[20p-C304-1~15] 22.1 Joint Session M "Phonon Engineering"

▲ [20p-C304-6] Aluminium nanopillars reduce thermal conductivity of silicon nanobeams

〇(P)Roman Anufriev¹, Ryoto Yanagisawa¹, Masahiro Nomura^1,2 (1.The Univ. of Tokyo, 2.JST PRESTO)

Keywords:thermal conductivity, phononic crystal

Reducing the thermal conductivity of a material while maintaining its high electrical conductivity is a classical dilemma of thermoelectrics. For instance, while creating nano-pores in thin membranes reduces the thermal conductivity of the membranes, this also reduces the electrical conductivity, so that the overall enhancement of thermoelectric performance remains moderate. One strategy to overcome this difficulty is to change the exterior rather than the interior of nanostructures.
Here, we measured the in-plane thermal conductivity of silicon nanobeams with arrays of aluminium nanopillars on the surface and found that the pillars reduce the thermal conductivity of the µnanobeams by 20 % at room temperature. We attributed the reduction in thermal conductivity to the diffuse phonon scattering at the pillar/beam interfaces. Our TEM observations confirmed that intermixing of the aluminium and silicon atoms results in the amorphization of the surface underneath the pillars.