Computational applications towards 1D van der Waals and phase change materials
Abstract/Contents
- Abstract
- This thesis focuses on the intersection of materials screening, machine learning, and ab-initio calculations, with regards to low dimensional materials - mainly 1D dimensional van der Waals wires and materials with 1D and 2D structures that are particularly suitable for phase change applications. 1D van der Waals materials are a less studied counterpart to their 2D dimensional cousins, but there exists a wide range of such 1D prototypes, including conducting wires that may be suitable as consideration for interconnect replacement candidates. We find exfoliation energies can be reasonable and of the same magnitude as their 2D layers, and evaluate their electronic property changes as we thin these wires to the 1D limit. Due to the fact there is a limited number of such materials, only a few hundred, we machine-learn to expand this composition space, training using the known compositions and using input features based on the elemental-makeup. We particularly target conductive and magnetic materials, as well as those containing transition metals and members of the chalcogen, pnictogen, and halogen families, as those are often particularly suited for chemical vapour decomposition (CVD) and chemical vapour transport (CVT) synthesis mechanisms. Previous work in the group has examined the phase changes in the transition metal dichalcogenides (TMD), and we extend this to a wider range of materials as well as changes where only the relative stacking between low-dimensional components differ. The multiple phases present can display unique dynamics, including switching mechanisms potentially relevant for phase change memory applications. We present a bottom-up screening across all crystalline material to evaluate their phase change potential. For the stacking changes, we study the 1T' and the $T_d$ transition present in select members of the transition metal dichalcogenide family. Past research has focused on the 1T, 1T' and the 2H phase transitions, where the individual 2D layers support differing structures. In contrast, the 1T' and the $T_d$ phases have the same individual layers, but a differing relative orientation that is present between the two. This type of sliding phase transition offers the potential to further reduce switching timescales. We present an analysis on the few-layer behavior of the transition metal dichalcogenide structures of 1T' and T$_d$ WTe$_2$ and MoTe$_2$ with the observation that the energy differences are far more subtle.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2023; ©2023 |
| Publication date | 2023; 2023 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Zhu, Yanbing |
|---|---|
| Degree supervisor | Jornada, Felipe |
| Degree supervisor | Spakowitz, Andrew James |
| Thesis advisor | Jornada, Felipe |
| Thesis advisor | Spakowitz, Andrew James |
| Thesis advisor | Mannix, Andrew J |
| Degree committee member | Mannix, Andrew J |
| Associated with | Stanford University, School of Humanities and Sciences |
| Associated with | Stanford University, Department of Applied Physics |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Yanbing Zhu. |
|---|---|
| Note | Submitted to the Department of Applied Physics. |
| Thesis | Thesis Ph.D. Stanford University 2023. |
| Location | https://purl.stanford.edu/zv082bg3523 |
Access conditions
- Copyright
- © 2023 by Yanbing Zhu
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