Abstract

Ti-O-Si mixed oxide films have been grown by reactive ion-beam mixing of Ti/Si interfaces using low energy (3 keV) O-2(+) ions. Shifts in the Ti 2p, Si 2p and O 1s x-ray photoelectron spectroscopy (XPS) bands are observed during O-2(+) bombardment revealing a different formation of chemical species to those of the pure Ti or Si oxides which have been attributed to the growth of a Ti-O-Si mixed oxide at the interface where Ti coordination is different to that of Ti in TiO2. Ultraviolet photoelectron spectroscopy measurements also show a shift of the valence band (VB) edge from 3 to 6 eV which support the change in the Ti local coordination from octahedral to tetrahedral with increasing fluence during O-2(+) bombardment. Angle resolved XPS results show that the in-depth distribution of species is consistent with the formation of a SiO2 outer layer followed by a layer of Ti-O-Si mixed oxide and a third layer of TiO2 when going from the outer surface to the substrate. This complex layer can be specifically attributed to the chemical reaction and the atomic mixing taking place during the interface bombardment with O-2(+). The apparition of species related to Si on the external surface has been qualitatively explained using the existing cascade mixing models.