Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 28: Adsorption an Oberfl
ächen III

O 28.3: Vortrag

Donnerstag, 27. März 2003, 11:45–12:00, FOE/ANOR

Structure and stability of polar O-terminated ZnO (0001) surfaces: Using CO as a probe molecule — •Bernd Meyer and Dominik Marx — Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany

Polar surfaces of ionic crystals are usually stabilized by massive reconstructions, loss of surface ions or the adsorption of charged species. However, from LEED and other diffraction experiments it was concluded that the polar O-terminated (0001) surface of ZnO can be prepared in a clean, unreconstructed state.

With the present study we demonstrate that using the binding energy of a probe molecule, CO, is a reliable tool to validate structural models for such complex oxide surfaces. Combining first-principles calculations with advanced molecular beam techniques we are able to provide conclusive evidence that the polar O-terminated surface of ZnO is either reconstructed or hydrogen covered. Also our first-principles calculation of the stability regions of different surface structures in the surface phase diagram seriously questions the existence of a clean, unreconstructed O-terminated ZnO (0001) surface.