Surface Structure of V₂O₃(0001) – A Combined I/V-LEED + STM Study

Using I/V-LEED and scanning tunneling microscopy we have investigated the surface structure of ~100Å thick V2O3(0001) films on Au(111). Both methods clearly show that the surface is terminated by a layer of vanadyl groups. I/V-LEED quantitative structure determination applied to differently prepared films always leads to a Pendry R-factor for the V=O termination close to 0.11 while the R-factor for a reconstructed O3 termination is always larger than 0.2 and increases with increasing dataset size. These results are at variance with a recent publication by Window et al. [ Phys. Rev. Lett. 114, 2015, 216101 ] in which the authors propose that the V2O3(0001) surface is terminated by a reconstructed O3 structure. Surface oxidation experiments also contradict the conclusions of Window et al. since oxidation leads to a previously identified structure with a (√3x√3)R30° LEED pattern which is not expected for oxidation of an O3 terminated surface. In the course of the I/V-LEED calculations the individual Debye temperatures of the surface atoms were determined as part of the structural optimization procedure. We show that this approach is superior to the kinematical analysis of temperature dependent LEED measurements