| Autor: |
Patel, Hiral, Huang, Lujie, Kim, Cheol-Joo, Park, Jiwoong, Graham, Matt W. |
| Rok vydání: |
2018 |
| Předmět: |
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| Zdroj: |
Stacking Angle-Tunable Photoluminescence from Interlayer Exciton States in Twisted Bilayer Graphene, Nature Communications, 10, 1445, 2019, https://www.nature.com/articles/s41467-019-09097-x |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1038/s41467-019-09097-x |
| Popis: |
Using resonant 2-photon excitation of interlayer electrons in twisted bilayer graphene (tBLG), we resolve photoluminescence (PL) that tunes spectrally with stacking angle, {\theta}. This weak signal is 4- 5$\times$ larger than the non-resonant background and is emitted from the interlayer band anti-crossing regions traditionally associated with van Hove singularity resonances. However, our observation of resonant PL emission with delayed ~1 ps electronic thermalization suggests interlayer carriers may instead form bound-excitons. Using both the 2-photon PL and intraband transient absorption spectra, we observe bright and dark state peak-splitting associated with an interlayer exciton binding energy ranging from 0.5 to 0.7 eV for {\theta} = 8$^o$ to 17$^o$. These results support theoretical models showing interlayer excitons in tBLG are stabilized by a vanishing exciton-coupling strength to the metallic continuum states. This unexpected dual metal-exciton optical property of tBLG suggests possible {\theta}-tuneable control over carrier thermalization, extraction and emission in optical graphene-based devices. |
| Databáze: |
arXiv |
| Externí odkaz: |
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