【摘要】 热电材料是一种能够实现热能与电能直接转换的功能材料，由于无法有效降低块体热电材料的热导率，其性能研究进展缓慢。自上世纪90年代初Hicks等提出了低维化能够显著提高热电材料性能的理论后，薄膜热电材料开始受到广泛关注。低维化提高材料性能的原因主要是材料在低维化后能够产生量子限制效应，使得电子在被压缩维度的运动受到限制。首先，在费米能级附近，与Seebeck系数呈正相关的电子态密度会增大，导致低维热电材料的Seebeck系数相比块体材料显著增大。其次，与块体材料相比，薄膜材料存在更多能够散射声子的晶界，能有效降低晶格热导率。在这两种效应的共同作用下，材料的热电优值（ZT值）能够显著增大。低维热电材料的研究初期主要是通过数学模型和数值计算，从理论上证明量子效应会影响材料的Seebeck系数和电导率，且能实现二者的独立控制，从而提高材料的ZT值。后期的实验数据证明，通过合适的热处理工艺能够有效降低薄膜材料的缺陷，提高其综合性能。因此，热处理工艺的改进对性能的提升也非常重要。热电材料性能的提升离不开制备工艺的进步。为了获得低维化的热电材料，多种薄膜材料制备工艺被用于样品的制备，且不同的制备工艺各有优缺点。Bi-Te基合金不仅可用于低温发电还可用于低温制冷，是目前应用最广泛的低温热电材料，虽然其块体状态下的热电性能研究已趋于完善，但其薄膜状态下热电性能的理论研究还相差甚远，因此Bi-Te基低温薄膜热电材料成为研究热点。本文介绍了国内外采用不同制备工艺生长Bi-Te基热电薄膜材料的发展状况以及热电性能测试方法，提出了在目前发展薄膜热电材料时需要重点关注的方面，并对低维热电材料的发展方向进行了阐述。更多还原

【Abstract】 Thermoelectric materials(TEs) are a kind of functional material which can realize the direct conversion between thermal energy and electricenergy. It is hard for bulk thermoelectric materials to improve the properties because the thermal conductivity of them cannot be reducede ffectively. In the early 1990 s, Hicks and other researchers put forward the theory that low-dimensionalization could greatly improve the performance of TEs, and then the research of thermoelectric thin films has been widely concerned． The reason for low-dimensional materials having higher performance is that they can produce quantum confinement effect, which limits the motion of electrons in the compressed dimension. Firstly, the electron density of states with a positive correlation to Seebeck coefficient increases in the vicinity of the Fermi level, and thus the Seebeck coefficient of the low-dimensional thermoelectric materials increases significantly, compared with the bulk materials. Secondly, thin film materials have more grain boundaries that can scatter the phonon, which will reduce the lattice thermal conductivity effectively. As a result, the thermoelectric figure of merit(ZT value) of the film materials can be improved remarkably through the combined action of the two effects． At the beginning of the research on low-dimensional thermoelectric materials, it is proved that quantum effect can influence Seebeck coefficient and conductivity of the materials, which can control them independently to improve the ZT value of the materials through mathematical modeling and calculation. The later experiments confirm that the proper heat treatment process of thin films can reduce the defects effectively and improve the comprehensive properties. Therefore, the heat treatment and preparation process of thin films are very important to improve the performance of TEs. In order to obtain low-dimensional TEs, thin film materials preparation methods have been applied and have their own advantages and disadvantages. Bi-Te based TEs have become the most widely used low temperature thermoelectric materials at present because it can be not only applied in low temperature power generation but also in low temperature cooling. Although the properties in the bulk state have been improved, the theoretical research of thermoelectric properties in the thin film state is not enough. As a result, Bi-Te based TEs have become a hot spot in the research of low temperature thin film thermoelectric materials． In this paper, the methods for thermoelectric properties measurement and the development of different preparation processes of Bi-Te based thermoelectric thin films at home and abroad are introduced. The research aspects which need to be focused on the development of thin film materials are put forward, and the development direction of low-dimensional TEs is also described.更多还原