these two differently terminated surfaces. Although this determination method prefers a clean ZnO(0001) surface (in situ measurement), it seems also feasible for surfaces with known contamination layer thickness (ex situ measurement). We have measured ex situ ZnO(0001)‐Zn, ZnO(000&1macr;)‐O single crystals and an epitaxial ZnO film deposited on Al2O3(0001). The measured intensity ratios of the first two samples agree with the calculated values for a 0.2 and 0.26 nm contamination layer, respectively. The intensity ratio and the O 1s contamination component intensity of the epitaxial ZnO film are close to those of the ZnO(0001)‐Zn single crystal thus pointing at Zn termination of the film. Copyright © 2004 John Wiley & Sons, Ltd.