Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature Conditions

This paper investigates the performance of scandium-doped aluminum nitride (AlScN) piezoelectric micromachined ultrasonic transducers (PMUTs) under extreme high-temperature conditions. Key findings include significant warpage due to thermal expansion, increasing from 0.306 µm at room temperature to 1.823 µm at 150°C. Resonant frequency showed a linear drift, with frequency shifts reaching 44\% at 200°C. The impedance phase increased from -41.56° at room temperature to +2.45° at 200°C, and the electromechanical coupling coefficient rose to between 21.4\% and 68.6\% in the temperature range of 100°C to 140°C. High-temperature cycling also revealed irreversible frequency shifts, indicating lasting thermal effects on device integrity. These results provide crucial insights into the behavior of AlScN-based PMUTs in harsh environments, guiding their design and reliability evaluation for high-temperature applications.