Phonon scattering behavior at metal/insulator phase transition interfaces

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14092
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Nagaoka University of Technology
• Principal Investigator: Baba Masaaki 長岡技術科学大学, 工学研究科, 助教 (10826176)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 金属ー絶縁体相転移

Outline of Final Research Achievements

This study focuses on the phonon scattering behavior at metal/insulator interfaces. To achieve this, I established thin-film deposition techniques for VO2 and W-doped VO2 (W-VO2), and measured the thermophysical properties of bulk VO2. VO2 films deposited by sputtering method exhibited a resistance change of over three orders of magnitude. Furthermore, the phase transition temperature of the deposited W-VO2 was lower than that of pure VO2, indicating that the phase transition temperature can be controlled through W doping. I fabricated VO2 sintered bodies with a relative density exceeding 95% of the theoretical density. By measuring the latent heat, specific heat, and thermal conductivity of these sintered bodies, the thermophysical properties of the single-phase VO2 were clarified.

Free Research Field

伝熱工学

Academic Significance and Societal Importance of the Research Achievements

本研究で用いた成膜手法は，スパッタリング法によりアモロファス相のVO2を成膜し，熱処理によって結晶化させる手法である．この手法は，大面積の成膜が可能，成膜時に酸素の調整が不要，基板の加熱が不要という利点があり，他の成膜手法と比べて工業的に有利である．本研究では，この成膜手法で未知であった熱処理条件と膜の物性との関係を明らかにし，MITに伴う抵抗変化が大きいVO2膜を作製できる条件を明らかにした．この成果は，VO2膜を用いたデバイスの製品化に貢献すると考えられる．