Effect of Bombarding Ion-Species on Surface Electric Properties of TiO₂

Abstract

Surface electric resistance and chemical state have been investigated for TiO₂ bombarded with 8keV ions (B⁺, C⁺, N⁺, O⁺, F⁺ and Ne⁺ ions). The tendencies of the resistivity change by the ion irradiation are divided into three groups; 1) no chemical change but significant decrease of electric resistance is observed (B⁺ and C⁺ ions), 2) neither chemical change nor decrease of electric resistance is observed (N⁺, O⁺ and F⁺ ions), and 3) both chemical change and decrease of electric resistance are observed (Ne⁺ ions). For the Ne⁺ ion irradiation, a Ti3d-derived new band appears near the Fermi level. It suggests that a part of electrons in its level becomes carrier of the conductivity. On the other hand, the Fermi edge in the UPS spectra remains unchanged for the B⁺ and C⁺ ion irradiations, which implies that carrier of the conductivity is positive holes created by the implanted ions.