Effects of nanoscale porosity on thermoelectric properties of SiGe
Effects of nanoscale porosity on thermoelectric properties of SiGe
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DOI：
10.1063/1.3388076
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发表时间：
2010-05-01
影响因子：
3.2
通讯作者：
Chen, Gang
中科院分区：
文献类型：
--
作者：
Lee, Hohyun;Vashaee, Daryoosh;Chen, Gang
纳米颗粒材料的高热电优值最近取得的成就归功于固结过程的成功优化。尽管热导率降低，但实验观察到，由于电导率的显著降低，多孔纳米颗粒材料的热电优值比块体材料低。为了预测和解释多孔性纳米颗粒材料的热电性质，本文模拟了纳米孔隙率对电子和声子输运的影响。孔洞处的电子散射用量子力学处理，而声子传输用经典图像处理。模拟结果表明，由于纳米颗粒材料中的散射位点数密度较高，载流子在纳米颗粒材料中的分散比在宏观尺度的多孔材料中更为严重。多孔纳米颗粒材料由于具有能量过滤效应和较低的导热系数，提高了Seebeck系数，有利于热电材料的应用。然而，这种优势还不足以克服电导率的缺陷，因此对于纳米晶SiGe来说，高样品密度是必要的。(C)2010年美国物理研究所。[DOI：10.1063/1.3388076]
The recent achievement of the high thermoelectric figure of merit in nanograined materials is attributed to the successful optimization of the consolidation process. Despite a thermal conductivity reduction, it has been experimentally observed that the porous nanograined materials have lower thermoelectric figure of merit than their bulk counterpart due to significant reduction in the electrical conductivity. In this paper, nanoscale porosity effects on electron and phonon transport are modeled to predict and explain thermoelectric properties in porous nanograined materials. Electron scattering at the pores is treated quantum mechanically while phonon transport is treated using a classical picture. The modeling results show that the charge carriers are scattered more severely in nanograined materials than the macroscale porous materials, due to a higher number density of scattering sites. Porous nanograined materials have enhanced Seebeck coefficient due to energy filtering effect and low thermal conductivity, which are favorable for thermoelectric applications. However, the benefit is not large enough to overcome the deficit in the electrical conductivity, so that a high sample density is necessary for nanograined SiGe. (C) 2010 American Institute of Physics. [doi:10.1063/1.3388076]