Single-Crystalline LiTaO3 Film-Based High-Frequency Surface Acoustic Wave Resonators and Electronics Applications

Ultrahigh-frequency surface acoustic wave (SAW) devices with high quality (
$Q$
) factors are essential components for the next-generation wireless communication system. In this work, we reported high-performance and ultrahigh-frequency SAW devices with single-crystalline LiTaO
₃
/SiO
₂
/Si [LT-on-insulator (LTOI)] multilayered heterostructure. The fabricated SAW resonators exhibited multi-resonant modes (Rayleigh, Sezawa, and LLSAW mode) with the frequency ranging from 1.81 to 8.33 GHz. Especially, the SAW resonator with the Rayleigh wave frequency over 5.0 GHz and high
$Q$
value around 2300 with a wavelength of 600 nm was realized. The variation of the phase velocity, the
$Q$
factor for each resonant mode, and the effective coupling coefficients (
$k^{2}_{\mathrm {eff}}$
) versus the normalized LiTaO
₃
film thickness were systematically investigated. The proposed high-frequency SAW based on LTOI multilayered heterostructure possesses the low temperature coefficient of frequency (TCF, −20 ppm/K). Furthermore, a high-performance SAW bandpass filter with the center frequency of ~3.5 GHz was achieved. The work shows the great potential of the LiTaO
₃
single-crystalline thin-films-based SAW for ultrahigh frequency electronics applications.