2019 Fiscal Year Final Research Report
High-coupling longitudinal-type leaky surface acoustic wave using bonded dissimilar material structure and its application to high-frequency filter for next generation communications
| Project/Area Number |
17H03233
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | University of Yamanashi |
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Principal Investigator |
KAKIO Shoji 山梨大学, 大学院総合研究部, 教授 (70242617)
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| Co-Investigator(Kenkyū-buntansha) |
水野 潤 早稲田大学, ナノ・ライフ創新研究機構, 上級研究員(研究院教授) (60386737)
鈴木 雅視 山梨大学, 大学院総合研究部, 助教 (60763852)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | SAWフィルタ / 縦型リーキー弾性表面波 / 異種材料接合 / 高周波化 / 高結合化 / 高Q化 / 高安定化 |
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| Outline of Final Research Achievements |
For the evolution of next-generation mobile communication systems, surface acoustic wave (SAW) devices with higher frequency and wide bandwidth are strongly demanded. The longitudinal-type leaky surface acoustic wave (LLSAW) has advantageous for application to high-frequency SAW devices since LLSAWs have a higher phase velocity than the general SAWs. However, LLSAWs exhibit inherent attenuation because they lose energy by continuously radiating bulk waves into the substrate.
In this study, it was found theoretically and experimentally that when the LiNbO3 or LiTaO3 thin plate with a smaller thickness than one wavelength bonded to a quartz substrate, the attenuation was reduced remarkably and the electromechanical coupling factor of the LLSAW was increased to two to three times that in the single substrate. Moreover, a shear-horizontal-type LSAW with high performance was obtained by utilizing the bonded structure.
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| Free Research Field |
通信工学，超音波エレクトロニクス
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| Academic Significance and Societal Importance of the Research Achievements |
次世代通信システムの実現に向けて，LiTaO3等の圧電基板を用いた弾性表面波(SAW)フィルタの高周波化と広帯域化が強く要請されている．縦波型リーキーSAW(LLSAW)は，通常のSAWと比べて1.5～2倍の伝搬速度を持つため，SAWフィルタの高周波化に有利であるが非常に大きな伝搬損失を有する．
本研究では，異種材料接合技術を用いて１波長以下の厚みをもつ圧電薄板と水晶支持基板を接合すると，弾性波エネルギーが薄板内に集中するため，LLSAWの伝搬損失が格段に低減し，広帯域化に必要な結合係数が２～３倍に増加することを明らかにし，スマートフォン等の端末用高周波フィルタへの適用可能性を示した．
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