Thermomechanical degradation and failure mechanisms in thin film technologies
Abstract/Contents
- Abstract
- From photovoltaics to MEMS, modern technological advancement has increasingly been achieved via complex and multilayered thin film technologies. While thin film applications of materials enable high performance, they also introduce heterogeneities and interfaces which potentially lead to degradation and failure. In this work, I explore the mechanical and fracture properties of a diverse range of inorganic thin film materials, focusing in particular on brittle materials. Fragility of specimens presents an interesting challenge, as it precludes the use of more traditional testing methods, leading to development of new testing metrologies. Multijunction photovoltaics present one such challenge, possessing many internal interfaces of interest which have previously been uncharacterized due to substrate fragility. Photovoltaics need to maintain operational lifetimes in excess of 25 years in order to be economically competitive, and are subjected to a variety of stressing factors, from thermal cycling to moisture ingress, necessitating characterization and understanding of any potential degradation and failure modes. Additionally, accelerated testing methods are integral in order to develop and iterate new materials over shorter timescales. I therefore make use of elevated humidity exposures to explore the moisture-enabled degradation of antireflective coatings, as well as accelerated thermal cycling to characterize the evolution of stress and defects in metal gridlines. The first ever measurements of adhesion in these systems are made through the use of the newly developed composite dual cantilever beam test, which can also be broadly applied to any system that makes use of thin, brittle, or otherwise fragile substrates. In addition, I discuss the mechanical properties of silicon carbide thin film membranes, grown epitaxially upon silicon substrates. These films presently attract enormous interest as they enable fabrication of transducers with exceptional mechanical properties while also making use of well-established silicon micromachining techniques. The residual stresses developed during growth, as well as stresses developed during pressurization and fracture of these membranes are discussed, leading ultimately to better understanding of how these membranes might be used.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Brock, Ryan Elliott |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering. |
| Primary advisor | Dauskardt, R. H. (Reinhold H.) |
| Thesis advisor | Dauskardt, R. H. (Reinhold H.) |
| Thesis advisor | Cai, Wei |
| Thesis advisor | Harris, J. S. (James Stewart), 1942- |
| Advisor | Cai, Wei |
| Advisor | Harris, J. S. (James Stewart), 1942- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Ryan Elliott Brock. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Ryan Elliott Brock
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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