Control of defects in polycrystalline ZnO thin films for chemical sensor

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04582
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: Kochi University of Technology
• Principal Investigator: Makino Hisao 高知工科大学, システム工学群, 教授 (40302210)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 酸化亜鉛 / 欠陥 / 結晶極性 / ガスセンサ / 化学センサ / 粒界 / 酸化物

Outline of Final Research Achievements

Zinc oxide, a semiconductor oxide, is a safe material used as sunscreen and medicine, while it is also widely expected to be a functional material for light emission, solar cells, and chemical sensors. In this study, we have controlled the properties derived from the crystal structure, such as crystal polarity, in polycrystalline zinc oxide thin films deposited by the sputter deposition method, which enables low-temperature and large-area deposition, and clarified the characteristics and properties of defects, which are imperfections in the crystal formed in the films. Furthermore, the detection sensitivity of gas sensors as a functional application of the defects produced in polycrystalline thin films, such as lattice defects and crystal grain boundaries, was improved, indicating the possibility of improving sensor characteristics that will contribute to safety and security in the future hydrogen society.

Free Research Field

薄膜・表面界面物性

Academic Significance and Societal Importance of the Research Achievements

酸化亜鉛（ZnO）はc軸方向に自発分極を持ち、薄膜特有の歪によるピエゾ分極効果など、多彩な機能性材料として期待されている。ZnO多結晶薄膜においてAl極薄膜を用いた極性制御を実現し、極性由来の特徴が電気特性や化学反応性に違いを生むことが示された。学術的な観点では、Al金属膜とZnOの界面反応の解明、界面化学結合を利用した構造特性制御、多結晶薄膜に特有な粒界特性の改質などの新たな知見が得られた。機能応用の観点では、表面処理工程の最適化により反応サイトを制御しガス応答性を劇的に増大させる可能性がある。