NEAR-SURFACE DEFECTS CREATED BY 355-NM LASER IRRADIATION OF RUTILE

Sintered disks of TiO2 (rutile) have been exposed to the beam of a 355 nm laser. X-ray photoelectron spectroscopy studies show that the strong energy deposition at the surface is responsible for the formation of Ti3+ ions down to a depth of 0.4 mu m. The presence of these ions produces a large decrease in the electrical resistivity from 10(9) Omega cm in nonirradiated TiO2 to 10 Omega cm after laser treatment. Temperature dependent resistance measurements indicate that the creation of Ti3+ ions leads to the formation of energy levels in the gap and to a hopping-driven conduction at room temperature.