Single electron tunneling as a possible conduction mechanism in diamond   like carbon film
  Nonlinear current voltage characteristics and in some cases also step like characteristics were observed in diamond like carbon films. We suggest that the transport mechanism is tunneling between conducting nanoparticles in the films and the observation of step like structures is a manifestation of Coulomb blockade found for the first time in these films. We point out that the origin of similar current voltage characteristics observed in other carbon structures can be also Coulomb blockade phenomenon. 
S.S. Tinchev, S. Alexandrova, E. Valcheva