DC CONDUCTION IN DIAMOND-LIKE CARBON-FILMS OBTAINED BY LOW-ENERGY CLUSTER BEAM DEPOSITION

Carbon films have been obtained by low-energy cluster beam deposition. Clusters of different size distributions centered around C-n = 900, 6 0, 20 have been selected because of their very different mean hybridiz ation: high sp(2) content for C-900, highly sp(3) for C-20, C-60 being intermediate. Thus, three types of film have been grown and their de conductivity has been investigated in the temperature range 80-473 K. The temperature dependence of the conductivity is explained by carrier hopping and percolation theory. Hopping transport occurs through pi s tates randomly distributed in energy and in the solid. The pi state de nsities determined near the Fermi level show that the three types of f ilm remember the hybridization of the different mean free cluster size . Conduction properties of the film are compared with those of a-C fil ms prepared by other techniques.