The role of oxygen partial pressure and annealing temperature on the formation of W=O bonds in thin WO_3 films

摘要

Thin films of tungsten oxide were deposited onto silicon substrates using reactive rf sputtering. The structure of the films is strongly dependent on the conditions of deposition and post-treatment. Important issues are the influences of oxygen pressure during deposition and of annealing temperature. We used x-ray photoelectron spectroscopy to investigate the in-depth composition of the films. The most surface sensitive O 1s core level spectra are made up of two structures, one generated by photoelectrons emitted from oxygen atoms in WO_3 (O-W-O) and other at lower energy generated by the photoelectrons emitted from oxygen atoms located at the boundary of the grains (W-O).