凯发

Nearly a decade ago, the research community was presented with a unique opportunity to explore a new material system known as graphene. Graphene exhibited phenomenal electronic, chemical, and structural properties that constitutes a new paradigm in materials exploration in which atomic layer control is possible, and even though graphene is considered transformational, it is only the “tip of the iceberg.” Synthesizing and heterogeneously combining atomic layered transition metal dichalcogenides to form van der Waals (vdW) solids, where each layer may be different from the previous, is a powerful way to develop novel nanoscale materials. Furthermore, having the ability to tune the physics and chemistry with atomic-level precision is the foundation for “properties-on-demand”, which can have an enormous impact on current and future technologies.  This talk will elaborate on recent breakthroughs for direct growth of two-dimensional atomic layers on a graphene template, and provide evidence that graphene can be an ideal substrate for building van der Waals solids. We have demonstrated the direct growth of MoS2, WSe2, and hBN on epitaxial graphene to form large area van der Waals heterostructures. We reveal that the properties of the underlying graphene dictate properties of the heterostructures, where strain, wrinkling, and defects on the surface of graphene act as nucleation centers for lateral growth of the overlayer. Additionally, we demonstrate that the direct synthesis of TMDs on epitaxial graphene exhibits atomically sharp interfaces. Finally we demonstrate that the direct growth of MoS2 on epitaxial graphene can lead to a 103 improvement in photo response compared to MoS2 alone.