Emerging 2D materials, such as atomically thin transition metal dichalcogenides (TMDs) and graphene, have been intensely studied due to their intriguing physical and chemical properties. These properties are usually governed by atomic point defects and interfaces in 2D materials, including edges and domain boundaries. Investigation of the defect and interface structures, therefore, is essential for rational design and optimization of 2D materials. In this talk, I will present our recent scanning tunneling microscopy and spectroscopy studies of atomic point defects and interfaces in 2D TMDs, focusing on those in few-layer PtSe₂ and MoS₂/WS₂ heterostructures. I will further discuss the impacts of external stimuli on defects and interfaces. Particularly, I will show our findings on the shape evolution of monolayer vacancy islands on TiSe₂ surfaces, and the associated growth kinetics, under electrical stressing.

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　　Dr. Chenggang Tao is from the Department of Physics at Virginia Tech. He received his PhD from the University of Maryland under Prof. Ellen Williams, and then worked in Prof. Mike Crommie’s Group at the University of California at Berkeley as a postdoc. Dr. Tao’s current research mainly focuses on emerging 2D materials, energy related materials and surface science, with funding from the US Army Research Office. He has published a number of papers on 2D materials and surface dynamics in leading journals, including Science, Nature Physics, PRL, JACS and Nano Lett.