Electrical conductivity of cluster-assembled carbon/titania nanocomposite films irradiated by highly focused vacuum ultraviolet photon beams

We investigated the electrical transport properties of nanostructured carbon and carbon/titanium oxide nanocomposite films produced by supersonic cluster beam deposition and irradiated by highly focused vacuum UV photon beam. We have observed a relevant increase of the density of states at Fermi level, suggesting that the films acquire a "metallic" character. This is confirmed by the increment of the conductivity of four orders of magnitude for pure nanostructured carbon films and at least eight orders of magnitude for films containing 9 at. % of titanium. A partial reversibility of the process is observed by exposing the modified films to molecular oxygen or directly to air. We demonstrate the capability of writing micrometric conductive strips (2-3 mu m width and 60 mu m length) and controlling the variation of the conductivity as a function of the titanium concentration.