Titanium oxide films on Si(100) deposited by electron-beam evaporation at 250 °C

Abstract

Titanium oxide films with a thickness of a 400 nm were deposited on p-type Si(100) at 250 °C by electron-beam evaporation where titanium dioxide was evaporated in oxygen environment at a pressure of 2×10−6–4×10−5 Torr. Effects of oxygen flow rate (FO2) between 0 and 40 sccm on properties such as crystallinity, surface roughness, and chemical states of the films have been investigated. Oxygen resonance backscattering spectroscopy shows that all films are oxygen rich, i.e., the ratio of oxygen to titanium of the films ranged from 2.25 to 2.3. X-ray diffraction patterns show that these films grown at 250 °C are polycrystalline of anatase TiO2. Ti K-edge x-ray absorption near-edge spectroscopy (XANES) spectra show that the films have mixed phases of anatase and rutile TiO2. More than 70% of the films is anatase TiO2 and its proportion of the films is decreased with increasing FO2. XANES spectra from the films grown at FO2=0 sccm are very similar to that of the powdered anatase TiO2. X-ray photoelectron spectroscopy indicates that there exist Ti2+, Ti3+, and Ti4+ charge states in the film grown at FO2≦10 sccm but there exist only Ti3+ and Ti4+ charge states in the film grown at FO2>10 sccm.