LiTaO ₃ ‐ on‐YAG surface acoustic wave resonator with low TCF and spurious modes mitigation

Abstract Surface acoustic wave (SAW) resonators employing LiTaO 3 piezoelectric platelet on yttrium aluminium garnet (YAG) substrate are designed with a low temperature coefficient of frequency (TCF) and spurious modes suppression. Transverse modes in the structure are suppressed through the transducer topology, while the higher‐order plate‐guided modes are inherently suppressed by the YAG‐based device platform. Fabricated 1.7 GHz SAW resonator demonstrates significant suppression of the higher order spurious modes as compared to their counterpart on Si (100) base while retaining very low TCF and Q factor of about 2700. The maximum resonance‐to‐antiresonance (R‐aR) bandwidth is estimated to be 4.8%. YAG‐based SAW platform is an alternative to the classical Si‐based SAW platform in radio frequency filters in the lower GHz range, offering high performance and simplifying the stack topology by eliminating the need for additional charge trapping layers. Preliminary estimations show that YAG being commercially viable in photonics is scalable to 4″–6″ low‐cost wafers, required in the RF SAW industry.