论文标题
来自全波段原子模拟的INAS纳米线的热电特性
Thermoelectric properties of InAs nanowires from full-band atomistic simulations
论文作者
论文摘要
在这项工作中，我们从理论上探讨了维数对INAS纳米线的热电功率因子的影响，通过将原子的紧密结合计算与线性化的Boltzmann运输形式主义耦合。我们认为直径从40nm（散装）到3nm（1D）的纳米线，这允许在统一的大型原子化描述中正确探索较大直径范围内统一的大规模原子化描述。我们发现，由于纳米线的直径降低到d <10 nm以下，因此Seebeck系数大大增加，这是强大子带量化的结果。在声子限制的散射条件下，在d = 10 nm左右观察到功率因数的〜6倍大幅提高。计算中表面粗糙度散射的引入将这种功率因数的提高降低到〜2x。随着直径降低至d = 3 nm，功率因数会降低。我们的结果表明，尽管诸如INAS之类的低有效质量材料可以在较大的直径下达到低维行为，并显示出明显的热电功率因数改善，但在较大的直径下，表面粗糙度也更强，这使大多数预期的功率因数优势远离。但是，可以在d = 10 nm左右观察到的功率因数提高，因为洛伦兹的数量和声子导热率都在该直径下降低，因此可以被证明是有益的。因此，通过使用跨越相应长度尺度的大规模全带模拟，这项工作正确阐明了低维材料中功率因数改善（或降解）背后的原因。提出的精心计算方法可以用作为2D和3D材料电子结构开发类似方案的平台。
In this work we theoretically explore the effect of dimensionality on the thermoelectric power factor of InAs nanowires by coupling atomistic tight-binding calculations to the Linearized Boltzmann transport formalism. We consider nanowires with diameters from 40nm (bulk-like) down to 3nm (1D), which allows for the proper exploration of the power factor within a unified large-scale atomistic description across a large diameter range. We find that as the diameter of the nanowires is reduced below d < 10 nm, the Seebeck coefficient increases substantially, a consequence of strong subband quantization. Under phonon-limited scattering conditions, a considerable improvement of ~6x in the power factor is observed around d = 10 nm. The introduction of surface roughness scattering in the calculation reduces this power factor improvement to ~2x. As the diameter is decreased down to d = 3 nm, the power factor is diminished. Our results show that, although low effective mass materials such as InAs can reach low-dimensional behavior at larger diameters and demonstrate significant thermoelectric power factor improvements, surface roughness is also stronger at larger diameters, which takes most of the anticipated power factor advantages away. However, the power factor improvement that can be observed around d = 10 nm, could prove to be beneficial as both the Lorenz number and the phonon thermal conductivity are reduced at that diameter. Thus, this work, by using large-scale full-band simulations that span the corresponding length scales, clarifies properly the reasons behind power factor improvements (or degradations) in low-dimensional materials. The elaborate computational method presented can serve as a platform to develop similar schemes for 2D and 3D material electronic structures.
