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 stro ng energy deposition at the surface is responsible for the formation o f Ti3+ ions down to a depth of 0.4 mu m. The presence of these ions pr oduces a large decrease in the electrical resistivity from 10(9) Omega cm in nonirradiated TiO2 to 10 Omega cm after laser treatment. Temper ature 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.