Enhanced Thermoelectric Performance of Rough Silicon Nanowires.
Enhanced Thermoelectric Performance of Rough Silicon Nanowires.
复制标题
DOI：
10.1002/chin.200814011
复制
发表时间：
2008-04
期刊：
影响因子：
--
通讯作者：
A. Hochbaum;Renkun Chen;R. Delgado;W. Liang;E. Garnett;M. Najarian;A. Majumdar;P. Yang
中科院分区：
文献类型：
--
作者：
A. Hochbaum;Renkun Chen;R. Delgado;W. Liang;E. Garnett;M. Najarian;A. Majumdar;P. Yang
世界上大约90%的电力是由热力发动机产生的，这些发动机使用化石燃料燃烧作为热源，通常以30- 40%的效率运行，因此大约有15太瓦的热量损失到环境中。热电模块可能会将这种低级废热的一部分转化为电能。它们的效率取决于它们的材料组分的热电优值系数ZT，该热电优值系数ZT是塞贝克系数、电阻率、热导率和绝对温度的函数。在过去的五十年里，增加ZT > 1一直是一个挑战，因为ZT的参数通常是相互依赖的。虽然纳米结构热电材料可以增加ZT > 1（参考文献2-4），但是所使用的材料（Bi、Te、Pb、Sb和Ag）和工艺通常不容易缩放到实际有用的尺寸。在这里，我们报告的电化学合成的大面积，晶圆级阵列的粗糙硅纳米线，直径为20-300纳米。这些纳米线具有与掺杂的体硅相同的塞贝克系数和电阻率值，但是直径为约50 nm的纳米线表现出热导率降低100倍，在室温下产生ZT = 0.6。对于这样的纳米线，晶格的热导率的贡献接近硅的非晶极限，这不能用目前的理论来解释。虽然体硅是一种差的热电材料，但通过大大降低热导率而不太影响塞贝克系数和电阻率，硅纳米线阵列显示出作为高性能、可扩展的热电材料的前景。
Approximately 90 per cent of the world's power is generated by heat engines that use fossil fuel combustion as a heat source and typically operate at 30-40 per cent efficiency, such that roughly 15 terawatts of heat is lost to the environment. Thermoelectric modules could potentially convert part of this low-grade waste heat to electricity. Their efficiency depends on the thermoelectric figure of merit ZT of their material components, which is a function of the Seebeck coefficient, electrical resistivity, thermal conductivity and absolute temperature. Over the past five decades it has been challenging to increase ZT > 1, since the parameters of ZT are generally interdependent. While nanostructured thermoelectric materials can increase ZT > 1 (refs 2-4), the materials (Bi, Te, Pb, Sb, and Ag) and processes used are not often easy to scale to practically useful dimensions. Here we report the electrochemical synthesis of large-area, wafer-scale arrays of rough Si nanowires that are 20-300 nm in diameter. These nanowires have Seebeck coefficient and electrical resistivity values that are the same as doped bulk Si, but those with diameters of about 50 nm exhibit 100-fold reduction in thermal conductivity, yielding ZT = 0.6 at room temperature. For such nanowires, the lattice contribution to thermal conductivity approaches the amorphous limit for Si, which cannot be explained by current theories. Although bulk Si is a poor thermoelectric material, by greatly reducing thermal conductivity without much affecting the Seebeck coefficient and electrical resistivity, Si nanowire arrays show promise as high-performance, scalable thermoelectric materials.