Surface Acoustic Wave Devices Based on High Quality Temperature-Compensated Substrates

Abstract

We report surface acoustic wave (SAW) devices based on two kinds of novel and optimized high quality piezoelectric substrates. SAW devices with excellent temperature stability and electromechanical coupling coefficient using the layered structures LiTaO3 (LT)/Si and LiNbO3 (LN)/SiO2/Si as the substrates are fabricated. These structures exhibit superior temperature performance than the conventional LT, LN substrates and reported related works with the SiO2 interlayer and Si substrate providing temperature compensation and thermal diffusion block, respectively. SAW device fabricated on the optimized LT/Si substrate shows a parabolic frequency–temperature relation with near zero temperature coefficient of frequency (TCF) in a low temperature range. SAW device fabricated on the novel LN/SiO2/Si substrate shows excellent performance with near constant TCF about −18 ppm/°C and electromechanical coupling coefficient ( $K^{2}$ ) near 18.69%. Theoretical analysis and performance comparison with reported works are presented to elucidate the temperature compensation mechanism of the proposed layered structures.