We report and analyze low-temperature measurements of the conductance of partially disordered reduced graphene oxide, finding that the data follow a simple crossover scenario. At room temperature, conductance is dominated by two-dimensional (2D) electric field-assisted, thermally-driven (Pollak-Riess) variable-range hopping (VRH) through highly-disordered regions. However, at lower temperatures T, we find a smooth crossover to follow the exp(-E_0/E)^(1/3) field-driven (Shklovskii) 2D VRH conductance behaviour when the electric field E exceeds a specific crossover value E_C (T)_2D = (E_a E_0^(1/3) /3)^(3/4) determined by the scale factors E_0 and E_a for the high-field and intermediate field regimes respectively. Our crossover scenario also accounts well for experimental data reported by other authors for three-dimensional disordered carbon networks, suggesting wide applicability.
@article{arxiv.1305.0315,
title = {Conductance of partially disordered graphene: Crossover from temperature-dependent to field-dependent variable-range hopping},
author = {C. Y. Cheah and C. Gómez-Navarro and L. C. Jaurigue and A. B. Kaiser},
journal= {arXiv preprint arXiv:1305.0315},
year = {2013}
}
Comments
8 pages, 4 figures; Corrected typo in Table 1, value in the last row of column E_a should be 21.74