Berlin 2015 – scientific programme

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DS: Fachverband Dünne Schichten

DS 29: Oxide and insulator surface: Structure, epitaxy and growth (joint session with O)

DS 29.4: Talk

Wednesday, March 18, 2015, 15:45–16:00, MA 042

Atomic structure and electronic properties of Cu₂O(111) films — •Boris Groß, Hanna Fedderwitz, Hendrik Sträter, and Niklas Nilius — Carl-von-Ossietzky Universität Oldenburg, Carl-von-Ossietzky Str. 9-11, 26129 ,Oldenburg

Atomically flat films of cuprous oxides were prepared by Cu deposition in oxygen onto an Au(111) surface, and analyzed by XPS, electron diffraction and STM. Depending on the preparation conditions, different surface reconstructions are obtained. Whereas the low-temperature structures have no analogy to respective bulk phases and are governed by interactions with the metal support, the high-temperature films have a similar atomic configuration as bulk-cut Cu₂O(111). STM conductance spectroscopy reveals the pronounced 2.0 eV band gap of the oxide, in addition to an unoccupied surface state that occurs in the high-temperature phase. Field-emission resonances that govern the high-energy part of the STM spectra are used to monitor local variations in the work function of the system. Given their high crystallographic quality, our Cu₂O films provide an ideal starting point to explore the defect landscape and optical properties for this reference material for photo-catalysis and photovoltaics.