Tunneling current between structural elements of thin graphene/nanotube films

Based on the constructed atomistic models of graphene/nanotube films with different numbers of nanotubes in supercells, we carried out in silico studies of the regularities of the nonuniform density distribution, which determine the presence of an island structure in such films. As a result of quantum molecular dynamics modeling, it is found that thin tubes of subnanometer diameter are enveloped in graphene sheets, which makes them energetically stable and stable. We also studied tunneling contacts between individual film fragments that are not covalently bound, in particular, between graphene sheets with different topologies of contacting zigzag and armchair edges, depending on the distance between them, and between tubes of different chiralities, including (6,3), (4,4), (6,5), (12,6) and (16,0). It is found that the tunnel contacts of tubes with a semiconductor type of conductivity are characterized by the presence of voltage intervals with a negative differential resistance in the I – V characteristic. Such voltage intervals are not observed at all for tubes with a metallic character of conductivity. The new knowledge obtained is important for assessing the electrical conductivity of such films, two-thirds of which are semiconductor tubes.