Conductivity of nanometer-sized ion tracks in diamond-like carbon films

Abstract

Amorphous diamond-like carbon films were irradiated with high-energy heavy ions like 1 GeV uranium or 340 MeV gold. The large energy deposition along the ion track leads to a transformation of the material from insulating diamond-like to conducting graphite-like carbon. The ion tracks form thin straight channels (nanowires) with a diameter of approximately 8 nm and a conductivity of the order of 1–10 S/cm. The conductivity in the tracks is up to eight orders of magnitude larger than in the surrounding material. The surface topography and the conduction properties of these channels were studied with an atomic force microscope.

Microstructure evolution and the modification of the electron field emission properties of diamond films by gigaelectron volt Au-ion irradiation

“…Effect of Au-ion irradiation on the MCD films Figure 1 shows that the 2.245 GeV Au-ion irradiation (8.4x10 13 ions/cm 2 ) induced dramatic changes in the surface morphology of the microcrystalline diamond (MCD) films. The size of the grains was reduced from 500-900 nm for pristine MCD films ( Fig.…”

“…The MCD and UNCD diamond films, around 300 nm in thickness, were subjected to 2.245 GeV Au-ion irradiation from the Universal linear accelerator (UNILAC) at GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany, with fluences of 8.4×10 13 21 Therefore, the Au-ions will pass through the diamond films and get buried deep in the substrate for all the samples. There is no doping effect due to the Au-ion irradiation.…”

“…Much work has been carried out to improve the field emission of microcrystalline and nanocrystalline diamond by the ion implantation process. 10,11 Moreover, many reports have discussed the effects of ion beam irradiation on the characteristics of carbon based materials such as type IIa diamond, 12 diamond-like carbon films, 13 taC, 14 graphite 15 and polycrystalline CVD diamond films. [16][17][18] Furthermore, Pandey et al 19 and Koinkar et al 20 have studied the field emission enhancement by swift heavy ion irradiation in CVD diamonds; nevertheless, the mechanism for the modification of these characteristics remains unclear.…”

“…For the microcrystalline diamond (MCD) films, Au-ion irradiation with a fluence of approximately 8.4×10 13 ions/cm 2 almost completely suppressed the EFE properties of the films. Post-annealing the Au-ion irradiated MCD films at 1000 • C for 1 h effectively restored these properties.…”

Surface morphology and phase stability of titanium foils irradiated with 136MeV 136Xe

“…Hillocks are formed when material flows out of the region of the ion track during the hot stage of the track formation process [10]. Hillock formation is thought to be a result of interplay among surface movement of atoms and the effects of sputtering [11].…”