Large enhancement of thermoelectric performance in MoS2/h-BN heterostructure due to vacancy-induced band hybridization-猫眼课题宝

DOI：

10.1073/pnas.2007495117

发表时间：

2020-06

期刊：

Proceedings of the National Academy of Sciences

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

Jing Wu;Jing Wu;Yanpeng Liu;Yanpeng Liu;Yi Liu;Yongqing Cai;Yunshan Zhao;Yunshan Zhao;Hong Kuan Ng;Hong Kuan Ng;Kenji Watanabe;T. Taniguchi;Gang Zhang;Cheng-Wei Qiu;Cheng-Wei Qiu;D. Chi;A. C. Neto;J. Thong;K. Loh;K. Loh;K. Hippalgaonkar;K. Hippalgaonkar;K. Hippalgaonkar

意义2D半导体中相关现象的研究为理解和设计材料功能(如热电)开辟了新的途径，这些功能是在容易接近的范德华固体中实现的。在天然和合成的TMD晶体中不可避免地存在空位等局域结构缺陷，并被预测为能够增强强关联效应的磁性杂质。在这里，我们通过合理地选择h-BN作为衬底，发现了富硫空位MoS_2中的异常热电行为。我们证明了空位诱导的近藤杂化可以很好地控制热电输运性质。在MoS_2/h-BN器件中，热电功率因数显著提高了两个数量级。二维(2D)纳米片中原子空位引起的局域杂质态将对共振散射引起的电荷输运产生深远影响，并可用于控制热电性质。然而，这些杂质的影响往往被外部涨落和涡流层界面所掩盖，因此，从实验上探索空位杂质与热电参数之间的关系是一项具有挑战性的工作。在这项工作中，我们证明了六方氮化硼(h-BN)衬底负载的n型二硫化钼(MoS_2)具有很大的反常正Seebeck系数和强能带杂化。具有50.0±5.0 meV的大电导子带分裂的MoS_2上空位的存在可能有助于近藤绝缘体的性质。此外，通过调节化学势，热电功率因子可以提高两个数量级，达到50 mW m−1 K−2。我们的工作表明，2D材料中的缺陷工程为控制能带结构和调节热电输运提供了一种有效的策略。

Significance The study of correlated phenomena in 2D semiconductors opens up new pathways toward understanding and engineering material functionalities (such as thermoelectrics) in easily accessible van der Waals solids. Local structural defects such as vacancies inevitably exist in natural as well as synthetic TMD crystals and have been predicted to serve as magnetic impurities capable of enhancing the strongly correlated effect. Herein we discover unusual thermoelectric behavior in sulfur vacancy-enriched MoS2 by rationally selecting h-BN as the substrate. We demonstrate that the thermoelectric transport properties can be strongly manipulated by vacancy-induced Kondo hybridization. A significant enhancement of thermoelectric power factor by two orders of magnitude is achieved in the MoS2/h-BN device. Local impurity states arising from atomic vacancies in two-dimensional (2D) nanosheets are predicted to have a profound effect on charge transport due to resonant scattering and can be used to manipulate thermoelectric properties. However, the effects of these impurities are often masked by external fluctuations and turbostratic interfaces; therefore, it is challenging to probe the correlation between vacancy impurities and thermoelectric parameters experimentally. In this work, we demonstrate that n-type molybdenum disulfide (MoS2) supported on hexagonal boron nitride (h-BN) substrate reveals a large anomalous positive Seebeck coefficient with strong band hybridization. The presence of vacancies on MoS2 with a large conduction subband splitting of 50.0 ± 5.0 meV may contribute to Kondo insulator-like properties. Furthermore, by tuning the chemical potential, the thermoelectric power factor can be enhanced by up to two orders of magnitude to 50 mW m−1 K−2. Our work shows that defect engineering in 2D materials provides an effective strategy for controlling band structure and tuning thermoelectric transport.

Large enhancement of thermoelectric performance in MoS2/h-BN heterostructure due to vacancy-induced band hybridization

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