Reading and writing charge on graphene devices
  We use a combination of charge writing and scanning gate microscopy to map and modify the local charge neutrality point of graphene field-effect devices. We give a demonstration of the technique by writing remote charge in a thin dielectric layer over the graphene-metal interface and detecting the resulting shift in local charge neutrality point. We perform electrostatic simulations to characterize the gating effect of a realistic scanning probe tip on a graphene bilayer and find a good agreement with the experimental results. 
M. R. Connolly, E. D. Herbschleb, R. K. Puddy, M. Roy, D. Anderson, G.   A. C. Jones, P. Maksym, and C. G. Smith
cond-mat.mes-hall