Department of Electrical and Electronic Engineering, University of Melbourne, Parkville, 3010, Victoria, Australia.
Nanoscale. 2018 Mar 8;10(10):4786-4792. doi: 10.1039/c8nr00134k.
Recently, it has been demonstrated that graphene nano-ribbons (GNRs) exhibit superior thermoelectric performance compared to graphene sheets. However, the underlying mechanism behind this enhancement has not been systematically investigated and significant opportunity remains for further enhancement of the thermoelectric performance of GNRs by optimizing their charge carrier concentration. In this work, we modulate the carrier concentration of graphene-based nano-structures using a gate voltage and investigate the resulting carrier-concentration-dependent thermoelectric parameters using the Boltzmann transport equations. We investigate the effect of energy dependent scattering time and the role of substrate-induced charge carrier fluctuation in optimizing the Seebeck coefficient and power factor. Our approach predicts the scattering mechanism and the extent of the charge carrier fluctuation in different samples and explains the enhancement of thermoelectric performance of GNR samples. Subsequently, we propose a route towards the enhancement of thermoelectric performance of graphene-based devices which can also be applied to other two-dimensional materials.
最近，已经证明石墨烯纳米带（GNR）的热电性能优于石墨烯片。然而，这种增强背后的机制尚未得到系统的研究，通过优化载流子浓度，GNR 的热电性能仍有很大的提升空间。在这项工作中，我们使用栅极电压来调节基于石墨烯的纳米结构的载流子浓度，并使用玻尔兹曼输运方程研究由此产生的载流子浓度依赖性热电参数。我们研究了能量相关散射时间的影响以及衬底诱导载流子涨落在优化 Seebeck 系数和功率因子方面的作用。我们的方法预测了不同样品中的散射机制和载流子涨落的程度，并解释了 GNR 样品热电性能的增强。随后，我们提出了一种提高基于石墨烯器件的热电性能的方法，该方法也可应用于其他二维材料。
