2019 Fiscal Year Final Research Report
Theoretical study on optical responses of excitons in monolayer transition-metal dichalcogenides
| Project/Area Number |
16K05391
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Condensed matter physics I
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Keywords | 励起子 / 遮蔽効果 / 光学応答 / 層状物質 |
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| Outline of Final Research Achievements |
Optical excitation in semiconductors generates electrons and holes and the Coulomb attraction causes formation of the electron-hole bound state what we call exciton. In a monolayer transition-metal dichalcogenide, the exciton plays a dominant role in its optical response because there is no dielectric environment giving rise to screening outside the two-dimensional electronic system. In this study, we have developed a theoretical method to evaluate the dynamical screening effect for excitons. We calculated exciton absorption spectra under several types of dielectric material such as organic solvents and compound semiconductor substrates and discussed the control of optical responses.
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| Free Research Field |
物性理論
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| Academic Significance and Societal Importance of the Research Achievements |
半導体中の励起子形成に対する動的遮蔽効果は光学応答に影響を及ぼす重要な問題と古くから認識されていたが，非線形固有値問題に帰着され十分な解析がなされていなかった．本研究では，励起子の固有状態を求めることなく，応答関数を直接計算することにより動的遮蔽を考慮した束縛エネルギーを評価する手法を開発し，層状物質の外部環境を制御することで光学応答の変調が可能であることを示した．動作波長の可変性を実現することで光学デバイスへの応用が広がると期待される．
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