2. Articole

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Author: search.filters.author.Fomin, VladimirSubject: search.filters.subject.phonons

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    Phonons and thermal transport in Si/SiO2 multishell nanotubes: Atomistic study [Articol]
    (MDPI, 2021) Isacova, Calina; Cocemasov, Alexandr; Nika, Denis; Fomin, Vladimir
    Thermal transport in the Si/SiO2 multishell nanotubes is investigated theoretically. The phonon energy spectra are obtained using the atomistic lattice dynamics approach. Thermal conduc- tivity is calculated using the Boltzmann transport equation within the relaxation time approximation. Redistribution of the vibrational spectra in multishell nanotubes leads to a decrease of the phonon group velocity and the thermal conductivity as compared to homogeneous Si nanowires. Phonon scattering on the Si/SiO2 interfaces is another key factor of strong reduction of the thermal conduc- tivity in these structures (down to 0.2 Wm−1K−1 at room temperature). We demonstrate that phonon thermal transport in Si/SiO2 nanotubes can be efficiently suppressed by a proper choice of nanotube geometrical parameters: lateral cross section, thickness and number of shells. We argue that such nanotubes have prospective applications in modern electronics, in cases when low heat conduction is required.
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    Resonant terahertz light absorption by virtue of tunable hybrid interface phonon–plasmon modes in semiconductor nanoshellsn [Articol]
    (MDPI, 2019) Nika, Denis; Fomin, Vladimir; Devreese, Josef; Pokatilov, Evghenii; Tempere, Jacques
    Metallic nanoshells have proven to be particularly versatile, with applications in biomedical imaging and surface-enhanced Raman spectroscopy. Here, we theoretically demonstrate that hybrid phonon-plasmon modes in semiconductor nanoshells offer similar advantages in the terahertz regime. We show that, depending on tm,n,nhe doping of the semiconductor shells, terahertz light absorption in these nanostructures can be resonantly enhanced due to the strong coupling between interface plasmons and phonons. A threefold to fourfold increase in the absorption peak intensity was achieved at specific values of electron concentration. Doping, as well as adapting the nanoshell radius, allowed for fine-tuning of the absorption peak frequencies.