Sezawa-Mode Surface Acoustic Wave Resonators in Pulsed-Laser-Deposited Pb_0.9Ba_0.1(Zr_0.52,Ti_0.48)O₃ on Bulk Silicon

Barium-doped Lead Zirconate Titanate Pb_0.9Ba_0.1(Zr_0.53Ti_0.47)O₃ films with a (001)-dominant orientation were deposited on bulk silicon (Si) substrates using pulsed laser deposition (PLD). Due to the large electromechanical coupling coefficient (K²) of the P(B)ZT layer and the larger shear modulus of the Si substrate compared to the P(B)ZT film, it is possible to obtain higher-order acoustic-resonant modes (Sezawa mode) with SAW wavelength (λ)-piezoelectric film thickness (h) ratios below h/λ < 0.2. Due to the ferroelectric properties of the P(B)ZT film, the resonator's performance can be improved by increasing the electric polarization. Consequently, the measured quality (Q) factors can be improved from 50 to 200 and the K² values can be improved from 2 to 5% with the resonance frequency ranging from 275 to 500 MHz.