Terahertz emission from ultrathin bismuth layers

Thinner than 10 nm layers of bismuth (Bi) were grown on (111) Si substrates by molecular beam epitaxy. Terahertz (THz) radiation pulses from these layers excited by tunable wavelength femtosecond optical pulses were measured. THz emission sets on when the photon energy exceeds 0.45 eV, which was exp...

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Veröffentlicht in:Optics letters 2021-08, Vol.46 (15), p.3681-3684
Hauptverfasser: Devenson, Jan, Norkus, Ričardas, Juškėnas, Remigijus, Krotkus, Arūnas
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Sprache:eng
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Zusammenfassung:Thinner than 10 nm layers of bismuth (Bi) were grown on (111) Si substrates by molecular beam epitaxy. Terahertz (THz) radiation pulses from these layers excited by tunable wavelength femtosecond optical pulses were measured. THz emission sets on when the photon energy exceeds 0.45 eV, which was explained by the semimetal-to-semiconductor transition at this Bi layer thickness. A THz signal has both isotropic and anisotropic components that could be caused by the lack of balance of lateral photocurrent components and the shift currents, respectively.
ISSN:0146-9592
1539-4794
DOI:10.1364/OL.425271