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.

中文翻译：

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研究石墨烯基纳米结构的增强的热电性能†

近来，已经证明石墨烯纳米带（GNR）与石墨烯片相比表现出优异的热电性能。但是，尚未对该增强作用背后的潜在机制进行系统研究，并且仍然存在通过优化其电荷载流子浓度来进一步增强GNR的热电性能的重大机会。在这项工作中，我们使用栅极电压调制基于石墨烯的纳米结构的载流子浓度，并使用玻耳兹曼输运方程研究所得的依赖于载流子浓度的热电参数。我们研究了能量依赖的散射时间的影响，以及基底诱导的载流子波动在优化塞贝克系数和功率因数中的作用。我们的方法预测了不同样品中的散射机理和电荷载流子波动的程度，并解释了GNR样品热电性能的增强。随后，我们提出了一条增强石墨烯基器件热电性能的途径，该方法也可以应用于其他二维材料。