Atomic-scale confinement at the graphene/SiC interface: A platform for novel two-dimensional nanomaterials

Novel two-dimensional nanomaterials have attracted broad interest for both fundamental physics and next-generation device applications because the atomic-layer limit gives rise to properties that are absent in their bulk counterparts. However, conventional approaches for synthesizing atomically thin metals and related non-van der Waals materials are often limited by small lateral dimensions, poor coverage uniformity, and insufficient air stability. Epitaxial graphene on silicon carbide (EG/SiC) serves as a powerful platform for confining metals at the interface to realize large-area, monolayer-to-few-layer, air-stable metals, metal alloys, and metal compounds. In this review, we discuss the mechanisms governing intercalant-layer formation from both experimental and theoretical perspectives, as well as the characterization techniques used to verify intercalation and resolve interfacial superstructures, including low-energy electron diffraction, scanning tunneling microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, and microscopy methods. Enabled by atomic-scale confinement and the unique asymmetric environment of the host interface, these EG/SiC systems exhibit a range of emergent properties, including metal-to-semiconductor transitions, superconductivity, spin–orbit-related phenomena, and two-dimensional magnetic properties. Finally, recent processing advances toward future device applications and direct epitaxial heterostructures are discussed.