Electronic Hybridization of Large-Area Stacked Graphene Films

TL;DR

This paper reports on the fabrication and characterization of large-area coupled bilayer graphene films, demonstrating tunable electronic interactions influenced by twist angle and reversible interlayer coupling for potential large-scale applications.

Contribution

It introduces a method to create large-area bilayer graphene with controllable electronic coupling and reversible interlayer interactions, advancing 2D material engineering.

Findings

Large-area bilayer graphene can be fabricated with controlled twist angles.

Interlayer coupling affects optical properties and can be reversibly turned off.

Clean interfaces are maintained over large areas, enabling scalable applications.

Abstract

Direct, tunable coupling between individually assembled graphene layers is a next step towards designer two-dimensional (2D) crystal systems, with relevance for fundamental studies and technological applications. Here we describe the fabrication and characterization of large-area (> cm^2), coupled bilayer graphene on SiO2/Si substrates. Stacking two graphene films leads to direct electronic interactions between layers, where the resulting film properties are determined by the local twist angle. Polycrystalline bilayer films have a "stained-glass window" appearance explained by the emergence of a narrow absorption band in the visible spectrum that depends on twist angle. Direct measurement of layer orientation via electron diffraction, together with Raman and optical spectroscopy, confirms the persistence of clean interfaces over large areas. Finally, we demonstrate that interlayer coupling can be reversibly turned off through chemical modification, enabling optical-based chemical detection schemes. Together, these results suggest that individual 2D crystals can be individually assembled to form electronically coupled systems suitable for large-scale applications.