Heteroepitaxial film of monolayer graphene/monolayer h-BN on Ni(111)

Heteroepitaxial multilayers, consisting of graphene/hexagonal boron nitride (h-BN) films on Ni(111), have been investigated by means of vibrational spectroscopy, low energy electron diffraction and Auger electron spectroscopy. Vibrational spectra of the heteroepitaxial film show the appearance of transverse optical (TOperpendicular to) modes with out-of-plane polarization at 100 meV of the monolayer h-BN, in contrast to the softening phonon at 90 meV on the pristine system of monolayer h-BN on Ni(111). The findings strongly suggest that the interfacial bonds between h-BN and Ni(111) weaken due to the formation of monolayer graphene.