Research Seminar - Cosmi Lin

Atomically Precise Material Engineering for Atomically Scaled Electronics

At the atomic scale, new forms of physical phenomena emerge that can provide remarkable opportunities for next-generation tools with unprecedented functionality and energy efficiency. Further down-scaling of electronic devices for the emerging computing systems requires the capability of engineering material properties at the limit of the atomic scale. While scaling of silicon technologies is running out of steam, low-dimensional materials, such as 2D transition-metal dichalcogenides (TMDs) and 1D carbon nanotubes (CNT) or graphene nanoribbons (GNRs) have been envisioned as promising materials for the ultimately scaled transistors and non-classical computing devices. This talk will introduce several recently developed atomically precise material engineering approaches and address some of the key challenges in low-dimensional material electronics.  First, I will present a new reaction pathway to implement the room-temperature atomic-layer substitution for 2D materials. Diverse artificially engineered Janus monolayer materials and their lateral heterostructures can be constructed, which can lead to unique electronic, photonic, and mechanical properties. Second, I will talk about two recent works that addresses the material challenges for forming an energy-barrier-free electrical contacts to 2D semiconductors, including the semimetal contact strategy that eliminates the metal-induced gap states, and the oxygen-incorporated chemical vapor deposition approach that effectively passivates the natural chalcogen vacancies in monolayer TMDs and reduces the defect-induced gap states. Record-high 2D transistor performance is achieved, with the contact resistance on par with silicon technologies, and approaching the quantum limit. Finally, I will introduce our material-level and device-level co-optimization efforts on the bottom-up synthesized GNRs towards the ultimately scaled transistor applications.