Unveiling the Electronic Properties and Growth Mechanisms of 2D Layered Materials on Au Foils through Scanning Tunneling Microcopy/Spectroscopy Studies

Abstract

2D van der Waals layered materials, represented by transition metal dichalcogenides (TMDCs), graphene, and h-BN, have garnered worldwide research interests due to their unique structures and fascinating physical properties distinct from their bulk counterparts. Featuring superior controllability and scalability, bottom-up synthetic approaches, including chemical vapor deposition, molecular beam epitaxy, etc., are widely adopted for preparing high-quality 2D materials and their heterostructures. In these efforts, Au foils are utilized as favorable substrates due to their chemical inertness, strong interfacial interactions that facilitate epitaxial growth of adlayers, and conductive nature that enables in situ characterizations. Herein, this review summarizes the recent advances in the bottom-up syntheses of 2D materials on Au foils, including the epitaxial growth of single-crystal TMDCs monolayers, the construction of 2D vertical heterostructures, and the preparation of 2D materials with novel phases/structures. Meanwhile, this article also reviews the in situ scanning tunneling microscopy/spectroscopy characterizations of the growth systems, with particular emphasis on unveiling the epitaxy mechanisms of layered single crystals, the stacking configurations of heterostructures, and their intriguing electronic properties. Finally, future opportunities are prospected from the viewpoints of novel phase/structure design, clean transfer, and property explorations of 2D materials on Au substrates.