title: Significant reduction of thermal conductivity in silicon nanowire arrays.
abstract: Vertically aligned single-crystal silicon nanowire arrays (SiNWs) with various lengths, surface roughnesses and porosities were fabricated with the metal-assisted chemical etching method. Using the laser flash technique and differential scanning calorimetry, we characterized the thermal conductivities of bulk SiNWs/Si/SiNWs sandwich-structured composites (SSCs) at room temperature (300 K). The results demonstrate that the thermal conductivities of SSCs notably decrease with increases in the length, surface roughness and porosity of SiNWs. Furthermore, based on the series thermal-resistance model, we calculated the thermal conductivity of porous SiNWs to be as low as 1.68 W m(-1) K(-1) at 300 K. Considering the remarkable phonon scattering from the diameter, surface roughness and porosity of SiNWs, leading to a significant reduction of the thermal conductivity, SSCs and SiNWs could be applied to high-performance thermoelectric devices.
authors.affiliation: Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.forename: Shao-long
authors.initials: SL
authors.lastname: Wu
authors.forename: Rui-ting
authors.initials: RT
authors.lastname: Zheng
authors.forename: Guo-an
authors.initials: GA
authors.lastname: Cheng