Theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c-axis-tilted wurtzite ScAlN
Scandium aluminum nitride (ScAlN) has gained significant attention as a piezoelectric material for bulk acoustic wave (BAW) resonators, offering a promising alternative to conventional aluminum nitride (AlN) due to its superior piezoelectric properties. Recent advancements in ScAlN film fabrication...
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AIP Publishing LLC
2025-06-01
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| Series: | AIP Advances |
| Online Access: | http://dx.doi.org/10.1063/5.0256428 |
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| author | Takumi Tominaga |
| author_facet | Takumi Tominaga |
| author_sort | Takumi Tominaga |
| collection | DOAJ |
| description | Scandium aluminum nitride (ScAlN) has gained significant attention as a piezoelectric material for bulk acoustic wave (BAW) resonators, offering a promising alternative to conventional aluminum nitride (AlN) due to its superior piezoelectric properties. Recent advancements in ScAlN film fabrication techniques, enabling control over the Sc concentration (x) and c-axis tilt angle (θ), have motivated this study to theoretically investigate the BAW propagation characteristics of c-axis-tilted ScxAl1−xN as a function of x and θ. In c-axis-tilted ScAlN, quasi-longitudinal and quasi-shear waves coupled with piezoelectricity propagate, with their electromechanical coupling coefficient (K2) values increasing sharply with x and reaching maximum values under different conditions: θ = 0° for quasi-longitudinal waves and θ = 32.35° for quasi-shear waves. At x = 0.43, where ScAlN exhibits its highest piezoelectricity, the maximum K2 values are 24.7% and 32.1% for quasi-longitudinal and quasi-shear waves, respectively, 4.3 and 5.3 times higher than those of AlN. This increase in K2 is attributed to a reduction in elastic constants and enhanced piezoelectric stiffening of ScAlN with increasing x, accompanied by a decrease in phase velocity. The substantial enhancement in K2 values for quasi-longitudinal and quasi-shear waves with increasing x underscores the primary advantage of c-axis-tilted ScAlN. This improvement enables c-axis-tilted ScAlN to overcome the limitations of AlN in BAW propagation characteristics, offering the potential for advanced performance in BAW resonators. |
| format | Article |
| id | doaj-art-a95bdfdb73b248869ae72ad3a150e8ad |
| institution | DOAJ |
| issn | 2158-3226 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | AIP Publishing LLC |
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| spelling | doaj-art-a95bdfdb73b248869ae72ad3a150e8ad2025-08-20T03:14:57ZengAIP Publishing LLCAIP Advances2158-32262025-06-01156065315065315-910.1063/5.0256428Theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c-axis-tilted wurtzite ScAlNTakumi Tominaga0Independent Researcher, Mikawa-cho, Nagahama, Shiga 529-0111, JapanScandium aluminum nitride (ScAlN) has gained significant attention as a piezoelectric material for bulk acoustic wave (BAW) resonators, offering a promising alternative to conventional aluminum nitride (AlN) due to its superior piezoelectric properties. Recent advancements in ScAlN film fabrication techniques, enabling control over the Sc concentration (x) and c-axis tilt angle (θ), have motivated this study to theoretically investigate the BAW propagation characteristics of c-axis-tilted ScxAl1−xN as a function of x and θ. In c-axis-tilted ScAlN, quasi-longitudinal and quasi-shear waves coupled with piezoelectricity propagate, with their electromechanical coupling coefficient (K2) values increasing sharply with x and reaching maximum values under different conditions: θ = 0° for quasi-longitudinal waves and θ = 32.35° for quasi-shear waves. At x = 0.43, where ScAlN exhibits its highest piezoelectricity, the maximum K2 values are 24.7% and 32.1% for quasi-longitudinal and quasi-shear waves, respectively, 4.3 and 5.3 times higher than those of AlN. This increase in K2 is attributed to a reduction in elastic constants and enhanced piezoelectric stiffening of ScAlN with increasing x, accompanied by a decrease in phase velocity. The substantial enhancement in K2 values for quasi-longitudinal and quasi-shear waves with increasing x underscores the primary advantage of c-axis-tilted ScAlN. This improvement enables c-axis-tilted ScAlN to overcome the limitations of AlN in BAW propagation characteristics, offering the potential for advanced performance in BAW resonators.http://dx.doi.org/10.1063/5.0256428 |
| spellingShingle | Takumi Tominaga Theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c-axis-tilted wurtzite ScAlN AIP Advances |
| title | Theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c-axis-tilted wurtzite ScAlN |
| title_full | Theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c-axis-tilted wurtzite ScAlN |
| title_fullStr | Theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c-axis-tilted wurtzite ScAlN |
| title_full_unstemmed | Theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c-axis-tilted wurtzite ScAlN |
| title_short | Theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c-axis-tilted wurtzite ScAlN |
| title_sort | theoretical investigation of bulk acoustic waves with high electromechanical coupling coefficient in c axis tilted wurtzite scaln |
| url | http://dx.doi.org/10.1063/5.0256428 |
| work_keys_str_mv | AT takumitominaga theoreticalinvestigationofbulkacousticwaveswithhighelectromechanicalcouplingcoefficientincaxistiltedwurtzitescaln |