Poudel Nirakar, Liang Shi-Jun, Choi David, Hou Bingya, Shen Lang, Shi Haotian, Ang Lay Kee, Shi Li, Cronin Stephen
Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, CA, 90089, USA.
Engineering Product Development (EPD), Singapore University of Technology and Design (SUTD), Singapore, 487372, Singapore.
Sci Rep. 2017 Oct 26;7(1):14148. doi: 10.1038/s41598-017-12704-w.
The thermoelectric voltage generated at an atomically abrupt interface has not been studied exclusively because of the lack of established measurement tools and techniques. Atomically thin 2D materials provide an excellent platform for studying the thermoelectric transport at these interfaces. Here, we report a novel technique and device structure to probe the thermoelectric transport across Au/h-BN/graphene heterostructures. An indium tin oxide (ITO) transparent electrical heater is patterned on top of this heterostructure, enabling Raman spectroscopy and thermometry to be obtained from the graphene top electrode in situ under device operating conditions. Here, an AC voltage V(ω) is applied to the ITO heater and the thermoelectric voltage across the Au/h-BN/graphene heterostructure is measured at 2ω using a lock-in amplifier. We report the Seebeck coefficient for our thermoelectric structure to be -215 μV/K. The Au/graphene/h-BN heterostructures enable us to explore thermoelectric and thermal transport on nanometer length scales in a regime of extremely short length scales. The thermoelectric voltage generated at the graphene/h-BN interface is due to thermionic emission rather than bulk diffusive transport. As such, this should be thought of as an interfacial Seebeck coefficient rather than a Seebeck coefficient of the constituent materials.
由于缺乏成熟的测量工具和技术，原子级突变界面处产生的热电压尚未得到专门研究。原子级薄的二维材料为研究这些界面处的热输运提供了一个绝佳的平台。在此，我们报告一种用于探测Au/h-BN/石墨烯异质结构热输运的新技术和器件结构。在该异质结构顶部制作了氧化铟锡（ITO）透明电加热器，使得能够在器件工作条件下原位从石墨烯顶部电极获得拉曼光谱和温度测量结果。在此，向ITO加热器施加交流电压V(ω)，并使用锁相放大器在2ω处测量Au/h-BN/石墨烯异质结构两端的热电压。我们报告我们的热电器件结构的塞贝克系数为-215 μV/K。Au/石墨烯/h-BN异质结构使我们能够在极短长度尺度的范围内探索纳米长度尺度上的热输运和热电输运。在石墨烯/h-BN界面处产生的热电压是由于热电子发射而非体扩散输运。因此，这应被视为界面塞贝克系数而非组成材料的塞贝克系数。
