Structure of epitaxial thin TiOx films on W(110) as studied by low energy electron diffraction and scanning tunneling microscopy

Abstract

We have studied the growth and structure of thin TiO x films on W͑110͒ using Auger electron spectroscopy, low energy electron diffraction ͑LEED͒, and scanning tunneling microscopy ͑STM͒. The procedure used to grow these films includes the deposition of Ti metal onto the W͑110͒ surface followed by a saturation oxygen exposure. LEED and STM reveal that several different ordered TiO x film structures can result depending upon the initial amount of Ti deposited and the final annealing temperature. Specifically, the oxidation and anneal to 1350 K of a one monolayer ͑ML͒ film of Ti resulted in the formation of a strained ML structure that has a distorted hexagonal lattice and long-range order as observed by LEED and STM. The epitaxial relationship of this 1 ML TiO x structure with the W͑110͒ substrate is found to occur with a Nishiyama-Wassermann orientation.

Interaction of nanostructured metal overlayers with oxide surfaces

“…In some cases, metal deposition is separated from the oxidation process: metal evaporation is conducted in UHV to form epitaxial metal films, which are subsequently introduced to an oxygen atmosphere for growth of oxide films. This technique has been applied to the growth of oxides of Ti [163][164][165], Ce [166], and Fe [167,168]. For example, Fig.…”

Model Studies on CO Oxidation Catalyst Systems: Titania and Gold Nanoparticles

“…Interpretation of the LEED patterns (always featuring two domains as expected) and analysing the observed spot-splitting and streaking led the authors to conclude on the formation of TiO 2 (110) films; as usual, the Ti:O = 1:2 stoichiometry was deduced from XP spectra. Titanium Dioxide on Tungsten, W(110): Herman et al [69] studied the growth of titanium oxide on the densely packed W(110) surface by means of LEED, AES and STM. Again, Ti metal vapour was first condensed on the W surfaces before a saturation exposure of oxygen was applied.…”

Non-Stoichiometric Oxide Surfaces and Ultra-thin Films: Characterisation of TiO2

“…One common technique to form surfaces that are difficult to prepare from single crystals is to grow epitaxial thin films that are sufficiently well ordered to mimic true materials [23]. In particular, thin film metal oxides grown on refractory metals provide a system particularly suited for study of surface properties of these oxides [24][25][26][27], especially for wide bandgap insulating oxides where the ultra-thin films are conductive enough to allow electron spectroscopy and scanning tunnelling microscopy [28].…”