2018 Fiscal Year Final Research Report

Study of giant Seebeck coefficient by thermoelectric nanowire using nano-scale control

Research Project

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Project/Area Number	15H04142
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	Structural/Functional materials
Research Institution	Saitama University
Principal Investigator	HASEGAWA Yasuhiro 埼玉大学, 理工学研究科, 准教授 (60334158)
Co-Investigator(Kenkyū-buntansha)	遠藤彰東京大学, 物性研究所, 助教 (20260515) 中村浩章核融合科学研究所, ヘリカル研究部, 教授 (30311210) 村田正行国立研究開発法人産業技術総合研究所, エネルギー・環境領域, 研究員 (80717695) 小峰啓史茨城大学, 工学部, 准教授 (90361287)
Project Period (FY)	2015-04-01 – 2019-03-31
Keywords	巨大ゼーベック効果 / ナノ加工 / ナノワイヤー熱電変換素子 / ホール係数測定 / 熱電気物性
Outline of Final Research Achievements	Aim of this study is to improve efficiency of thermoelectric conversion by thermoelectric material like bismuth which is one of most material. A strategy has been introduced into the material using nano-wire geometry with nano-scale diameter and milli-scale length, making it possible to occur quantum effect like one-dimensional density of state to enhance its performance; however, the handling of the nanowire has been quite difficult due to its size and fragile. In addition, several local electrodes are required to measure its properties. We have employed nano-fabrication technique we have proposed and have successfully fabricated the electrodes for the measurement. Finally, the measurements of resistivity, magneto-resistivity, and Hall coefficient were performed simultaneously. The experimental results showed us that the mobility suppression in low temperature region was derived from the limitation of the mean free path of the carrier.
Free Research Field	熱電気物性，ナノ加工
Academic Significance and Societal Importance of the Research Achievements	超低炭素社会・省資源社会を目指したクリーンエネルギー需要が高まっている中、熱（温度差）から電気への直接エネルギー変換を可能にする熱電変換現象に着目している。資源の乏しい日本にとって、二酸化炭素を輩出しないエネルギー創成研究は重要であることは知られているものの、熱電変換によるエネルギー変換効率は10％以下と小さい。本研究では、材料をナノスケールにすることで採り入れることが出来る量子効果に着目し、エネルギー変換効率の向上を目指している。