We have used scanning gate microscopy to explore the local conductivity of a current-annealed graphene flake. A map of the local neutrality point (NP) after annealing at low current density exhibits micron-sized inhomogeneities. Broadening of the local e-h transition is also correlated with the inhomogeneity of the NP. Annealing at higher current density reduces the NP inhomogeneity, but we still observe some asymmetry in the e-h conduction. We attribute this to a hole doped domain close to one of the metal contacts combined with underlying striations in the local NP.
@article{arxiv.0911.3832,
title = {Scanning gate microscopy of current-annealed single layer graphene},
author = {M. R. Connolly and K. L. Chiou and C. G. Smith and D. Anderson and G. A. C. Jones and A. Lombardo and A. Fasoli and A. C. Ferrari},
journal= {arXiv preprint arXiv:0911.3832},
year = {2010}
}