Application of High-Throughput Seebeck Microprobe Measurements on Thermoelectric Half-Heusler Thin Film Combinatorial Material Libraries.
Application of High-Throughput Seebeck Microprobe Measurements on Thermoelectric Half-Heusler Thin Film Combinatorial Material Libraries.
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DOI：
10.1021/acscombsci.7b00019
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发表时间：
2018-01
影响因子：
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通讯作者：
P. Ziółkowski;Matthias Wambach;A. Ludwig;E. Mueller
中科院分区：
文献类型：
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作者：
P. Ziółkowski;Matthias Wambach;A. Ludwig;E. Mueller
鉴于热电(TE)材料体系的多样性和复杂性，组合材料开发方法在寻找新的有前途的化合物方面应运而生。这种方法的成功与高通量表征方法的可用性和可靠性有关，该方法用于识别组合物扩散库内材料结构和性能之间的相互关系。一个有意义的表征始于确定作为TE材料的主要特征的Seebeck系数。它的测量，以及有希望的材料成分的准确性和可检测性，可能会受到热和电测量条件的强烈影响。这项工作阐明了衬底材料、层厚度和薄膜组成扩展库的空间特性分布的相互关系的影响，并利用电势和塞贝克微探针(PSM)对其进行了实验研究。这项研究还得到了数值评估的补充。用磁控溅射方法在选定的衬底(Si、AlN、Al_2O_3)上沉积了半-Heusler复合体系的材料库。根据有限元模拟，假设薄膜具有均匀的性质，在导热系数较高的衬底上，可以预期检测到的热电势Sm显著降低，从而导致材料热电势的低估在15%到50%之间。导热不良的衬底提供了更好的准确性，热功率低估低于8%，但存在空间分辨率较低的问题。根据有限元模拟，在低导电性基板上局部扫描尖锐的热电势峰与测量的热电势相对于均匀薄膜的额外偏差高达70%，这比本研究在热导率较高的基板上的相应情况高66%。
In view of the variety and complexity of thermoelectric (TE) material systems, combinatorial approaches to materials development come to the fore for identifying new promising compounds. The success of this approach is related to the availability and reliability of high-throughput characterization methods for identifying interrelations between materials structures and properties within the composition spread libraries. A meaningful characterization starts with determination of the Seebeck coefficient as a major feature of TE materials. Its measurement, and hence the accuracy and detectability of promising material compositions, may be strongly affected by thermal and electrical measurement conditions. This work illustrates the interrelated effects of the substrate material, the layer thickness, and spatial property distributions of thin film composition spread libraries, which are studied experimentally by local thermopower scans by means of the Potential and Seebeck Microprobe (PSM). The study is complemented by numerical evaluation. Material libraries of the half-Heusler compound system Ti-Ni-Sn were deposited on selected substrates (Si, AlN, Al2O3) by magnetron sputtering. Assuming homogeneous properties of a film, significant decrease of the detected thermopower Sm can be expected on substrates with higher thermal conductivity, yielding an underestimation of materials thermopower between 15% and 50%, according to FEM (finite element methods) simulations. Thermally poor conducting substrates provide a better accuracy with thermopower underestimates lower than 8%, but suffer from a lower spatial resolution. According to FEM simulations, local scanning of sharp thermopower peaks on lowly conductive substrates is linked to an additional deviation of the measured thermopower of up to 70% compared to homogeneous films, which is 66% higher than for corresponding cases on substrates with higher thermal conductivity of this study.