Temperature characteristics of langasite surface acoustic wave resonators coated with SiO2 films

In this paper, the SiO2 temperature compensation layers were deposited on LGS SAW resonators. The temperature characteristics of SAW resonators with different thicknesses of SiO2 coating layers were investigated from room temperature to 450 °C. The results show that the SAW velocity, the turnover temperature, the first and second order temperature coefficients of frequency (TCF1 and |TCF2|) increase as the SiO2 films thickness increasing. The Q factor of the SAW resonator decreases greatly due to the poor quality of the SiO2 film. Zero TCF1 is achieved when the SiO2 coating layer is about 0.25 μm. The results show that the LGS SAW resonators can be temperature compensated by SiO2 coating layer.