Confinement Epitaxy of Large-Area Two-Dimensional Sn at the Graphene/SiC Interface

TL;DR

This paper demonstrates a method to synthesize large-area, high-quality graphene with intercalated 2D tin beneath it, revealing diffusion-driven growth mechanisms and strain engineering possibilities for advanced quantum materials.

Contribution

It introduces a novel metal intercalation technique using 2D tin to produce high-quality, large-area graphene with tunable properties at the graphene/SiC interface.

Findings

Diffusion-driven intercalation enhances crystalline quality.

Decoupled graphene maintains charge neutrality.

Structural coupling allows strain engineering.

Abstract

Confinement epitaxy beneath graphene stabilizes exotic material phases by restricting vertical growth and altering lateral diffusion, conditions unattainable on bare substrates. However, achieving long-range interfacial order while maintaining high-quality graphene remains a significant challenge. Here, we demonstrate the synthesis of large-area quasi-free-standing monolayer graphene (QFMLG) via the intercalation of a two-dimensional (2D) Sn. While the triangular Sn(1x1) interface exhibits a robust metallic band structure, the decoupled QFMLG maintains charge neutrality, confirmed by photoemission spectroscopy. Using high-resolution Raman spectroscopy and microscopy, we distinguish between direct intercalation and diffusion-driven expansion, identifying the latter as the critical pathway to superior QFMLG crystalline quality. Temperature-dependent analysis reveals dynamical structural coupling between the decoupled QFMLG and the Sn interface, providing a novel degree of freedom for strain engineering. Beyond uncovering the diffusion-driven mechanism, this work establishes metal intercalation as an effective strategy for tailoring durable graphene-metal heterostructures with tunable properties for next-generation quantum materials platforms.