[纳米物理与器件实验室系列学术报告(101)] Atomic and Electronic Structures of 2D electronic materials and their Heterostructures
The emerging atomic layer materials offer a remarkably wide range of building blocks of nanostructures ranging from metals (e.g. graphene), large gap insulators (h-BN), to semiconductors (transition metal dichalcogenides and black phosphorous). Key advantages of these van der Waals materials include a broad span of energy gaps, flexibility of stacking different types of materials to form heterostructures, tunability in material properties by doping and strain, and the relative ease of integration with other electronic and photonic devices. This talk will be focused on our recent work in probing the atomic and electronic structure of transition metal dichalcogenides (TMDs) and their heterostructures, including both vertical and lateral structure.
I will first introduce a comprehensive form of scanning tunneling spectroscopy (STS) which allows us to probe not only the quasi-particle band gaps but also the critical point energy locations and their origins in the Brillouin Zone can be revealed using this comprehensive form of STS. By using this new method, we unravel the systematic trend of the critical point energies for TMDs due to atomic orbital couplings, spin-orbital coupling and the interlayer coupling. By using the vertically stacked MoS2/WSe2, I will show how interlayer coupling can be used as a new designing parameter to create a lateral 2D electronic superlattices. I will then turn attention to WSe2-MoS2 lateral heterostructure where I will show a novel method to probe 2D strain tensor and how the strain changes the band profile as well as the band alignment at the interface.
1. C. D. Zhang et. al.Nano Letters 15, 6494-6500 (2015).
2. C. D. Zhang et. al. Nature Communications 7, 10349 (2016).
3. C. D. Zhang et. al. Science Advances 3, e1601459(2017).
4. C. D. Zhang* et.al. Strain distributions and their influences on electronic structures of WSe2-MoS2 laterally strained heterojunctions, Nature Nanotechnoly in press.
报告人简介：Dr. Chendong Zhang obtained his Ph.D in condensed matter physics from the Institute of Physics, Chinese Academy of Sciences in 2011. From 2011 to 2016, he worked in the University of Texas at Austin as a postdoctoral scholar. He joined the Wuhan University in 2017 as a professor in the School of Physics and Technology. He has specialized in low dimensional quantum materials, scanning tunneling microscopy/spectroscopy and the thin film growth.