C-Axis-Tilted ScAlN Film on Silicon Substrate for Surface Acoustic Wave Device

Takumi Tominaga, Shinji Takayanagi, Takahiko Yanagitani

Research output: Contribution to journalConference articlepeer-review

Abstract

ScAlN films exhibit higher piezoelectricity than the AlN films. Furthermore, recent studies have shown that the appearance of ferroelectricity in the ScAlN films. Therefore, ScAlN films are currently being investigated to explore their potential for use in elastic wave devices for next-generation mobile networks. Surface acoustic wave (SAW) devices with a high frequency (gigahertz-range), a high electromechanical coupling coefficientboldsymbol{K}{\boldsymbol{2}} and a highmathbf{Q} factor are required for filters and duplexers in the smartphones. Recently, ScAlN film/high BAW velocity substrate (e.g. diamond and SiC) structures were reported to have a highboldsymbol{K}{\boldsymbol{2}}, whereas their substrates are very expensive. Conversely, silicon is known as inexpensive substrates and is suitable for device integration. We have previously shown thatboldsymbol{K}{\boldsymbol{2}} values of crystal class (6mm) including ZnO and AlN increases with their c-axis tilt angle. In this study, we theoretically demonstrated that the electromechanical coupling coefficientboldsymbol{K}{\boldsymbol{2}} of SAW propagating in ScAlN film/Si substrate layered structure increases with c-axis tilt angle. In addition, a c-axis tilted ScAlN films were prepared on Si substrates by a sputtering method.

Original languageEnglish
JournalIEEE International Ultrasonics Symposium, IUS
DOIs
Publication statusPublished - 2021
Event2021 IEEE International Ultrasonics Symposium, IUS 2021 - Virtual, Online, China
Duration: 2011 Sep 112011 Sep 16

Keywords

  • Electromechanical coupling coefficient
  • ScAIN film
  • Self-shadowing effect
  • Silicon
  • Sputtering deposition
  • Surface acoustic wave

ASJC Scopus subject areas

  • Acoustics and Ultrasonics

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