Two-dimensional TiOx nanostructures on Au(111): a Scanning Tunneling Microscopy and Spectroscopy investigation
arXiv:1509.02363 · doi:10.1088/2053-1583/2/4/045011
Abstract
We investigated the growth of titanium oxide two-dimensional (2D) nanostructures on Au(111), produced by Ti evaporation and post-deposition oxidation. Scanning tunneling microscopy and spectroscopy (STM and STS) and low-energy electron diffraction (LEED) measurements characterized the morphological, structural and electronic properties of the observed structures. Five distinct TiO\sub{x} phases were identified: the \emph{honeycomb} and \emph{pinwheel} phases appear as monolayer films wetting the gold surface, while nanocrystallites of the \emph{triangular}, \emph{row} and \emph{needle} phases grow mainly over the honeycomb or pinwheel layers. Density Functional Theory (DFT) investigation of the honeycomb structure supports a structural model based on a Ti-O bilayer having stoichiometry. The pinwheel phase was observed to evolve, for increasing coverage, from single triangular crystallites to a well-ordered film forming a superstructure, which can be interpreted within a moirÃ\c{opyright}-like model. Structural characteristics of the other three phases were disclosed from the analysis of high-resolution STM measurements. STS measurements revealed a partial metallization of honeycomb and pinwheel and a semiconducting character of row and triangular phases.
13 pages, 10 figures