Ti ion valence variation induced by ionizing radiation at TiO2/Si interface

Titanium oxide films are prepared on silicon substrates by the DC reactive sputtering method. The TiO2/Si structures with different TiO2 film thickness are irradiated by electron beams and y-rays. It is found after irradiation that the shift of flat-band voltage △ VFB of MOS structures is very small. There is no evident distortion in the HF C-V curves in comparison with pre irradiation cases. By the XPS analysis, it is found that, after irradiation, the valence of the Ti ion varies; the Ti3+ ion increases and the Ti4+ ion clearly decreases at the TiO2/Si interface. The variation comes mainly from the transition layer between the titanium oxide film and silicon substrate. The mechanism has been discussed in detail. © 2002 Elsevier Science B.V. All rights reserved.link_to_subscribed_fulltex