Ultra-High Vacuum Growth and Characterization of Multi-Layered Materials enables material integration

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Assistant Professor Stephen McDonnell’s research focuses on understanding how 2-D materials, such as the transition metal dichalcogenide family, interface with other materials in electronic devices. Understanding the bonding in interface heterostructures is crucial to enabling the engineering required to integrate materials into nanoelectronic device architectures. In his lab, McDonnell has established a dedicated ultra-high vacuum growth and characterization system that allows him not only to synthesize high purity 2-D semiconductors, but also to investigate the structure, composition, and electronic properties of these materials without any atmospheric exposure. This capability has fostered a number of collaborations at UVA, and is part of the school of Engineering's Multifunctional materials integration (MMI).

McDonnell is working with Associate Professor Patrick Hopkins to understand the correlation between metal-semiconductor interface chemistry and both electron and phonon transport across these interfaces. They have found that interface chemistry can have a dramatic effect on thermal transport. The ability to investigate interfaces and also to synthesize 2-D materials has led to a new collaboration with Assistant Professor Mona Zebarjadi. Theoretical models suggest that 2-D materials may enable a new generation of thermoelectric devices. McDonnell has also been collaborating with Professor Giovanni Zangari to investigate the surface chemistry evolution during photoelectrochemical water splitting. Their work has included the integration of graphene as a barrier layer to protect cost-effective silicon photoanodes during operation.