Spurious-Free Lithium Niobate Bulk Acoustic Wave Resonator with Grounded-Ring Electrode
New piezoelectric chip operates at 600°C, survives 900°C with 65 nm/V efficiency.
A research team from Stanford University and other institutions has published a breakthrough in piezoelectric transducer technology. Their paper, "Spurious-Free Lithium Niobate Bulk Acoustic Wave Resonator with Grounded-Ring Electrode," details a new type of piezoelectric micromachined ultrasonic transducer (PMUT) built on a single-crystal lithium niobate (LN) platform. The key innovation is a bimorph structure using a 20 µm thick, periodically poled piezoelectric film (P3F) without intermediate electrodes, combined with a grounded-ring electrode design that suppresses spurious modes. This results in a mechanically robust 775 kHz flexural mode device with a high quality factor (Q) of 200 and an extracted electromechanical coupling coefficient (k²) of 6.4%.
The device's high performance translates to a remarkable transmit efficiency of 65 nanometers per volt. Most significantly, the team leveraged the inherent thermal stability of lithium niobate to demonstrate extreme-temperature resilience. The PMUT maintained stable operation at temperatures up to 600 degrees Celsius and survived brief exposures up to 900°C. This performance far exceeds the limits of conventional silicon-based MEMS and other piezoelectric materials like aluminum nitride or PZT, which degrade well below these temperatures. The work establishes LN as a prime material platform for creating sensors that can function directly in the intense heat of jet engines, industrial furnaces, or deep-earth drilling equipment, enabling real-time monitoring in environments previously inaccessible to microelectronics.
- Uses a 20 µm thick, periodically poled lithium niobate (P3F) film for a robust bimorph actuator without internal electrodes.
- Achieves a high electromechanical coupling (k²) of 6.4% and efficiency of 65 nm/V at 775 kHz with a Q factor of 200.
- Demonstrates unprecedented thermal resilience with stable operation at 600°C and survival up to 900°C, enabling harsh-environment sensing.
Why It Matters
Enables durable micro-sensors for real-time monitoring inside jet engines, nuclear reactors, and industrial furnaces, revolutionizing condition-based maintenance.