Hsiung Te-Chih, Mou Chung-Yu, Lee Ting-Kuo, Chen Yang-Yuan
Department of Physics, National Taiwan University, Taipei 106, Taiwan.
Nanoscale. 2015 Jan 14;7(2):518-23. doi: 10.1039/c4nr05376a.
We report the observation of an order of magnitude enhancement of the thermoelectric figure of merit (ZT = 0.36) in topological insulator Bi1.5Sb0.5Te1.7Se1.3 nanowires at 300 K as compared with the bulk specimen (ZT = 0.028). The enhancement was primarily due to an order of magnitude increase in the electrical conductivity of the surface-dominated transport and thermally activated charge carriers in the nanowires. Magnetoresistance analysis revealed the presence of Dirac electrons and determined that the Fermi level was near the conduction band edge. This may be the first thermoelectric measurement of samples with a chemical potential in the gap of a topological insulator without gate tuning, and provides an opportunity to study the contribution of surface states to the Seebeck coefficient and resistivity without concern for the complex effect of band bending.
我们报告了在300 K时，拓扑绝缘体Bi1.5Sb0.5Te1.7Se1.3纳米线的热电优值（ZT = 0.36）比块状样品（ZT = 0.028）提高了一个数量级的观测结果。这种提高主要是由于纳米线中表面主导输运和热激活载流子的电导率提高了一个数量级。磁阻分析揭示了狄拉克电子的存在，并确定费米能级靠近导带边缘。这可能是首次对化学势处于拓扑绝缘体能隙中且未经栅极调谐的样品进行热电测量，为研究表面态对塞贝克系数和电阻率的贡献提供了机会，而无需考虑能带弯曲的复杂影响。
