8-25 GHz Broadband Experimental Quality Factor Extraction of 30% ScAlN with Acoustic Delay Lines

This work reports on the first experimental characterization of the Quality Factor (Q) of the Cross-sectional Lamé Mode (CLM) in 30% sC-doped Aluminum Nitride (ScAlN) above the X-band. By utilizing three high-crystallinity ScAlN films with thicknesses of 100, 150, and 280 nm, as well as more than 300 Acoustic Delay Lines (ADL), the intrinsic material-based limitation of the Q of ScAlN in the 8-25 GHz range is analyzed in depth. The results confirm a decreasing trend with frequency. The trustworthiness of the method is verified by extracting the Q from ADLs in AlN, obtaining values close to the theoretically calculated ones. The current results aim to quantitatively inform the reader on the achievable maximum Q from microacoustic resonators operating in the same resonant mode. Additionally, the methodology can be promptly extended to other resonant modes.