Remote graphene doping

Graphene, a zero-bandgap semiconductor, attracted much interest for its mechanical, optical, and electronic properties. From our point of view, the most exciting feature is the possibility to control its electronic properties, i.e., the type of charge carriers and their concentration, by the external electric field. We investigate ways of its remote doping by irradiation by X-ray or electron beam. 

Electron Beam Doping

 


We employ the low energy electron beam irradiation to induce both n- and p-doping in the graphene layer. The type of dominant charge carriers induced in the graphene depends on the applied gate voltage. Irradiation of the graphene layer at the gate voltages higher (lower) than a specific threshold voltage VT value results in negative (positive) graphene doping. By designing the irradiation protocol a desired CNP position can be set. 

V. Stará, P. Procházka, D. Mareček, T. Šikola, J. Čechal: Nanoscale 10, (2018), 17520. 

X-Ray Doping



We have shown that the X-ray irradiation at the zero applied gate voltage causes very strong negative doping of graphene, which is explained by X-ray radiation induced charging of defects in the gate dielectric. The induced charge can be neutralized and compensated if the graphene device is irradiated by X-rays at a negative gate voltage: the charge neutrality point shifts back to zero voltage. 

P. Procházka, D. Mareček, Z. Lišková, J. Čechal, T. Šikola, Sci. Rep. 7 (2017), 563.