Effect of Surface Termination on Charge Doping in Graphene/BiFeO3(0001) Hybrid Structure

Electrostatic charge doping in graphene by ferroelectric polarization is an intriguing avenue for graphene-based nanoelectronic devices. Here, on the basis of the thermodynamically stable BiFeO3(0001) surfaces, we present first-principles calculations to study the influence of surface termination on interface chemistry and charge doping in a graphene/BiFeO(3 )hybrid system. Our results reveal that the doping type and carrier density in graphene are not directly determined by the polarization direction of the ferroelectric substrate but by the electronegativity difference between graphene and the surface termination of the BiFeO3, substrate. This finding indicates that the intrinsic resistance change in graphene on the ferroelectric substrate can show proper-hysteresis or antihysteresis behavior, depending on the surface terminations and hence on the particular chemical conditions. In addition, we find that highly spin-polarized (similar to -31%) Dirac fermions in graphene can be induced by depositing on the insulating BiFeO3(0001) negative surface terminated by a -Bi-O-3-Fe trilayer. Besides shedding light on the underlying mechanism of charge doping effect in the graphene/ferroelectric interfaces, our results also put forward practical strategies for developing/improving advanced functionalities of the graphene-based ferroelectric field-effect devices.