Ultra High Temperature Saw Sensors Based on Signle Crystalline AlN and Multilayer Composite Electrode

A newly constructed surface acoustic wave (SAW) device was used to broaden the applicability of sensors at ultra-high temperatures (> 1000°C) and increase the stability under ultra-high temperatures. The choice of piezoelectric substrate and the design of temperature-resistant electrodes were both addressed in this design. We investigate the stability of AlN piezoelectric film for ultra-high-temperature applications, based on the reliability of AlN/Sapphire structure in high-temperature applications. In addition, a Pt-Rh and Al2O3 composite electrode structure was constructed and studied. Finally, a high temperature sensing resistant experiment based on single crystalline piezoelectric AlN was carried out, demonstrating that the developed SAW device can still work well at temperatures up to 1200°C.The frequency response change of the SAW sensor under high temperatures was obtained and analyzed.