Intercalation-assisted remote epitaxy of GaN on epitaxial graphene

Metalorganic chemical vapor deposition (MOCVD) of GaN on pristine epitaxial graphene formed on SiC is hindered by the low energy van der Waals surface, which suppresses nucleation and promotes island growth. Here, we demonstrate an intercalation-assisted approach to modify the graphene/SiC interface and influence GaN nucleation behavior via a remote epitaxy process. Using a pulsed MOCVD technique, a ∼4 nm GaN interlayer was first intercalated beneath the epitaxial graphene followed by subsequent epitaxial growth of the GaN film. Intercalation promotes a high nucleation density, enabling the growth of a coalesced 1.5 μm-thick epitaxial GaN film with step-flow morphology. Cross-sectional scanning transmission electron microscopy reveals atomic alignment between the GaN epilayer and the intercalated GaN across the graphene interlayer, maintaining epitaxial registry. The weak interfacial bonding enables mechanical exfoliation of the GaN film to form a thin, freestanding membrane. These results demonstrate that intercalation can provide an alternative pathway to engineer the graphene/substrate interface to facilitate remote epitaxy without the need for graphene layer transfer.