Properties of synthetic epitaxial graphene/molybdenum disulfide lateral heterostructures

Graphene has been proposed as a high-quality contact to two-dimensional (2D) transition metal dichalcogenides (TMDs) for the development of “all 2D” devices. Here, we demonstrate the direct-growth of epitaxial graphene (EG) based lateral heterostructures where the EG acts as a directly grown contact to a molybdenum disulfide (MoS2) channel. Utilizing a “seed-free” process, the nucleation of MoS2 occurs at the lateral substrate/graphene interface, and subsequently grows outward from the edge of the graphene. Transmission electron microscopy (TEM) of the heterostructure provides the first direct observation that a pristine vertical overlap of MoS2 on graphene exists, instead of previously reported horizontal stitching, and demonstrates full preservation of the van der Waals gap in the overlap region. Electrolytic gating of the MoS2/EG heterostructures provides evidence that EG can significantly improve transport compared to the traditional metal/MoS2 junctions, reducing contact resistance by > 10x, while reducing the sheet resistance by ∼ 70%.