Wave phonon engineering based on monolayer NEMS functionalized using sub-nanometer ion beam

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K20442
• Project/Area Number (Other): 19H05520 (2019)
• Research Category: Grant-in-Aid for Challenging Research (Pioneering)
• Allocation Type: Multi-year Fund (2020); Single-year Grants (2019)
• Review Section: Medium-sized Section 28:Nano/micro science and related fields
• Research Institution: Japan Advanced Institute of Science and Technology
• Principal Investigator: MIZUTA Hiroshi 北陸先端科学技術大学院大学, 先端科学技術研究科, 教授 (90372458)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: グラフェン / NEMS / フォノン / ヘリウムイオンビーム / 熱整流素子

Outline of Final Research Achievements

Various nanophononic structures were fabricated on suspended graphene by using electron beam lithography combined with focused He+ ion beam milling technology. Nanoscale heat phonon transport properties were measured by using unique Differential Thermal Leakage (DTL) method. Thermal rectification phenomena were observed for the first time for an asymmetric nanophononic channel structure on which only a half area was carved into two-dimensional array of circular nanopores of 5 to 6 nm in diameter. The thermal rectification ratio of approximately 80 % was obtained at the environmental temperature of 150 K. Furthermore, over 40% rectification ratio was successfully achieved at room temperature for an asymmetric channel structure with six parallel graphene nanoribbons of 30 nm in width in parallel.

Free Research Field

ナノエレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

原子層材料グラフェンのNEMS技術と電子線直接描画／集束ヘリウムイオンビーム超微細加工技術を初めて融合させ、宙づりグラフェン上にシングルナノメータスケールのフォノニック結晶構造を形成し、熱フォノン輸送を制御して熱整流素子の原理検証に成功した独創性の高い研究成果である。現在のナノ集積回路やパワーデバイスで深刻な問題となっている局所発熱に対する新たなサーマルマネジメント技術を拓くだけでなく、従来の熱電変換技術のようにレアメタルや毒性の強い重金属を含む材料を使用せず、安全で環境に優しい炭素材料で低価格のシステムを実現できるため、新学術領域開拓・新産業展開両面で波及効果が大きい。