Activated Metal Deposition and Oxide Growth on Semiconductors: TiO2(111)-2x1. (Reannouncement with New Availability Information).

摘要

Thin titanium dioxide films grown on metal and semiconductor substrates have attracted particular interest because of promising applications in the field of catalysis for organic and inorganic molecules, optical coatings for enhancing the transmission or reflection of visible and infrared light, and high-temperature-resistant semiconductor devices. In this paper we present a detailed x-ray photoemission study of the room-temperature growth of thin TiO2 layers under ultrahigh vacuum conditions on cleaved Si(111)-2x1 surfaces. The ti oxide films were grown by the slow sublimation of Ti from a high-purity source in an activated oxygen environment. By analyzing the Si 2p, Ti 2p, and O 1s core emission line shapes and intensities and the valence-band spectra as a function of increasing TiO2 thickness, we have characterized the quality of the thin films and such interface properties as chemical reactivity, substrate band bending, interface abruptness, and the overlayer growth mode. Our results show that all Ti atoms are in the 4+ oxidation state with a very low density of states near the Fermi level. A thin Si oxide interlayer forms at low coverage but is subsequently covered by the TiO2 overlayer which grows in a nearly uniform way.