Liquid metal intercalation of epitaxial graphene: large-area gallenene layer fabrication through gallium self-propagation at ambient conditions

TL;DR

This paper presents a novel ambient-condition method for fabricating large-area gallenene beneath epitaxial graphene via liquid gallium intercalation, enabling controlled wafer-scale heterostructures with potential applications in 2D materials.

Contribution

It introduces a self-propagating, room-temperature process for creating wafer-scale gallenene and heterostructures through liquid gallium intercalation beneath epitaxial graphene.

Findings

Successful fabrication of large-area gallenene at room temperature.

Observation of stepwise self-propagation of gallenene on macroscopic scales.

Analysis of heterostructure interactions via XPS and Raman spectroscopy.

Abstract

We demonstrate the fabrication of an ultra thin gallium film, also known as gallenene, beneath epitaxial graphene on 6H-SiC under ambient conditions triggered by liquid gallium intercalation. Gallenene has been fabricated using the liquid metal intercalation, achieving lateral intercalation and diffusion of Ga atoms at room temperature on square centimeter areas limited only by the graphene samples' size. The stepwise self-propagation of the gallenene film below the epitaxial graphene surface on the macroscopic scale was observed by optical microscopy shortly after the initial processing without further physical or chemical treatment. Directional Ga diffusion of gallenene occurs on SiC terraces since the terrace steps form an energetic barrier (Ehrlich-Schwoebel barrier),retarding the gallenene propagation. The subsequent conversion of the epitaxial graphene into quasi free-standing bilayer graphene (QFBLG) and the graphene-gallenene heterostack interactions have been analyzed by XPS and Raman measurements. The results reveal a novel approach for controlled fabrication of wafer-scale gallenene as well as for two-dimensional heterostructures and stacks based on the interaction between liquid metal and epitaxial graphene. Please note, this work was also titled as Graphene meets gallenene -- A straightforward approach to developing large-area heterostacks by gallium self-propagation https://www.researchgate.net/publication/333451130_Graphene_meets_gallenene_-_A_straightforward_approach_to_developing_large-area_heterostacks_by_gallium_self-propagation