We investigate the density and temperature-dependent conductance of graphene nanoribbons with varying aspect ratio. Transport is dominated by a chain of quantum dots forming spontaneously due to disorder. Depending on ribbon length, electron density, and temperature, single or multiple quan- tum dots dominate the conductance. Between conductance resonances cotunneling transport at the lowest temperatures turns into activated transport at higher temperatures. The density-dependent activation energy resembles the Coulomb gap in a quantitative manner. Individual resonances show signatures of multi-level transport in some regimes, and stochastic Coulomb blockade in others.
@article{arxiv.1107.4326,
title = {Coulomb Gap in Graphene Nanoribbons},
author = {S. Dröscher and H. Knowles and Y. Meir and K. Ensslin and T. Ihn},
journal= {arXiv preprint arXiv:1107.4326},
year = {2011}
}