Description
- Abstract:
- An appealing approach to manufacturing future generation nanoscale devices envisioned for electronic, magnetic and photonic applications is to exploit the natural tendency of small material clusters to self-organize into well-de?ned patterns. While strain-driven self-assembly is widely viewed as a promising technique for patterning at the nanoscale, to follow this approach and create structures in a desired manner, a reliable means to engineer the characteristic size and shapes that the clusters adopt during self-assembly is essential. Motivated by a signi?cant potential technological impact, a systematic elucidation of how long-range elastic interactions couple with surface and bulk thermodynamics and kinetics to control shape, size and compositional patterns assumes a paramount importance. The work presented here describes a detailed analysis of evolution of morphological and compositional patterns in various strain-driven self-assembled systems. The examples include alloy quantum dots and 2D patterns such as surface stress domains and epitaxial nanowires. Using a combination of experimental, numerical and analytical techniques, it is shown that the elastic strain inherent in these systems leads to dramatic transformations the compositional and morphological patterns that are not predicted by existing theoretical models. Many of these systems can remain trapped in a large variety of long-lived and metastable shapes that arise from an interplay of crystalline anisotropy and relaxation of elastic strain. Based on experimental observations coupled with dynamic growth simulations, we have developed a quantitative understanding of how a self-assembling system falls out of equilibrium. Further, using a combination of ?nite element and optimization methods, a systematic description of the interplay between the composition variations, temperature, strain and the morphology is developed.
- Notes:
- Thesis (Ph.D.) -- Brown University (2008)
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Citation
Medhekar, Nikhil,
"Thermodynamics and kinetics of strain-induced self-assembly on crystal surfaces"
(2008).
Engineering Theses and Dissertations, Mechanics of Solids Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0KP80DN
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Mechanics of Solids Theses and Dissertations
Theses and Dissertations for the Mechanics of Solids department....