The Library
Large-scale computational simulation and theoretical spectroscopy of 2D metal chalcogenides
Tools
Mean Loh, Siow (2021) Large-scale computational simulation and theoretical spectroscopy of 2D metal chalcogenides. PhD thesis, University of Warwick.
|
PDF
WRAP_Theses_Mean_Loh_2021.pdf - Submitted Version - Requires a PDF viewer. Download (73Mb) | Preview |
Official URL: http://webcat.warwick.ac.uk/record=b3736671~S15
Abstract
The effects of alloying and twisting on the atomic and electronic structures of two-dimensional metal chalcogenides which are current interests of scientific community have been studied in this thesis. Monte Carlo simulations and statistical analysis of the atomic configurations of the as-grown crystal of Mo1−xWxS2 monolayers synthesised by our experimental collaborators both consistently suggest a random distribution. The results calculated by using the ONETEP linear-scaling density functional theory package and the angle-resolved photoemission spectroscopy measurements give consistent results for the bandwidth and the band splitting due to spin-orbit coupling near the topmost valence band at K. The spin-valley locking is proved to be maintained at x = 0.5 through polarisation-resolved photoluminence measurements. In contrast, a striking dopant distribution with striped pattern was observed in the as-grown crystal of W1−xNbxS2 monolayer synthesised by our experimental collaborators, different from the random distribution of Mo1−xWxS2 monolayer. Through the analysis of the binding energy of various dopant distributions, the kinetic processes and the energetics both play roles in forming this kind of dopant distribution. A highly anisotropic conductivity is predicted by our calculations in this alloy. The twistronics in InSe is discussed in the final part of the thesis. We show that the calculations on the InSe bilayer within the primitive cell
can be used to efficiently obtain the topmost valence band of twisted InSe bilayer. The effective mass for holes remains approximately a constant as twist angle varies. It is estimated to be _ 441.1 meV and _ 183.2 meV for A1s intralayer and interlayer exciton binding energies in twisted InSe bilayer regardless of the twist angle. The encapsulated hBN layer in the twisted InSe bilayer is regarded as a spacer to weaken the interaction between two InSe layers. The band structure of the hBN-spaced system can also be well-described by InSe monolayer within the primitive cell calculation. The A1s intralayer exciton binding energy of this system is calculated to be 232.9 meV by using the effective mass for holes of InSe monolayer.
Item Type: | Thesis (PhD) | ||||
---|---|---|---|---|---|
Subjects: | Q Science > QC Physics Q Science > QD Chemistry |
||||
Library of Congress Subject Headings (LCSH): | Chalcogenides -- Electric properties, Chalcogenides -- Structure, Transition metals, Spectrum analysis, Monte Carlo method | ||||
Official Date: | June 2021 | ||||
Dates: |
|
||||
Institution: | University of Warwick | ||||
Theses Department: | Department of Physics | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Hine, Nicholas | ||||
Sponsors: | University of Warwick. Chancellor's International Scholarship | ||||
Extent: | xxi, 146 leaves : illustrations, charts | ||||
Language: | eng |
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |
Downloads
Downloads per month over past year