Loss reduction of longitudinal-type leaky surface acoustic wave by loading with high-velocity thin film and its application to high-frequency filter

2016 Fiscal Year Final Research Report

• Project/Area Number: 26420269
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electronic materials/Electric materials
• Research Institution: University of Yamanashi
• Principal Investigator: KAKIO Shoji 山梨大学, 総合研究部, 教授 (70242617)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 弾性表面波 / LiNbO3 / ScAlN薄膜 / 低損失フィルタ / 異種材料接合

Outline of Final Research Achievements

For the evolution of next-generation mobile communication systems, surface acoustic wave (SAW) devices with higher frequency 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 experimentally for the LLSAW propagating on LiNbO3 substrate that, the losses can be reduced by loading with a ScAlN thin film with a higher velocity than the substrate. Moreover, it was also found theoretically and experimentally that when the LiNbO3 or LiTaO3 thin plate with a smaller thickness than one wavelength bonded to an quartz or sapphire substrate with a high phase velocity, the electromechanical coupling factor of the LLSAW was increased to two to three times that in the single substrate.

Free Research Field

通信工学，超音波エレクトロニクス