Conţinutul numărului revistei |
Articolul precedent |
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619 0 |
SM ISO690:2012 NEVINSKAS, Ignas, NORKUS, Ricardas, GEIZUTIS, Andrejus, KULYUK, Leonid, MICU, Alexandru, SUSHKEVICH, Konstantin, KROTKUS, Arunas. Terahertz pulse emission from photoexcited bulk crystals of transition metal dichalcogenides. In: Journal of Physics D: Applied Physics, 2021, vol. 54, p. 0. ISSN 0022-3727. DOI: https://doi.org/10.1088/1361-6463/abcc26 |
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Journal of Physics D: Applied Physics | ||||||
Volumul 54 / 2021 / ISSN 0022-3727 /ISSNe 1361-6463 | ||||||
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DOI:https://doi.org/10.1088/1361-6463/abcc26 | ||||||
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Multilayer MoS2, MoSe2, and WSe2 crystals were excited with femtosecond optical pulses of various wavelengths. The emitted terahertz (THz) radiation pulses were found to be the most intense at photon energies coinciding with the direct energy gap at the K points of the Brillouin zone of corresponding materials. It was shown that the transition metal dichalcogenides of different dopant type emit THz pulses of opposite polarity, suggesting that the surface field plays a role in THz emission. Nevertheless, the optical pump-THz probe experiments contradicted THz emission observations, demonstrating a decrease in photoconductivity at higher energy quanta. The proposed THz pulse generation mechanism, therefore, assumes the accumulation of excitonic electric dipoles during optical pulse absorption and a fast build-up of the internal electric field inside the samples. This assumption was supported by double optical pulse investigations. |
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Cuvinte-cheie Crystals, Electric fields, Electromagnetic pulse, laser pulses, layered semiconductors, Molybdenum compounds, Optical multilayers, Optical pumping, Selenium compounds, Sulfur compounds, transition metals, Tungsten compounds, Ultrafast lasers |
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