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DS: Fachverband Dünne Schichten

DS 42: Thermoelectric Materials

DS 42.4: Vortrag

Donnerstag, 3. April 2014, 15:45–16:00, CHE 89

Reduction of Thermal Conductivity in Si-Isotope-Multilayers — •Michael Bachmann, Michael Czerner, and Christian Heiliger — I. Physikalisches Institut, Justus Liebig University Giessen, D-35392, Germany

The electronic parameters of Silicon show that Silicon is a promising thermoelectric material. The only drawback of using Silicon as a thermoelectric material is its high lattice thermal conductivity. One idea to reduce the lattice thermal conductivity is the manufacturing of Si-isotope-multilayers. It is expected, that in such structures the phonon-phonon scattering is enhanced due to the mass change at the interfaces between the layers, whereas the electronic transport is unaffected. We present phonon transport calculations based on an atomistic Greens function method [1] for ²⁸Si/²⁹Si and ²⁸Si/³⁰Si isotope-multilayer. These results show that a periodic arrangement of the layer-system cannot decrease the phonon thermal conductivity substantially, whereas a random arrangement of the layer-system can lead to a strong decrease in the phonon conductivity. We also show that small deviations from the periodic arrangement are enough to end up in the random regime.
W. Fisher, T.Mingo, N.Numerical Heat Transfer, Part B: 2007, 51, 333