Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 24: Semiconductor Substrates: Adsorption
O 24.3: Vortrag
Montag, 20. März 2017, 18:00–18:15, WIL C307
Ab initio thermodynamics of adsorbed atomic H at ZnO (10 10) — •Maria E. Stournara1, Sergey V. Levchenko1, Santiago Rigamonti2, Maria Troppenz2, Oliver Hofmann3, Patrick Rinke4, Claudia Draxl2, and Matthias Scheffler1 — 1Fritz-Haber-Institut der MPG, Berlin, DE — 2Faradayweg 4-6 — 3Technische Universität Graz, Graz, AT — 4Aalto University, Helsinki, FI
Zinc oxide (ZnO) is a highly multifunctional material with unique properties and a wide range of applications. To understand atomic hydrogen adsorption on the thermodynamically stable (10 10) surface at realistic H chemical potentials, we combine a first-principles cluster-expansion model with ab initio atomistic thermodynamics. Our study reveals that at coverages below 6%, H atoms adsorb exclusively on surface O. At higher coverages, H adsorbs also on Zn, but there is an excess of O-H over Zn-H at all coverages, except 50% and 100%. Due to an interplay of long- and short-range electrostatic interactions, neighboring O-H/Zn-H pairs form chains along surface -O-Zn- rows, with each chain anchored at the excess O-H, in a wide range of (T,pH2). Any ordering that could occur due to the long-range repulsion between the excess O-H is destroyed at T> 60 K. Our results explain available experimental data and provide detailed microscopic understanding of the ZnO surface properties at realistic (T,pH2) conditions.—This work was supported by the Hybrid Inorganic/Organic Systems (HIOS) CRC of the DFG.