Electronic microstructure in the implant layer of ion implanted polymers

The mechanical and electronic properties of ion implanted polymers have been determined to be a function of ion dose, energy and beam current. In previous studies the implant layer was assumed to be isotropic. In an earlier report we speculated that the implant layer was not isotropic, based on a temperature coefficient of resistivity (TCR) that could not be explained by a single structural configuration[1]. In this study we examined the effect of etching the surface layer, decreasing polymer thickness, on the TCR to determine which part of the implant layer contributed to the various mechanisms of conduction. We have concluded that there are at least two mechanisms responsible for conduction, Mott three dimensional variable range hopping (VRH), and Mott one dimensional VRH. It is possible that other theories may be more correct (e.g. crossover to ES-VRH at low temperatures) since many theories predict the same temperature dependence. We found that conduction with the Mott one dimensional VRH exists at the bottom of the implant layer.