title: Extreme low thermal conductivity in nanoscale 3D Si phononic crystal with spherical pores.
abstract: In this work, we propose a nanoscale three-dimensional (3D) Si phononic crystal (PnC) with spherical pores, which can reduce the thermal conductivity of bulk Si by a factor up to 10,000 times at room temperature. Thermal conductivity of Si PnCs depends on the porosity, for example, the thermal conductivity of Si PnCs with porosity 50% is 300 times smaller than that of bulk Si. The phonon participation ratio spectra demonstrate that more phonons are localized as the porosity increases. The thermal conductivity is insensitive to the temperature changes from room temperature to 1100 K. The extreme-low thermal conductivity could lead to a larger value of ZT than unity as the periodic structure affects very little the electric conductivity.
authors.affiliation: Department of Physics and Centre for Computational Science and Engineering, National University of Singapore , Singapore 117542, Republic of Singapore.
authors.forename: Lina
authors.initials: L
authors.lastname: Yang
authors.forename: Nuo
authors.initials: N
authors.lastname: Yang
authors.forename: Baowen
authors.initials: B
authors.lastname: Li
mesh_terms: D004553:Electric Conductivity; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D060739:Phonons; D016062:Porosity; D012825:Silicon / Q000737:chemistry*; D013814:Thermal Conductivity
chemical_list: D012825:Silicon