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DS: Fachverband Dünne Schichten
DS 12: Thermoelectric and Phase Change Materials
DS 12.5: Vortrag
Montag, 16. März 2020, 17:30–17:45, CHE 91
Phonons and thermal conductivity in Si/SiO2 rolled-up nanostructures — •Igor Bogush1,2 and Vladimir Fomin3,4 — 1Scoala Doctorala de Stiinte Fizice si Ingineresti, Institutul de Cercetare si Inovare, Moldova State University, Chisinau MD-2009, Republic of Moldova — 2Department of Theoretical Physics, Faculty of Physics, Moscow State University, 119899, Moscow, Russia — 3Department of Theoretical Physics, Moldova State University, Chisinau MD-2009, Republic of Moldova — 4Institute for Integrative Nanosciences, Leibniz IFW Dresden, Dresden D-01069, Germany
We have developed a differential-geometry formalism for elastodynamic equations applicable for analytical and numerical simulations of phonons in nanowires with arbitrary cross-section geometry and applied it for rolled-up nanostructures. Phonon spectrum for rolled-up Si/SiO2 bilayer nano-structures with free boundaries is shown to have a similar form as that for unrolled flat nanostructures. Analytical calculations lead to the energy corrections proportional to the ratio of the bilayer width to the structure radius. Geometrical effects for rolled-up structures with small width/radius ratio are neglectable. Therefore realistic rolled-up structures with contacting boundaries can be simulated as flat structures preserving contacting boundary conditions in geometrically non-local sense. Phonon modes are denser for structures with more windings. On this basis we explain the experimentally observed thermal conductivity decrease with increasing number of windings. The present work is supported by the DFG grant no. FO 956/4-1.