Reduction of phonon mean free path: From low-temperature physics to room temperature applications in thermoelectricity

Publication date: Available online 23 August 2016 Source:Comptes Rendus Physique Author(s): Olivier Bourgeois, Dimitri Tainoff, Adib Tavakoli, Yanqing Liu, Christophe Blanc, Mustapha Boukhari, André Barski, Emmanuel Hadji It has been proposed for a long time now that the reduction of the thermal conductivity by reducing the phonon mean free path is one of the best way to improve the current performance of thermoelectrics. By measuring the thermal conductance and thermal conductivity of nanowires and thin films, we show different ways of increasing the phonon scattering from low-temperature up to room-temperature experiments. It is shown that playing with the geometry (constriction, periodic structures, nano-inclusions), from the ballistic to the diffusive limit, the phonon thermal transport can be severely altered in single crystalline semiconducting structures; the phonon mean free path is in consequence reduced. The diverse implications on thermoelectric properties will be eventually discussed.

Source: Comptes Rendus Physique - August 22, 2016 Category: Physics Source Type: research