Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 89: Oxides and Insulator Surfaces II
O 89.11: Vortrag
Donnerstag, 10. März 2016, 17:45–18:00, H4
Thermal Reduction of Au(111)-Supported Cuprous Oxide Films — •Hanna Fedderwitz1, Claudine Noguera2, Jacek Goniakowski2, and Niklas Nilius1 — 1Carl von Ossietzky Universität Oldenburg, Institut für Physik, D-26111 Oldenburg, Germany — 2CNRS-Sorbonne Universités, UPMC Univ. Paris 06, UMR 7588, INSP, F-75005 Paris, France
Thin Cu2O films with stoichiometric (111)-termination and a band gap of 2.0 eV are prepared by reactive Cu deposition on Au(111) surfaces. Annealing to temperatures above 700 K, both in vacuum and 5*10−6 mbar of oxygen, results in a gradual reduction of the oxide, as monitored by XPS and STM. The reduction process starts off with the appearance of single Cu atoms and small clusters at distinct sites of the Cu2O(111) lattice. At higher temperature, metallic Cu patches develop at the surface, clearly distinguishable from the oxide domains via their deviating atomic and electronic structure. Simultaneously, bare Au(111) regions emerge, which coexist with the Cu and Cu2O domains and continuously increase in size at higher temperature. Additional insight into the Cu2O to Cu transition comes from characteristic changes of the Cu LVV Auger lines, as probed with XPS. The observed reduction behavior of thin-film Cu2O is rationalized with the help of stability diagrams derived from DFT*based ab-initio thermodynamics.