Identifying and Engineering Defects in 2D Semiconductors

This talk will describe ongoing efforts to identify the types and locations of point defects in transition metal dichalcogenide single crystals grown by self-flux and chemical vapor transport techniques. These efforts combine STM imaging, multi-mode AFM imaging (conductive AFM, lateral force microscopy), and elemental analysis of bulk crystals. Imaging is performed on cleaved bulk crystals and exfoliated flakes from one to a few layers thick. In order to unambiguously determine defect locations, we introduce intentional substitutional defects at the metal and chalcogen sites. These studies guide efforts to further purify these materials, leading to improved optical and electronic performance.