Cross-linked silicon based polymer nano-wire formation by high energy charged particles

High energy charged particles penetrating into silicon based polymer materials cause non-homogeneous cross-linking in the nanospace along the particle trajectories, giving nano-gels (nano-wires) of polymers with cylindrical structures of regular length and thickness. Polycarbosilanes with a variety of molecular weights were used as the target polymer materials in the present study, and the preparation of nano-wires based on cross-linked polycarbosilanes were demonstrated. The molecular weight of the polymers is one of the factors to determine the nano-wire thickness which has been controlled precisely from 5.4–6.5 nm as the radii of the cross section by the present technique upon irradiation by 388 MeV Ni ions. Drastic increase in the radii is observed with an increase in the deposited energy density of incident charged particles. The size dependence is well interpreted by a model of radial energy distribution in the ion track.