Effects of Crystalline Anisotropy on Solid-state Dewetting
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letoile-mletoile-phd-dmse-2022-thesis.pdf
Description
Thesis PDF
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52.6 MB
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Author(s)
L'Etoile, Maxwell A.
Advisor(s)
Thompson, Carl V.
Carter, W. Craig
Date Issued
May 2022
Publisher
Massachusetts Institute of Technology
Abstract
Solid-state dewetting is the process by which micro– and nano–scale films, wires, and other fabricated structures on a substrate evolve toward geometries which reduce the overall surface free energy of the system. This process, also sometimes referred to as agglomeration, occurs at elevated temperatures and is mediated by surface selfdiffusion. Regardless of initial conditions, dewetting eventually leads to the formation of one or more particles whose morphology is determined by the orientational dependence of the constituent material’s surface free energy density.
Subtle differences in initial conditions can determine whether a system dewets into a single particle or many and whether this evolution occurs over the course of minutes, hours, days, or years. Furthermore, the intermediate stages of dewetting behavior can exhibit profound complexity, and many materials systems are prone to a host of morphological instabilities. Although decades of research have steadily increased the extent of our knowledge about solid-state dewetting, a generalizable, predictive understanding of dewetting behavior has remained elusive, in large part because of the difficulty of modeling systems with strong crystalline anisotropy.
The work in this thesis focuses on advancing our understanding of the dewetting behavior of single-crystal materials and consists chiefly of two parallel thrusts: the development of a powerful new method for simulating solid-state dewetting and the use of lithographic patterning to experimentally study dewetting in systems with precisely controlled geometries. We apply these two synergistic approaches to understanding the morphological stability of ruthenium nanowires, the effects of ambient conditions on dewetting nickel (110) films, and the dendritic morphologies which arise at the corners of holes in dewetting films.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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