A master thesis from Aalborg University
Spontaneous Emission in TMDs: Exciton Dispersion, Lifetimes and Purcell Factor
Author(s)
Term
4. term (FYS10)
Education
Publication year
2020
Submitted on
2020-06-03
Pages
88 pages
Abstract
Based on DFT-calculations performed using GPAW, the excitonic, optical, and radiative properties of molybdenym- and tungsten-based TMDs have been examined in detail by use of the Bethe-Salpeter equation in a plane-wave basis with a Keldysh potential. In particular, the sheet conductivity and absorbance have been modelled as well as the radiative lifetime of bright excitonic states. The excitonic lifetimes are based on center-of-mass momenta dispersions in the optical regime, which are found by first using an interpolation scheme on high density DFT calculations and then iteratively computing the BSE. Moreover, the Purcell enhancement of the lifetime in a simple dielectric geometry, as well as a slightly more complicated optical cavity has been examined. Finally, the modelled data has been compared to PL and absorption measurements and other theoretical data, which shows decent agreement.
Based on DFT-calculations performed using GPAW, the excitonic, optical, and radiative properties of molybdenym- and tungsten-based TMDs have been examined in detail by use of the Bethe-Salpeter equation in a plane-wave basis with a Keldysh potential. In particular, the sheet conductivity and absorbance have been modelled as well as the radiative lifetime of bright excitonic states. The excitonic lifetimes are based on center-of-mass momenta dispersions in the optical regime, which are found by first using an interpolation scheme on high density DFT calculations and then iteratively computing the BSE. Moreover, the Purcell enhancement of the lifetime in a simple dielectric geometry, as well as a slightly more complicated optical cavity has been examined. Finally, the modelled data has been compared to PL and absorption measurements and other theoretical data, which shows decent agreement.
Keywords
Emission ; TMDs ; Excitons ; BSE ; Bethe-Salpeter ; Purcell ; Purcell Factor ; GPAW ; Lifetimes ; Green's Functions ; DFT ; QFT
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