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Morphological Features and Band Bending at Nonpolar Surfaces of ZnO

DOI: 10.1021/acs.jpcc.5b01331 DOI Help

Authors: David Mora-fonz (University College London) , John Buckeridge (University College London) , Andrew J. Logsdail (University College London) , David O. Scanlon (University College London; Diamond Light Source) , Alexey A. Sokol (University College London) , Scott Woodley (University College London) , C. Richard A. Catlow (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C , VOL 119 , PAGES 11598 - 11611

State: Published (Approved)
Published: May 2015

Open Access Open Access

Abstract: We employ hybrid density functional calculations to analyze the structure and stability of the (101̅0) and (112̅0) ZnO surfaces, confirming the relative stability of the two surfaces. We then examine morphological features, including steps, dimer vacancies, and grooves, at the main nonpolar ZnO surface using density functional methods. Calculations explain why steps are common on the (101̅0) surface even at room temperature, as seen in experiment. The surface structure established has been used to obtain the definitive ionization potential and electron affinity of ZnO in good agreement with experiment. The band bending across the surface is analyzed by the decomposition of the density of states for each atomic layer. The upward surface band bending at the (101̅0) surface affects mostly the valence band by 0.32 eV, which results in the surface band gap closing by 0.31 eV; at the (112̅0) surface, the valence band remains flat and the conduction band bends up by 0.18 eV opening the surface band gap by 0.12 eV.

Subject Areas: Chemistry

Technical Areas: Theoretical Physics