Open Access

ARTICLE

Phonon Transport of Rough Si/Ge Superlattice Nanotubes

Yuhang Jing¹, Ming Hu^2,3

1 Department of Astronautical Science and Mechanics, Harbin Institute of Technology, Harbin 150001, China.
2 Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering, RWTH Aachen University, 52064 Aachen, Germany. Author to whom all correspondence should be addressed. E-Mail: hum@ghi.rwth-aachen.de (M.H.)
3 Aachen Institute of Advanced Study in Computational Engineering Science (AICES), RWTH Aachen University, 52062 Aachen, Germany.

Computers, Materials & Continua 2013, 38(1), 43-59. https://doi.org/10.3970/cmc.2013.038.043

Abstract

Nanostructuring of thermoelectric materials bears promise for manipulating physical parameters to improve the energy conversion efficiency of thermoelectrics. In this paper the thermal transport in Si/Ge superlattice nanotubes is investigated by performing nonequilibrium molecular dynamics simulations aiming at realizing low thermal conductivity by surface roughening. Our calculations revealed that the thermal conductivity of Si/Ge superlattice nanotubes depends nonmonotonically on periodic length and increases as the wall thickness increases. However, the thermal conductivity is not sensitive to the inner diameters due to the strong surface scattering at thin wall thickness. In addition, introducing roughness onto the superlattice nanotubes surface can destroy the phonon tunneling in superlattice nanotubes, which results in thermal conductivity even surpassing amorphous limit. Furthermore, a nonmonotonic dependence of the thermal conductivity of rough Si/Ge superlattice nanotubes with thicker wall thickness is found, while for thinner wall the thermal conductivity of rough Si/Ge superlattice nanotubes decreases monotonically with surface roughness increasing. Our results provide guidance for designing high performance thermoelectrics using superlattice nanotube.

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