Local electrical stress-induced doping and formation of monolayer graphene P-N junction

We demonstrated doping in monolayer graphene via local electrical stressing. The doping, confirmed by the resistance-voltage transfer characteristics of the graphene system, is observed to continuously tunable from N-type to P-type as the electrical stressing level (voltage) increases. Two major physical mechanisms are proposed to interpret the observed phenomena: modifications of surface chemistry for N-type doping (at low-level stressing) and thermally-activated charge transfer from graphene to SiO2 substrate for P-type doping (at high-level stressing). The formation of P-N junction on two-dimensional graphene monolayer is demonstrated with complementary doping based on locally applied electrical stressing. (C) 2011 American Institute of Physics. [doi:10.1063/1.3593131]