Field-induced metal diffusion into C_60 thin films

摘要

We report the evolution in time of d.c. conductivity of polycrystalline thin films of C_60 at different temperatures and under various applied voltages. All films show a clear semiconducting behaviour. The initial resistivity (at T=14- deg C) and the activation energy are rho approx 10~5 omega cm and E_a approx 0.5 eV, respectively. For various types of metallic electrodes M (M-Au, Ag or In), a field-induced conductivity increase by several orders of magnitude and an activation energy decrease are observed. The results are interpreted in terms of electrode metal diffusion into the film.