Preparation and characterization of epitaxial titanium oxide films on Mo(100) Available to Purchase

Ultrathin (<100 Å) titanium oxide films have been synthesized on the Mo(100) surface and characterized using various surface science techniques. Epitaxial $TiO2$ films of varying film thickness were prepared by evaporating titanium in an oxygen background $(5×10−7 Torr)$ between 500 and 700 K, followed by annealing to 900–1200 K. The growth, composition, and structure of the $TiO2$ films have been investigated using ion scattering spectroscopy (ISS), x-ray photon spectroscopy (XPS), Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and scanning tunnel microscopy (STM). A (2√×√)R45° LEED pattern was observed after annealing 4.7, 15, and 90 Å film thicknesses to 900–1200 K in vacuum. LEED and STM results show that the $TiO2$ films order along the 〈010〉 and 〈001〉 directions of the Mo(100) substrate. XPS data show that unannealed titanium oxide films exhibit only the $Ti4+$ valence state, whereas annealed titanium oxide films are partially reduced and exhibit the $Ti3+$ and $Ti2+$ states, as well. ISS measurements of unannealed titanium oxide films show that $TiO2$ films wet the Mo(100) surface well.