Establishment of innovative thin film synthesis method for topology-controlled glass

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K19016
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 36:Inorganic materials chemistry, energy-related chemistry, and related fields
• Research Institution: Tohoku University (2023); Hokkaido University (2021-2022)
• Principal Investigator: ONO MADOKA 東北大学, 工学研究科, 教授 (20865224)
• Co-Investigator(Kenkyū-buntansha): JEEM MELBERT 北海道大学, 工学研究院, 特任助教 (00815805)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: シリコンフォトニクス / 半導体絶縁膜 / シリカガラス / 圧力 / 結晶基板 / アモルファス薄膜

Outline of Final Research Achievements

Silica glass, composed of SiO2, has attracted much attention as an important element for waveguides in silicon photonics and insulating films in semiconductors. We have found that large voids in bulk silica glass are reduced and the structure becomes homogeneous by applying high pressure at high temperatures. However, since physical pressure is difficult to test, we investigated the possibility of controlling the structure and physical properties by layering thin SiO2 amorphous films on a crystalline substrate with a lattice constant close to the pore size. As a result, it was found that the structure and thermal conductivity of the amorphous films change significantly depending on the type of crystal substrate, and that this can also be changed by the film thickness and thin film preparation method.

Free Research Field

光物性物理学

Academic Significance and Societal Importance of the Research Achievements

本研究はガラスの化学的圧力を使ったトポロジー制御という,これまでにない新しいやり方を用いたガラス構造の制御方法の提案と実証である.研究開始時には加圧したシリカガラスは密度が高く均質性が上がることから,熱伝導率が上がることを期待していた.これが逆に大きく下がったことから,工業的にはややインパクトが下がってしまったものの,アモルファスの熱伝導率が何によって決まるのかを明らかにする重要な知見となったと考えている.まだ完全に明らかではないが,今回の検討でアモルファス構造の変化と熱伝導率の間に強い相関があることが示されたので,今後ガラスの熱伝導率を高めるための指針としても意義が大きいと考えている.