c-Axis-Tilted ScAlN Film on Silicon Substrate for Surface Acoustic Wave Device
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2021-09-11 |
| Authors | Takumi Tominaga, Shinji Takayanagi, Takahiko Yanagitani |
| Institutions | Waseda University, Doshisha University |
| Citations | 2 |
Abstract
Section titled “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 coefficient <tex xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>$\boldsymbol{K}^{\boldsymbol{2}}$</tex> and a high <tex xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>$\mathbf{Q}$</tex> 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 high <tex xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>$\boldsymbol{K}^{\boldsymbol{2}}$</tex> , whereas their substrates are very expensive. Conversely, silicon is known as inexpensive substrates and is suitable for device integration. We have previously shown that <tex xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>$\boldsymbol{K}^{\boldsymbol{2}}$</tex> 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 coefficient <tex xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”>$\boldsymbol{K}^{\boldsymbol{2}}$</tex> 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.
Tech Support
Section titled “Tech Support”Original Source
Section titled “Original Source”References
Section titled “References”- 2010 - Giant shear mode electromechanical coupling coefficient $k$15 in c-axis tilted ScAlN films
- 2017 - Film growth of c-axis tilted ScAlN on the sapphire substrate for SAW devices