Institute of Computational and Theoretical Studies
Using low temperature scanning tunneling microscopy (STM), we discovered locally ordered patches of O adatoms and single Zn vacancies on the Zn-terminated ZnO(0001) polar surface. Such patches are determined to be metastable ordered structures on the surface. Density functional theory (DFT) calculations show that Zn atoms bonded to an O adatom encounter a larger reaction barrier for leaving lattice sites, explaining the observed general disordered nature of the Zn-terminated surface that is populated by cavities of different shapes and sizes and disordered distribution of adatoms. The interplay among different driving mechanisms provides valuable insight as to how a polar surface of an ionic crystal achieves its lowest energy reconstructed surface structure. Comparisons between the charge on surface vs bulk layers for a relaxed (1 × 1) slab and a slab bounded on two ends by reconstructed surfaces with stoichiometric changes reveal that in a neutral environment, the polar surface of an ionic crystal tends to go through reconstructions that allow cations to donate electrons to anions in amounts very similar to that in the bulk.
Source Publication Title
Journal of Physical Chemistry C
American Chemical Society
© 2016 American Chemical Society. Observation and Analysis of Ordered and Disordered Structures on the ZnO(0001) Polar Surface Hu Xu, Lei Dong, Xingqiang Shi, Yang Liu, Michel A. Van Hove, Nian Lin, and S. Y. Tong The Journal of Physical Chemistry C 2016 120 (47), 26915-26921 DOI: 10.1021/acs.jpcc.6b09217
The work was supported in part by NSFC (Grant Nos. 11334003, 11674148, 11204185, and 11104272), by the Basic Research Program of Science, Technology and Innovation Commission of Shenzhen Municipality (Grant No. JCYJ20160531190054083), by the Hong Kong Research Grant Council CRF Grant CityU6/CRF/08, and by the Hong Kong Baptist University Strategic Development Fund. We also thank the High Performance Cluster Computing Centre, Hong Kong Baptist University, which receives funding from the Research Grants Council, University Grants Committee of the HKSAR, and Hong Kong Baptist University.
Link to Publisher's Edition
Xu, Hu, Lei Dong, Xingqiang Shi, Yang Liu, Michel A. Van Hove, Nian Lin, and S. Y. Tong. "Observation and analysis of ordered and disordered structures on the ZnO(0001) polar surface." Journal of Physical Chemistry C 120.47 (2016): 26915-26921.