Tsai Wei-Han, Chen Cheng-Lung, Vankayala Ranganayakulu K, Lo Ying-Hsiang, Hsieh Wen-Pin, Wang Te-Hsien, Huang Ssu-Yen, Chen Yang-Yuan
Department of Physics, National Taiwan University, Taipei 10617, Taiwan.
Institute of Physics, Academia Sinica, Taipei 115, Taiwan.
Nanomaterials (Basel). 2024 Apr 25;14(9):747. doi: 10.3390/nano14090747.
Thermoelectric power can convert heat and electricity directly and reversibly. Low-dimensional thermoelectric materials, particularly thin films, have been considered a breakthrough for separating electronic and thermal transport relationships. In this study, a series of BiSbTe thin films with thicknesses of 0.125, 0.25, 0.5, and 1 μm have been fabricated by RF sputtering for the study of thickness effects on thermoelectric properties. We demonstrated that microstructure (texture) changes highly correlate with the growth thickness in the films, and equilibrium annealing significantly improves the thermoelectric performance, resulting in a remarkable enhancement in the thermoelectric performance. Consequently, the 0.5 μm thin films achieve an exceptional power factor of 18.1 μWcmK at 400 K. Furthermore, we utilize a novel method that involves exfoliating a nanosized film and cutting with a focused ion beam, enabling precise in-plane thermal conductivity measurements through the 3ω method. We obtain the in-plane thermal conductivity as low as 0.3 WmK, leading to a maximum ZT of 1.86, nearing room temperature. Our results provide significant insights into advanced thin-film thermoelectric design and fabrication, boosting high-performance systems.
热电功率可以直接且可逆地转换热和电。低维热电材料，特别是薄膜，被认为是分离电子和热传输关系的一个突破。在本研究中，通过射频溅射制备了一系列厚度分别为0.125、0.25、0.5和1μm的BiSbTe薄膜，以研究厚度对热电性能的影响。我们证明了微观结构（织构）变化与薄膜中的生长厚度高度相关，并且平衡退火显著改善了热电性能，从而使热电性能得到显著增强。因此，0.5μm厚的薄膜在400K时实现了高达18.1μWcmK的优异功率因子。此外，我们采用了一种新颖的方法，即剥离纳米尺寸的薄膜并用聚焦离子束切割，从而能够通过3ω方法精确测量面内热导率。我们获得了低至0.3WmK的面内热导率，导致最大ZT值达到1.86，接近室温。我们的结果为先进薄膜热电设计和制造提供了重要见解，推动了高性能系统的发展。
