ABSTRACT: Scalable and controllable top-down exfoliation processes to obtain 2D materials with sufficient size and high quality are often desired for their mass production and device implementation. I will discuss a few metal-assisted methods to exfoliate from a variety of van der Waals (vdW) single crystals into 2D flakes with controlled thickness and morphology, and achieved high yield, high quality, and macroscopic dimensions. Examples include single-crystal monolayer transition metal dichalcogenides (TMDCs), few-layer hBN flakes with controlled thickness, monolayer with periodic lattice deformation, and monolayer nanoribbons. High-quality and large-area monolayers will allow us to further assemble them into artificial stacks, which has been shown to achieve enhanced responses in second-harmonic and high-harmonic generation. The heterobilayer stacks have been used to reveal light-induced interlayer thermal transfer dynamics in ultrafast electron diffraction experiments. Obtaining macroscopic 2D materials with enhanced yield will not only facilitate the fundamental research, but also take us one step closer to mass production and commercialization of the 2D devices in the future.

Biography:   Fang Liu is an assistant professor in the Department of Chemistry at Stanford University.  Her research is focused on the light induced dynamics of solid low dimensional materials and construction of low dimensional artificial structures.  Prior to her current position, she was a DOE Office of Energy Efficiency and Renewable Energy (EERE) postdoctoral fellow at Columbia University.  She received her Ph.D. in 2015 at University of Pennsylvania. She received her B.S. in chemistry at Peking University in 2010.