Electronic transport in monolayer graphene nanoribbons produced by chemical unzipping of carbon nanotubes

We report on the structural and electrical properties of graphene nanoribbons (GNRs) produced by the oxidative unzipping of carbon nanotubes. GNRs were reduced by hydrazine at 95 degrees C and further annealed in Ar/H(2) at 900 degrees C; monolayer ribbons were selected for the fabrication of electronic devices. GNR devices on Si/SiO(2) substrates exhibit an ambipolar electric field effect typical for graphene. The conductivity of monolayer GNRs (similar to 35 S/cm) and mobility of charge carriers (0.5-3 cm(2)/V s) are less than the conductivity and mobility of pristine graphene, which could be explained by oxidative damage caused by the harsh H(2)SO(4)/KMnO(4) used to make GNRs. The resistance of GNR devices increases by about three orders of magnitude upon cooling from 300 to 20 K. The resistance/temperature data is consistent with the variable range hopping mechanism, which, along with the microscopy data, suggests that the GNRs have a nonuniform structure. (C) 2009 American Institute of Physics. [doi:10.1063/1.3276912]