Electrical conduction in nanostructured carbon films produced by supersonic cluster beam deposition

We present a study on electrical conduction in nanostructured carbon films produced by deposition of a supersonic beam of neutral carbon clusters. The electrical transport properties have been investigated by measuring the electrical conductance both in-situ, during the film deposition, and ex-situ, after the film exposure to ambient air. The I-V characteristic indicates a strict ohmic behavior all over the measured electric field range up to (2 kV/cm). Changes in the electrical conductance have been observed due to gas adsorption-desorption mechanisms. The exposure to air leads to a passivation of the film with an increase of resistivity up to ∼ 0.1 GΩ.cm. Current-temperature characteristics measured in vacuum in the temperature range 150-400 K, both in-situ and ex-situ, indicate a thermally activated conductivity with energy of ∼ 0.3 eV.