High thermal stability of ultra-high temperature surface acoustic wave devices with multilayer composite electrodes

The main challenge to maintain high-temperature performance of surface acoustic wave (SAW) devices is to improve the high-temperature resistance of the interdigital transducers (IDT). This work reports on the development of the Pt-Rh alloy-based multilayered composite IDTs for high-temperature applications. Composite electrode-based wire-type resistors with different structures were prepared by magnetron sputtering, and their resistances and surface morphologies at temperatures up to 1600 degrees C were investigated. The proposed composite electrode has a structure of ZrO2 /Pt-Rh (10%) /Al2O3 /Pt-Rh (10%) /Al2O3 with a 40 nm ZrO2 protective layer at the top of the electrode. It has a 300 nm thickness Pt-Rh (10%) film, a 10 nm Al2O3 layer in the middle of Pt-Rh (10%) layer, and a 20 nm Al2O3 layer between the electrode and the substrate. The results showed that the composite electrodes could withstand a maximum operating temperature up to 1600 degrees C in air. The electrodes maintained excellent stability even after five cyclic thermal treatments at temperatures up to 1200 degrees C for one hour, and good stability after two cyclic thermal treatments up to 1400 degrees C for 1 h. The SAW devices based on AlN single-crystal piezoelectric film using the composite electrodes showed good stability at 1200 degrees C for 1 h.

Automated summary

This work focuses on the development of Pt-Rh alloy-based multilayered composite IDTs for high-temperature applications. The composite electrodes were prepared by magnetron sputtering, and their resistance and surface morphology were investigated at temperatures up to 1600 degrees C. The results showed that the composite electrodes could withstand a maximum operating temperature of 1600 degrees C in air.