Maeda Shintaro, Ishiyama Takamitsu, Nishida Takeshi, Ozawa Tomoki, Saitoh Noriyuki, Yoshizawa Noriko, Suemasu Takashi, Toko Kaoru
Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki305-8573, Japan.
Electron Microscope Facility, TIA, AIST, 1-2-1 Namiki, Tsukuba, Ibaraki305-8564, Japan.
ACS Appl Mater Interfaces. 2022 Dec 14;14(49):54848-54854. doi: 10.1021/acsami.2c14785. Epub 2022 Nov 30.
Group IV materials are promising candidates for highly reliable and human-friendly thin-film thermoelectric generators, used for micro-energy harvesting. In this study, we investigated the synthesis and thermoelectric applications of a Ge-based ternary alloy thin film, GeSiSn. The solid-phase crystallization of the highly densified amorphous precursors allowed the formation of high-quality polycrystalline GeSiSn layers on an insulating substrate. The small compositions of Si and Sn in GeSiSn ( < 0.15 and < 0.05) lowered the thermal conductivity (3.1 W m K) owing to the alloy scattering of phonons, while maintaining a high carrier mobility (approximately 200 cm V s). The solid-phase diffusion of Ga and P allowed us to control the carrier concentration to the order of 10 cm for holes and 10 cm for electrons. For both p- and n-type GeSiSn, the power factor peaked at = 0.06 and = 0.02, reaching 1160 μW m K for p-type and 2040 μW m K for n-type. The resulting dimensionless figure of merits (0.12 for p-type and 0.20 for n-type) are higher than those of most environmentally friendly thermoelectric thin films. These results indicate that group IV alloys are promising candidates for high-performance, reliable thin-film thermoelectric generators.
IV族材料是用于微能量收集的高可靠性和对人体友好的薄膜热电发电机的有前途的候选材料。在本研究中，我们研究了一种Ge基三元合金薄膜GeSiSn的合成及其热电应用。高度致密的非晶前驱体的固相结晶使得能够在绝缘衬底上形成高质量的多晶GeSiSn层。GeSiSn中Si和Sn的小组成分（<0.15和<0.05）由于声子的合金散射而降低了热导率（3.1 W m K），同时保持了较高的载流子迁移率（约200 cm V s）。Ga和P的固相扩散使我们能够将空穴的载流子浓度控制在10 cm量级，电子的载流子浓度控制在10 cm量级。对于p型和n型GeSiSn，功率因子在 = 0.06和 = 0.02时达到峰值，p型为1160 μW m K，n型为2040 μW m K。所得的无量纲品质因数（p型为0.12，n型为0.20）高于大多数环境友好型热电薄膜。这些结果表明，IV族合金是高性能、可靠的薄膜热电发电机的有前途的候选材料。
