Uncovering the Deformations in Two-Dimensional Lateral Heterojunctions

Summary form only given, as follows. The complete presentation was not made available for publication as part of the conference proceedings. Two-dimensional (2D) materials have shown great promise in next-generation devices due to their broad electronic and optical properties, while being atomically thin. In order to realize these post-silicon electronics, it will be necessary to electrically connect these 2D materials both in- and out-of- plane. However, the lattice mismatch between these atomic membranes leads to unavoidable strain, dislocations, or ripples, which can strongly affect the mechanical, electronic, and optical properties. Transmission electron microscopy (TEM) and its related techniques have become indispensable tools in uncovering the structure and subsequent physical properties in these 2D materials, atom-by- atom. This presentation will discuss using state-of-the-art TEM techniques to address how different 2D materials merge to form lateral heterostructures, specifically between two distinct transition metal dichalcogenides (TMDs). We discovered how embedded, nanometer channels of one TMD can grow from the lateral heterojunction interface. We also revealed the mechanism of strain relaxation in these two-dimensional heterostructures, and how strain engineering can create heterostructures with tunable optical properties. Our developments have enabled discoveries of the intricate and complex interactions unique to 2D materials. Subsequent control or engineer of these deformations can profoundly impact future material and device development.