MSE Seminar: Functional Materials through Surface and Interface Engineering
Join MSE for light refreshments and a discussion on materials related to surface and interface structure and metastability.
Gibbsian thermodynamics is pegged on the notion of equilibrium, but, not all equilibria states are equally – some are ‘more equal than others’. A droplet on a poorly wetting surface exemplifies these inequalities in that; evaporation, imbibition, and internal flux renders an apparent sessile state chaotic. Metastable equilibria states are prevalent in nature especially across surfaces and interfaces, and exist in forms of functional concentration gradients (e.g. synaptic cleft), as self-organized surface-adsorbed contaminants (e.g. adventitious water), among many others. This talk presents our efforts to design new technologies and processes based on an understanding of surface and interface structure and metastability. First, a modified emulsification technique was used to quantitatively prepare undercooled metal which led to ambient fabrication of metallic structures and heat-free solder. Second, self-assembled adventitious contaminants were tuned to allow for control step-growth gel formation leading to amphi-phobic surfaces. Finally, bombardment of metallic thin films with atoms leads to asymmetric stress and defect (dislocation) density necessitating remote surface reconstruction. This defect driven process allows for high precision tuning of surface roughness, which in turn leads to new capabilities in device fabrication. This effort led to an understanding of the effect of sub-nanometer roughness on structure of self-assembled monolayers and coherent through-bond charge tunneling. Overall, a balance between structure and metastability can be exploited to design efficient material processing techniques or enable unprecedented technology design.