Ultra-High Q of 11000 in Surface Acoustic Wave Resonators by Dispersive Modulation

In this work, a method to reduce the acoustic energy loss has been proposed, and the GHz ultra-high <inline-formula> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> acoustic wave resonators based on the LiTaO3-on-SiC (LTOSiC) substrate were demonstrated. By modulating the ratio of the LiTaO3 film thickness to interdigital transducer pitch (<inline-formula> <tex-math notation="LaTeX">${h}_{\textit {LT}}/\lambda {)}$ </tex-math></inline-formula>, the adjoined X and Z polarization components of the guided shear horizontal surface acoustic wave (SH-SAW) can be significantly diminished, and the acoustic energy loss can be effectively reduced. The modulated dispersive SH-SAW resonator shows an excellent Bode-<inline-formula> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> of 11000 and a Figure of merit (FoM) of 620. In addition, as predicted by the propagation loss of the acoustic delay lines on LTOSiC, high <inline-formula> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> factors can be achieved when <inline-formula> <tex-math notation="LaTeX">${h}_{\textit {LT}}/\lambda $ </tex-math></inline-formula> is less than 0.14. These results suggest the feasibility of developing low-loss acoustic devices on the LTOSiC substrate for wireless communications.