Improvement of high-temperature stability of Al2O3/Pt/ZnO/Al2O3 film electrode for SAW devices by using Al2O3 barrier layer

Abstract

In order to develop film electrodes for the surface acoustic wave (SAW) devices operating in harsh high-temperature environments, novel Al2O3/Pt/ZnO/Al2O3 multilayered film electrodes were prepared by laser molecular beam epitaxy (LMBE) at 150 °C. The first Al2O3 layer was used as a barrier layer to prevent the diffusion of Ga, La, and Si atoms from the La3Ga5SiO14 (LGS) substrate to the film electrode and thus improved the crystalline quality of ZnO and Pt films. It was found that the resistance of the Al2O3/Pt/ZnO/Al2O3 electrode did not vary up to a temperature of 1150 °C, suggesting a high reliability of electrode under harsh high-temperature environments. The mechanism of the stable resistance of the Al2O3/Pt/ZnO/Al2O3 film electrodes at high temperature was investigated by analyzing its microstructure. The proposed Al2O3/Pt/ZnO/Al2O3 film electrode has great potential for application in high-temperature SAW devices.