Cryogenic temperature sensing characteristics of surface acoustic wave resonator with high Q based on AlScN film

In cryogenic environments such as superconductivity and aerospace applications, surface acoustic wave (SAW) sensors offer significant advantages for low-temperature sensing due to their passive and wireless potential, which eliminates challenges associated with cabling and installation. This study employs COMSOL software to design and model a SAW resonator (SAWR), simulating its temperature–frequency characteristics within the range of 93–373 K. A high-Q SAWR was fabricated on a 1 μm scandium-doped aluminum nitride (AlScN) layer deposited via physical vapor deposition. Experimental characterization was conducted using an ultra-low-temperature testing platform to investigate the temperature–frequency properties of the Sc-doped AlN piezoelectric material and the impact of low temperatures on device performance. The results demonstrate that the designed AlScN SAWR exhibits a temperature sensitivity of 11.33 kHz/°C and temperature coefficient of frequency of −24.65 ppm/°C over the 93–373 K range. The device performs effectively in ultra-low-temperature sensing, with a high linearity (R2 = 0.997) and a Q factor reaching 16 479 at 93 K. These findings confirm the suitability of the proposed SAWR for efficient wireless and passive temperature sensing in ultra-low-temperature environments.