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中国物理学会期刊

低维纳米材料热电性能测试方法研究

CSTR: 32037.14.aps.70.20201175

Methodology of teasting thermoelectric properties of low-dimensional nanomaterials

CSTR: 32037.14.aps.70.20201175
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  • 通过近几十年的研究, 人们对于块体及薄膜材料的热电性能已经有了较全面的认识, 热电优值ZT的提高取得了飞速的进展, 比如碲化铋相关材料、硒化亚铜相关材料、硒化锡相关材料的最大ZT值都突破了2. 但是, 这些体材料的热电优值距离大规模实用仍然有较大的差距. 通过理论计算得知, 当块体热电材料被制作成低维纳米结构材料时, 比如二维纳米薄膜、一维纳米线, 热电性能会得到显著的改善, 具有微纳米结构材料的热电性能研究引起了科研人员的极大兴趣. 当块体硅被制作成硅纳米线时, 热电优值改善了将近100倍. 然而, 微纳米材料的热电参数测量极具挑战, 因为块体材料的热电参数测量方法和测试平台已经不再适用于低维材料, 需要开发出新的测量方法和测试平台用来研究低维材料的热导率、电导率和塞贝克系数. 本文综述了几种用于精确测量微纳米材料热电参数的微机电结构, 包括双悬空岛、单悬空岛、悬空四探针结构, 详细介绍了每一种微机电结构的制备方法、测量原理以及对微纳米材料热电性能测试表征的实例.

     

    Through the research in recent decades, one has a comprehensive understanding of the thermoelectric properties of bulk and thin film materials, and made rapid progress of improving the thermoelectric figure of merit ZT, for instance, the maximum ZT values of bismuth telluride related materials, cuprous selenide related materials and tin selenide related materials all exceed 2. However, these bulk materials are still far from the requirements for their practical applications on a large scale. The theoretical calculations show that when bulk thermoelectric materials are made a low-dimensional nanostructured materials, such as two-dimensional nano-films and one-dimensional nanowires, their thermoelectric properties will be significantly improved. Taking silicon for example, when the bulk silicon is made silicon nanowires, the ZT value increases nearly a hundredfold. Hence, researches of the thermoelectric performances of materials with micro-nano structures have received great attention. However, the measurement of thermoelectric parameters of low-dimensional materials has brought challenges to researchers, for the traditional measurement methods or test platforms designed for bulk materials are no longer suitable for measuring thermoelectric parameters (thermal conductivity, electrical conductivity and Seebeck coefficient) of low-dimensional materials. Therefore, new measurement methods and test platforms need developing. In this case, micro-electromechanical system micro-suspended structure came into being. In this approach used are the separated samples and substrates, and isolated heat transfer channels, with which the thermal parameters of micro/nano materials can be accurately measured, and the sensitivity of thermal conductance can reach 10 PW/K. In this review, the structures of several micro-electromechanical systems used to measure the thermoelectric properties of low-dimensional nanostructures are introduced, including double suspended islands, single suspended islands and suspended four-probe structures. Meanwhile, the fabrication methods and measurement principles of these MEMS structures and thermoelectric properties of micro-nano structure materials are described in detail.

     

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