NNN 10 P Ultra-low lattice thermal conductivity of one-dimensional quantum dot Si/Ge superlattices
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NIKA, Denis, ZINCENCO, Nadejda, ISACOVA, Calina, POKATILOV, Evghenii, FOMIN, Vladimir, BALANDIN, Alexander A.. NNN 10 P Ultra-low lattice thermal conductivity of one-dimensional quantum dot Si/Ge superlattices. In: Materials Science and Condensed Matter Physics, 13-17 septembrie 2010, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2010, Editia 5, p. 206.
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Materials Science and Condensed Matter Physics
Editia 5, 2010
Conferința "Materials Science and Condensed Matter Physics"
Chișinău, Moldova, 13-17 septembrie 2010

NNN 10 P Ultra-low lattice thermal conductivity of one-dimensional quantum dot Si/Ge superlattices


Pag. 206-206

Nika Denis12, Zincenco Nadejda1, Isacova Calina1, Pokatilov Evghenii1, Fomin Vladimir3, Balandin Alexander A.2
 
1 Moldova State University,
2 University of California, Riverside,
3 Institute for Integrative Nanosciences
 
Disponibil în IBN: 21 aprilie 2021


Rezumat

The reduction of the phonon thermal conductivity via either phonon-interface scattering or controlled modification of the acoustic phonon dispersion in nanostructures, referred to as phonon engineering [1], was identified as one of the promising strategies for enhancement of the thermoelectric figure of merit ZT. The thermal conductivity of Si nanowires (NWs) is already reduced owing to the phonon – boundary scattering and phonon confinement effects [2, 3]. Here we show theoretically that the phonon thermal conductivity can be suppressed even further in one-dimensional quantum dot superlattices (1D-QDS). The effect is due to the strong localization of the acoustic phonons in such structures (see Fig. 1(a)). The structure acts as a phonon filter removing many phonon modes from thermal transport. Using the approach of Ref. [2-3], we found that the “phonon filtering” leads to a major reduction (by a factor of 5 to 10 for a chosen material system) in the thermal conductivity of 1D-QDS as compared to that of conventional Si NWs (see Fig. 1(b)). We also show how 1D-QDS can be optimized (e.g. by changing superlattice periods or shape of quantum dots) to have a maximum ZT at different temperatures. Our findings are in line with the reduction of the thermal conductivity down to the sub-1 W m-1 K-1 range achieved in multilayered quantum dot arrays [4-5].figureFig. 1: (a) Phonon energy dispersions in Si/Ge 1D-QDS with lateral cross-section 4.88 ´ 4.88 nm2. The energy branches with quantum numbers s = 0-4, 10, 30, 50, ..., 190, 200, 300, ..., 1100, 1120 are shown. (b) The phonon thermal conductivity shown as a function of temperature.