How transparent is graphene? A surface science perspective on remote epitaxy

Abstract: Remote epitaxy is the synthesis of a single crystalline film on a graphene-covered substrate, where the film adopts epitaxial registry to the substrate as if the graphene is transparent. Despite many exciting applications for flexible electronics, strain engineering, and heterogeneous integration, an understanding of the fundamental synthesis mechanisms remains elusive. Here we offer a perspective on the synthesis mechanisms, focusing on the foundational assumption of graphene transparency. We highlight challenges for quantifying the strength of the remote substrate potential that permeates through graphene, and propose Fourier and beating analysis as a bias-free method for decomposing the lattice potential contributions from the substrate, from graphene, and from surface reconstructions, each at different frequencies. We highlight the importance of graphene-induced reconstructions on epitaxial templating, drawing comparison to moir\'e epitaxy. Finally, we highlight the role of the remote potential in tuning surface diffusion and adatom kinetics on graphene. Tuning the surface diffusion length is crucial in navigating the competition between remote epitaxy and defect-seeded mechanisms like pinhole epitaxy.