A comparison study on the electronic structures, lattice dynamics and thermoelectric properties of bulk silicon and silicon nanotubes

作者：Lu Peng-Xian^*; Qu Ling-Bo; Cheng Qiao-Huan

来源：Chinese Physics B, 2013, 22(11): 117101.

DOI：10.1088/1674-1056/22/11/117101

• electronic structure
• lattice dynamics
• thermoelectric properties
• silicon nanotube

In order to investigate the mechanism of the electron and phonon transport in a silicon nanotube (SiNT), the electronic structures, the lattice dynamics, and the thermoelectric properties of bulk silicon (bulk Si) and a SiNT have been calculated in this work using density functional theory and Boltzmann transport theory. Our results suggest that the thermal conductivity of a SiNT is reduced by a factor of 1, while its electrical conductivity is improved significantly, although the Seebeck coefficient is increased slightly as compared to those of the bulk Si. As a consequence, the figure of merit (ZT) of a SiNT at 1200 K is enhanced by 12 times from 0.08 for bulk Si to 1.10. The large enhancement in electrical conductivity originates from the largely increased density of states at the Fermi energy level and the obviously narrowed band gap. The significant reduction in thermal conductivity is ascribed to the remarkably suppressed phonon thermal conductivity caused by a weakened covalent bonding, a decreased phonon density of states, a reduced phonon vibration frequency, as well as a shortened mean free path of phonons. The other factors influencing the thermoelectric properties have also been studied from the perspective of electronic structures and lattice dynamics.

• 出版日期2013-11
• 单位郑州大学; 河南工业大学