Suppression of the orientation effects on bandgap in graphene nanoribbons in the presence of edge disorder

This letter shows that a moderate degree of edge disorder can explain the fact that the experimentally measured bandgaps of graphene nanoribbons (GNRs) do not depend on orientation. We argue that GNRs actually behave similarly to Anderson insulators and the measured bandgaps should thus be interpreted as quasi-mobility edges. Calculations in the tight binding approach reveal that in the presence of edge disorder, quasi-mobility edge and electronic structures become independent of orientation and that quasi-mobility edge follows a quasi-universal law similar to experimental data, although with different parameters. (c) 2008 American Institute of Physics.