Titanium oxide films on Si(100) deposited by e-beam evaporation

Abstract

Titanium oxide films with a thickness of a 400 nm were deposited on p-type Si(100) at room temperature by e-beam evaporation, and titanium dioxide was evaporated in oxygen environment at a pressure of 2×10−6–4×10−5 Torr. Effects of oxygen flow rate (FO2) on the properties of the films, such as surface roughness, composition, and chemical states, have been investigated. The root-mean-square surface roughness of the films increased with increasing FO2 up to 20 sccm, and then decreased over 20 sccm. X-ray diffraction patterns show that the titanium oxide films are amorphous. Oxygen resonance backscattering spectroscopy shows that all films are oxygen rich, i.e., relative atomic ratio (CO/CTi) of the films ranged from 2.05 to 2.25. But the x-ray photoelectron spectroscopy (XPS) analysis shows that the titanium oxide films were oxygen deficient. The ratio of oxygen to titanium (CO2/CTi) of the films calculated by XPS ranged from 1.82 to 1.93. XPS shows that there exist only Ti3+ and Ti4+ charge states in the film. Ti4+ states of the films are nearly constant at 0.47 up to O2 flow rate of 20 sccm, and then slightly increase with increasing O2 flow rate. Although rutile TiO2 is used as a starting material, titanium K-edge x-ray absorption near-edge spectroscopy (XANES) spectra show that the structure of the TiO2−x films grown in oxygen environment are amorphous. The Ti K-edge XANES spectra from the films is the same regardless of FO2.