  Realizing high-performance nanoelectronics requires control of materials at
the nanoscale. Methods to produce high quality epitaxial graphene (EG)
nanostructures on silicon carbide are known. The next step is to grow Van der
Waals semiconductors on top of EG nanostructures. Hexagonal boron nitride
(h-BN) is a wide bandgap semiconductor with a honeycomb lattice structure that
matches that of graphene, making it ideally suited for graphene-based
nanoelectronics. Here, we describe the preparation and characterization of
multilayer h-BN grown epitaxially on EG using a migration-enhanced metalorganic
vapor phase epitaxy process. As a result of the lateral epitaxial deposition
(LED) mechanism, the grown h-BN/EG heterostructures have highly ordered
epitaxial interfaces, as desired in order to preserve the transport properties
of pristine graphene. Atomic scale structural and energetic details of the
observed row-by-row, growth mechanism of the 2D epitaxial h-BN film are
analyzed through first-principles simulations, demonstrating one-dimensional
nucleation-free-energy-barrierless growth. This industrially relevant LED
process can be applied to a wide variety of van der Waals materials.
