Analytical study of the thermoelectric properties in silicene

IF 2.6 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica Scripta Pub Date : 2024-09-12 DOI:10.1088/1402-4896/ad7414

R Amarnath, K S Bhargavi and S S Kubakaddi

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引用次数: 0

Abstract

Theoretically, we investigate the thermoelectric (TE) properties namely, electrical conductivity (σ), diffusion thermopower (Sd), power factor (PF), electronic thermal conductivity (κe) and thermoelectric figure of merit (ZT) for silicene on Al2O3 substrate. TE coefficients are obtained by solving the Boltzmann transport equation taking account of the electron scattering by all the relevant scattering mechanisms in silicene, namely charged impurity (CI), short-range disorder (SD), intra- and inter-valley acoustic (APs) and optical (OPs) phonons, and surface optical phonons (SOPs). The TE properties are numerically studied as a function of temperature T (2–400K) and electron concentration ns(0.1–10 × 1012 cm−2). The calculated σ and Sdare found to be governed by CIs at low temperatures (T< ∼ 10 K), similar to that in graphene. At higher T, they are found to be mainly dominated by the intra- and inter-valley APs. The resultant σ (Sd) is found to decrease (increase) with increasing T, whereas PF remains nearly constant for T> ∼ 100 K. On the other hand, ns dependence shows that σ (Sd) increases (decreases) with increasing ns; with PF relatively constant at lower ns and then decreases with increasing ns. At room temperature, the calculated σ (Sd) in silicene is closer to that in graphene and about an order of magnitude greater (less) than that in monolayer (ML) MoS2. The κe is found to be weakly depending on T and Wiedemann–Franz law is shown to be violated. We have predicted a maximum PF ∼3.5 mW m−1 K−2, at 300 K for ns = 0.1 × 1012 cm−2 from which the estimated ZT = 0.11, taking a theoretically predicted lattice thermal conductivity κl = 9.4 Wm−1 K−1, is a maximum. This ZT is much greater than that of graphene and ML MoS2. The ZT is found to decrease with the increasing ns. The ZT values for other values of ns in silicene, at 300 K, also show much superiority over graphene, thus making silicene a preferred thermoelectric material because of its relatively large σ and very small κl.

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硅的热电特性分析研究

我们从理论上研究了硅烯在 Al2O3 衬底上的热电（TE）特性，即导电率 (σ)、扩散热功率 (Sd)、功率因数 (PF)、电子热导率 (κe)和热电优点系数 (ZT)。TE 系数是通过求解波尔兹曼输运方程得到的，其中考虑了硅烯中所有相关散射机制的电子散射，即带电杂质（CI）、短程无序（SD）、谷内和谷间声子（APs）和光学声子（OPs）以及表面光学声子（SOPs）。数值研究了 TE 特性与温度 T（2-400K）和电子浓度 ns（0.1-10 × 1012 cm-2）的函数关系。计算得出的 σ 和 Sd 在低温（T< ∼ 10 K）下受 CIs 控制，与石墨烯的情况类似。在较高温度下，它们主要由谷内和谷间 AP 主导。另一方面，ns 依赖性表明 σ (Sd) 随着 ns 的增加而增加（减少）；PF 在较低 ns 时相对恒定，然后随着 ns 的增加而减少。在室温下，硅烯的计算σ（Sd）更接近石墨烯的计算σ（Sd），比单层（ML）MoS2 的计算σ（Sd）高（低）一个数量级。我们发现κe 微弱地依赖于 T，并证明违反了 Wiedemann-Franz 定律。我们预测在 ns = 0.1 × 1012 cm-2 时，300 K 的最大 PF ∼3.5 mW m-1 K-2，根据理论预测的晶格热导率 κl = 9.4 Wm-1 K-1，估计 ZT = 0.11。该 ZT 远远大于石墨烯和 ML MoS2 的 ZT。随着 ns 的增大，ZT 值会减小。在 300 K 时，硅烯中其他 ns 值的 ZT 值也比石墨烯高出很多，因此硅烯因其相对较大的 σ 和极小的 κl 而成为首选热电材料。

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来源期刊

Physica Scripta 物理-物理：综合

CiteScore

3.70

自引率

3.40%

发文量

782

审稿时长

4.5 months

期刊介绍： Physica Scripta is an international journal for original research in any branch of experimental and theoretical physics. Articles will be considered in any of the following topics, and interdisciplinary topics involving physics are also welcomed: -Atomic, molecular and optical physics- Plasma physics- Condensed matter physics- Mathematical physics- Astrophysics- High energy physics- Nuclear physics- Nonlinear physics. The journal aims to increase the visibility and accessibility of research to the wider physical sciences community. Articles on topics of broad interest are encouraged and submissions in more specialist fields should endeavour to include reference to the wider context of their research in the introduction.