First-principles investigation of graphene on the ferroelectric LiNbO3(001) surface

Recent experiments on graphene-ferroelectric field-effect transistors have introduced an excellent nonvolatility functionality. However, the mechanism of the antihysteresis behavior of graphene on some ferroelectric substrates is controversial. We carry out first-principles calculations to study the interface interaction between graphene and the ferroelectric LiNbO3(001) surface, and find that, when putting a bilayer graphene on a clean surface, the spontaneous polarization field can induce a gap of about 311 meV. If the clean surface is passivated with hydrogen, the electrons are trapped at the interface and nearly screen the polarization field. Our results reveal that the antihysteresis behavior originates from the charge trapping which occurs at the hydrogenated graphene-ferroelectric interface.