Design and development of structural-anisotropic three-dimensional phononic crystal toward low thermal conductivity material

• Project/Area Number: 20H02621
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Aoyama Gakuin University
• Principal Investigator: Yasuaki Ishikawa 青山学院大学, 理工学部, 准教授 (70581130)
• Co-Investigator(Kenkyū-buntansha): 上沼 睦典 奈良先端科学技術大学院大学, 先端科学技術研究科, 准教授 (20549092)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥18,070,000 (Direct Cost: ¥13,900,000、Indirect Cost: ¥4,170,000); Fiscal Year 2022: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2021: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2020: ¥10,270,000 (Direct Cost: ¥7,900,000、Indirect Cost: ¥2,370,000)
• Keywords: 3次元周期的ナノ構造 / 構造異方性 / 熱伝導率 / ナノ構造 / ZnO / 薄膜 / 熱電材料

Outline of Research at the Start

レーザーを利用したナノ構造形成法により半導体薄膜内に3次元周期的ナノ構造を形成する。形成されたナノ構造は、膜厚・面内方向で周期性が大きさが異なる構造異方性を有している。この構造異方性が熱電物性に与える影響を明らかにすることで、より高性能な熱電発電材料開発に展開する。

Outline of Final Research Achievements

Introducing nanostructures in semiconductor materials is an effective way to lower the thermal conductivity. In this research, we developed a fabrication process of three-dimensional periodic nanostructures in ZnO materials. Evaluation of the thermal conductivity of the provided samples was carried out, as well.
We accomplished that the introduced three-dimensional periodic nanostructure gave us around 70% reduction of thermal conductivity. In addition, it is found that structural anisotropy of the three-dimensional periodic nanostructures is able to alter the thermal conductivity of each direction.

Academic Significance and Societal Importance of the Research Achievements

我々の身の回りには利活用できず廃棄されて熱が多量に存在している。これら廃熱を再利用する熱電素子を資源豊富な元素で実現することが求められている。更に、熱電材料の高性能化にはナノ構造の導入が効果的であるる。そこで、熱電素子化に有利かつ性能の更なる向上が期待できる3次元周期的ナノ構造体の実現を進めた。本構造導入による熱電物性の改善が本研究により初めて実証され、更なる改善に向けた提案も行われた。

Research Products

• [Presentation] Development of three-dimensional periodic nanostructured film using SU-8 template and solution-derived ZnO for the thermoelectric materials (2022)
  • Author(s): Naoya Miyajima, Itsuki Nakahara, Yasuaki Ishikawa
  • Organizer: 35th International Microprocesses and Nanotechnology Conference
  • Int'l Joint Research
• [Presentation] Relationship of Phase Shift Mask Design and Size of Three-Dimension Nanostructures (2020)
  • Author(s): P. Sihapitak, Y. Ishikawa, X. Wang, M. Uenuma, and Y. Uraoka
  • Organizer: The 27th International Workshop on Active-Matrix Flatpanel Displays-TFT Technologies and FPD Materials
  • Int'l Joint Research