Elucidation of the key factors determining the piezoelectric properties of epitaxial piezoelectric thin films on Si substrates using synchrotron X-ray diffraction

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14200
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: Osaka Metropolitan University (2022-2023); Osaka Prefecture University (2021)
• Principal Investigator: Goon Tan 大阪公立大学, 国際基幹教育機構, 准教授 (00806060)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 圧電特性 / X線構造解析 / 強誘電体薄膜

Outline of Final Research Achievements

The application of piezoelectric materials as thin films in piezoelectric MEMS (Micro-Electro-Mechanical Systems) spans a wide range, from microactuators to piezoelectric sensors. From the perspective of MEMS processing, it is essential to fabricate high-quality epitaxial piezoelectric thin films on Si substrates, and thoroughly investigate their crystallographic and piezoelectric properties. However, such studies are still rare.
In this research, we fabricated large-area epitaxial growth of lead zirconate titanate (Pb(Zr,Ti)O3, PZT) thin films on Si substrates with buffer layers. Using synchrotron X-ray diffraction, we conducted crystal structure analysis under applied voltage on the epitaxial piezoelectric thin films on Si substrates. This allowed us to elucidate the key crystallographic factors determining the piezoelectric properties of the thin films.

Free Research Field

圧電薄膜材料

Academic Significance and Societal Importance of the Research Achievements

本研究では、バッファ層付きSi基板上に作製した高品質なエピタキシャルPZT薄膜に対し、電圧を印加しながらのXRD（X線回折）測定を行い、圧電薄膜の格子ひずみといった微視的な結晶構造変化が巨視的な圧電特性にどのように寄与するのかを調査した。その結果、電圧印加下のPZT薄膜のX線回折スポットから得られた結果は、巨視的な逆圧電特性における電圧依存性と整合し、組成比の異なるPZT薄膜それぞれの圧電性の起源を解明する手がかりを得ることができた。これにより圧電特性を最大限に引き出せるような材料設計指針を検討し、圧電MEMSの性能向上、非鉛圧電薄膜の創製など、新しい展開をもたらすことが期待された。