Charge Transport in Mesoscopic Carbon Network Structures
- PDF / 4,463,243 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 57 Downloads / 279 Views
Charge Transport in Mesoscopic Carbon Network Structures V. Ksenevich1 , J. Galibert 2 , V. Samuilov1,2,3, Y.-S. Seo3 , J. Sokolov3 , M. Rafailovich3 1 Department of Physics, State University of Belarus, 220080, Minsk, Belarus 2 Laboratoire National des Champs Magnetiques Pulses, F-31432 Toulouse CEDEX 4, France 3 Department of Materials Science, SUNY at Stony Brook, Stony Brook, NY 11794, USA ABSTRACT The charge transport and quantum interference effects in low-dimensional mesoscopic carbon networks prepared using self-assembling were investigated. The mechanism of conduction in low-dimensional carbon networks was found to depend on the annealing temperature of the nitrocellulose precursor. The charge transport mechanism for carbon networks obtained at Tann=750 0 C was found to be the hopping conductivity in the entire investigated temperature range. The Coulomb gap near the Fermi level in the density of states was observed in the investigated carbon networks. The width of the Coulomb gap was found to be decreased with the annealing temperature of the carbon structures. The crossover from the strong localization to the weak localization regime of the charge transport in the carbon structures, obtained at Tann=950 0 C and Tann=1150 0 C, was observed in the temperature range T>100 K and T>20 K, respectively.
INTRODUCTION High temperature treatment of polymer precursors in vacuum results in different carbon structures synthesis, like carbon fibers [1-3], carbon-black polymer composites [4,5], porous aerogels [1,6] and low dimensional carbon networks [7,8]. These disordered carbon matrixes have been used as model materials for electronic transport phenomena investigation dependently on the annealing temperature, which was found to determine the degree of disorder. As a result different quantum phenomena can be observed: strong localization, hopping conductivity, quantum interference, weak localization, metal-insulator (MI) transition. These carbon materials could be considered as nanostructured materials with different internal morphology. We have developed a simple approach of self-organized fabrication of two dimensional mesoscopic networks with the feature size down to 50 nm and the size of the cells of the order of 500 nm. Two dimensional mesoscopic network-like carbon structures were produced by high temperature annealing of nitrocellulose precursors [8].
EXPERIMENTAL DETAILS The technique is based on the self-organized patterning in a thin layer of complex liquid diluted nitrocellulose solution (1% nitrocellulose in amyl acetate with ethyl alcohol as a solvent) in the presence of humid atmosphere. The sub-micron sized water droplets were trapped at the surface and self assemble in regular aggregates. The polymer was found to precipitate at the water-polymer solution interface, forming a layer encapsulating the droplets and preventing their coalescence. After the evaporation of the solvent the resulting networks were transferred onto Y8.9.1
insulating substrates. The final carbon structures (Fig.1) were produc
Data Loading...
