Phonon-mediated exciton relaxation in two-dimensional semiconductors: selection rules and relaxation pathways
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2021
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| _version_ | 1866917727158927360 |
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| author | Zhang, Xiao-Wei Xie, Kaichen Wang, En-Ge Cao, Ting Li, Xin-Zheng |
| author_facet | Zhang, Xiao-Wei Xie, Kaichen Wang, En-Ge Cao, Ting Li, Xin-Zheng |
| contents | Exciton-phonon coupling (ExPC) is crucial for energy relaxation in semiconductors, yet the first-principles calculation of such coupling remains challenging, especially for low-dimensional systems. Here, an accurate algorithm for calculating ExPC is developed and applied in exciton relaxation problems in monolayer WSe2. Considering the interplay between the exciton wave functions and electron-phonon coupling (EPC) matrix elements, we find that ExPC shows distinct selection rules from the ones of EPC. By employing the Wannier exciton model, we generalize these selection rules, which state that the angular quantum numbers of the exciton must match the winding numbers of the EPC matrix elements for the ExPC to be allowed. To verify our theory and algorithm, we calculate inter-valley exciton relaxation pathways, which agrees well with a recent experiment. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2110_08873 |
| institution | arXiv |
| publishDate | 2021 |
| record_format | arxiv |
| spellingShingle | Phonon-mediated exciton relaxation in two-dimensional semiconductors: selection rules and relaxation pathways Zhang, Xiao-Wei Xie, Kaichen Wang, En-Ge Cao, Ting Li, Xin-Zheng Materials Science Exciton-phonon coupling (ExPC) is crucial for energy relaxation in semiconductors, yet the first-principles calculation of such coupling remains challenging, especially for low-dimensional systems. Here, an accurate algorithm for calculating ExPC is developed and applied in exciton relaxation problems in monolayer WSe2. Considering the interplay between the exciton wave functions and electron-phonon coupling (EPC) matrix elements, we find that ExPC shows distinct selection rules from the ones of EPC. By employing the Wannier exciton model, we generalize these selection rules, which state that the angular quantum numbers of the exciton must match the winding numbers of the EPC matrix elements for the ExPC to be allowed. To verify our theory and algorithm, we calculate inter-valley exciton relaxation pathways, which agrees well with a recent experiment. |
| title | Phonon-mediated exciton relaxation in two-dimensional semiconductors: selection rules and relaxation pathways |
| topic | Materials Science |
| url | https://arxiv.org/abs/2110.08873 |