Issue 16, 2017

Orientation-dependent chemistry and band-bending of Ti on polar ZnO surfaces

Abstract

Orientation-dependent reactivity and band-bending are evidenced upon Ti deposition (1–10 Å) on polar ZnO(0001)–Zn and ZnO(000[1 with combining macron])–O surfaces. At the onset of the Ti deposition, a downward band-bending was observed on ZnO(000[1 with combining macron])–O while no change occurred on ZnO(0001)–Zn. Combining this with the photoemission analysis of the Ti 2p core level and Zn L3(L2)M45M45 Auger transition, it is established that the Ti/ZnO reaction is of the form Ti + 2ZnO → TiO2 + 2Zn on ZnO(0001)–Zn and Ti + yZnO → TiZnxOy + (yx)Zn on ZnO(000[1 with combining macron])–O. Consistently, upon annealing thicker Ti adlayers, the metallic zinc is removed to leave ZnO(0001)–Zn surfaces covered with a TiO2-like phase and ZnO(000[1 with combining macron])–O surfaces covered with a defined (Ti, Zn, O) compound. Finally, a difference in the activation temperature between the O-terminated (500 K) and Zn-terminated (700 K) surfaces is observed, which is tentatively explained by different electric fields in the space charge layer at ZnO surfaces.

Graphical abstract: Orientation-dependent chemistry and band-bending of Ti on polar ZnO surfaces

Supplementary files

Article information

Article type
Paper
Submitted
16 Dec 2016
Accepted
17 Mar 2017
First published
20 Mar 2017

Phys. Chem. Chem. Phys., 2017,19, 10350-10357

Orientation-dependent chemistry and band-bending of Ti on polar ZnO surfaces

P. Borghetti, Y. Mouchaal, Z. Dai, G. Cabailh, S. Chenot, R. Lazzari and J. Jupille, Phys. Chem. Chem. Phys., 2017, 19, 10350 DOI: 10.1039/C6CP08595D

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