Lattice Relaxation at the Interface of Two-Dimensional
Crystals: Graphene and Hexagonal Boron-Nitride
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Abstract
Heteroepitaxy of two-dimensional
(2D) crystals, such as hexagonal boron nitride (BN) on graphene (G),
can occur at the edge of an existing heterointerface. Understanding
strain relaxation at such 2D laterally fused interface is useful in
fabricating heterointerfaces with a high degree of atomic coherency
and structural stability. We use in situ scanning tunneling microscopy
to study the 2D heteroepitaxy of BN on graphene edges on a Ru(0001)
surface with the aim of understanding the propagation of interfacial
strain. We found that defect-free, pseudomorphic growth of BN on a
graphene edge “substrate” occurs only for a short distance
(<1.29 nm) perpendicular to the interface, beyond which misfit
zero-dimensional dislocations occur to reduce the elastic strain energy.
Boundary states originating from a coherent zigzag-linked G/BN boundary
are observed to greatly enhance the local conductivity, thus affording
a new avenue to construct one-dimensional transport channels in G/BN
hybrid interface