The Atomic Structure of a Metal-Supported Two-Dimensional Germania Film

Scanning tunneling microscopy (STM) images of two-dimensional silica films have recently provided new insight into the structural configurations of amorphous networks [1]. Similar investigations of other known glass formers, such as germania, are needed to establish a more complete understanding of amorphous network structures. Here we present the growth and characterization of two-dimensional germania films. Germanium oxide monolayer films were grown on Ru(0001) by physical vapor deposition and subsequent annealing in oxygen. We obtain a comprehensive image of the germania film structure by combining LEED-IV (Low energy electron diffraction) and ab initio density functional theory (DFT) analysis with high-resolution scanning tunneling microscopy (STM) imaging. STM images show the hexagonal network and domain boundary structures in atomically flat germania films. For quantitative LEED, the best agreement has been achieved with DFT structures where the germanium atoms sit preferentially on the top and fcc hollow sites of the Ru(0001) substrate.

[1] . Lichtenstein, C. Büchner, B. Yang, S. Shaikhutdinov, M. Heyde, M. Sierka, R. Wlodarczyk, J. Sauer, H.-J. Freund, Angew. Chem. Int. Ed. 51, 404 (2012)