[18p-E214-1~13] 22.1 Joint Session M "Phonon Engineering"

▲ [18p-E214-9] Thermal Conductivity of Si Thin Film with Nanopillars

〇Xin Huang¹, Ryoto Yanagisawa¹, Daisuke Ohori², Seiji Samukawa^2,3, Masahiro Nomura¹ (1.IIS, The Univ. of Tokyo, 2.IFS, Tohoku Univ., 3.AIMR, Tohoku Univ.)

Keywords:Thermal conduction, Silicon nanopillars, Neutral beam etching

Thermal conduction tuning is indispensable for improving the efficiency of silicon-based thermoelectrics, while nanostructuring has been proved to be a promising route towards this direction. In this work, we fabricated high-density nanopillars with 20 nm in height on 50-nm-thick single crystalline silicon nanobeams and phononic crystals via novel neutral beam etching technology in a damage-less and high-performance manner. We investigated thermal conduction in our samples by means of the μ-TDTR method. At 300 K, nanopillars reduce the thermal conductivity of the underlying silicon hosts by more than 16% due to the stronger phonon surface scattering induced by the pillars. At 4 K, the dominant phonon wavelength increase to the range of 10 to 100 nm, hence long-wavelength phonons may ignore the nanopillars with the diameter of 13 nm and transport specularly. In addition, thermal conduction in silicon hosts can be effectively tuned by attaching additional nanopillars, which makes our work promising and unique for effective silicon thermoelectric applications.