Studying the intrinsic behavior 2D materials requires attention to both external and internal sources of disorder. This talk will first review the techniques used to create clean heterostructures with hBN to reduce environmental disorder. In graphene, ten years of progress has led to device performance now rivaling he highest-quality GaAs-based heterostructures.  Semiconducting transition metal dichalcogenides (TMDs) also benefit from hBN encapsulation but are limited by atomic defects.  The types and density of atomic defects in TMDs will be reviewed, as well as progress in synthesis of TMDs with dramatically lower defect density.  Combining higher crystal quality and clean encapsulation allows observation of greatly enhanced optical properties, including near-unity photoluminescence quantum yield, and long excited-state lifetime in TMD heterostructures. In addition, electronic transport measurements show improved carrier mobility and reveal many new details of the Landau spectra, including observation of fractional quantum Hall states in monolayer TMDs.  

James Hone is currently Wang Fong-Jen Professor of Mechanical Engineering at Columbia University, and director of PAS3, Columbia’s Materials Science Research and Engineering Center (MRSEC).  He received his BS in physics from Yale in 1990, and PhD in experimental condensed matter physics from UC Berkeley in 1998, and did postdoctoral work at the University of Pennsylvania and Caltech, where he was a Millikan Fellow.  He joined the Columbia faculty in 2003.