A novel micromachined ultrasonic transducer based on single-crystal piezoelectric silicon carbide thin film

This work reports on the first experimental demonstration of piezoelectric micromachined ultrasonic transducers (PMUTs) based on the intrinsic piezoelectricity of c-axis 4H-silicon carbide (4H-SiC), establishing its viability for acoustic transduction in extreme environments. Fabricated on silicon carbide on insulator (4H-SiCOI) substrates via standard microelectromechanical-system processes, the devices exhibit distinct flexural resonant modes verified by laser Doppler vibrometry, confirming effective electromechanical transduction. The measured fundamental resonant frequencies adhere strictly to classical thin-plate vibration theory across a broad range of diaphragm geometries. Furthermore, the analysis of a PMUT array reveals exceptional inter-unit uniformity with tightly controlled frequency distributions. These results validate 4H-SiC as a compelling alternative to conventional AlN and PZT, paving the way for integrated piezoelectric sensing systems in high-temperature and high-radiation scenarios.