Transport measurements had revealed several exotic electronic properties of graphene. The possibility to influence the electronic structure and hence control the conductivity by adsorption or doping with adatoms was crucial in view of electronics applications. Here, it was shown that in contrast to expectation, the conductivity of graphene increases with increasing concentration of vacancy defects, by more than one order of magnitude. A pronounced enhancement of the conductivity was obtained after the insertion of defects by both quantum mechanical transport calculations as well as experimental studies of carbon nano-sheets. This finding was attributed to the defect-induced mid-gap states, which created a region exhibiting metallic behaviour around the vacancy defects. The modification of the conductivity of graphene by the implementation of stable defects was crucial for the creation of electronic junctions in graphene-based electronics devices.

Conductivity Engineering of Graphene by Defect Formation. S.H.M.Jafri, K.Carva, E.Widenkvist, T.Blom, B.Sanyal, J.Fransson, O.Eriksson, U.Jansson, H.Grennberg, O.Karis, R.A.Quinlan, B.C.Holloway, K.Leifer: Journal of Physics D, 2010, 43[4], 045404