Atomistic and phase field models of catalyzed nanowire growth
Abstract/Contents
- Abstract
- Nanowires (NWs) are a type of one-dimensional materials that usually hold a high aspect ratio with a well-defined crystalline structure. This special nanostructure makes NWs promising building-blocks for the next-generation electronic and optical devices. Many techniques have been developed for NW synthesis, among which the vapor-liquid-solid (VLS) growth serves as one of the most commonly used methods. However, many fundamental questions regarding its mechanism, such as the nucleation failure and NW kinking, are still not fully understood. Computational modelings and simulations can provide valuable insights into the study of the NW VLS growth mechanism. In this study, for Au-catalyzed Ge crystal growth, a modified embedded atom method (MEAM) potential is developed, which is well fitted to the Au-Ge binary phase diagram. For the Au-Si system, molecular dynamics simulations at various temperatures and Si fractions in liquid are performed to systematically study the Au-catalyzed Si crystal growth. The observed growth velocity's dependence on temperature is found to have a positive correlation with the surface atom activity's temperature dependence, both following the Arrhenius equation. This study also recognizes very different behaviors between the growth on {111} and {110} substrates, which can be explained by the crystallographic-dependent surface properties: the {111} interface is flat and inert, while the {110} interface is rough and the atoms are more active. For continuum scale modeling, a three-dimensional multi-phase field model is developed for NW VLS growth. This model can capture several important geometric features of the wires grown along different orientations, including the NW tapering, liquid-solid interface morphology and NW sidewall faceting. The model demonstrates the natural kinking of the NW in the steady state growth regime, suggesting a clear wire diameter dependence. Additionally, with phase field modeling, the stability of the droplet on top of the NW pedestal is studied, providing explanations for kinking at the NW base. Coupling with elasticity, the phase field model is further applied to nano-mechanics problems, such as the strain-induced NW surface roughening and the nano-fin pattern collapse.
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 | Wang, Yanming |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering. |
| Primary advisor | Cai, Wei |
| Primary advisor | McIntyre, Paul Cameron |
| Thesis advisor | Cai, Wei |
| Thesis advisor | McIntyre, Paul Cameron |
| Thesis advisor | Darve, Eric |
| Thesis advisor | Reed, Evan J |
| Advisor | Darve, Eric |
| Advisor | Reed, Evan J |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Yanming Wang. |
|---|---|
| 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 Yanming Wang
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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