Functionalization of exfoliated graphene by grafting aryl groups

We studied the transport properties of aryl functionalized exfoliated graphene. For the functionalization the graphene devices were immersed in a solution of diazonium salt. The attachment of aryl free radical to the basal carbon atoms changes the hybridization of the graphitic atoms from sp2 to sp3 thereby~modifying the lattice's electronic structure. We observe that this opens a Coulomb gap at low temperatures and transport measurements indicate a variable range hopping mechanism. In suspended graphene, which allows for functionalization on both sides, we observe a large transport gap.