Thin film bulk acoustic wave resonators tuning from first principles

Abstract

Being important for the antiresonance frequency tuning of tunable thin Film Bulk Acoustic wave Resonators (FBARs), the non-linear electrostrictive coefficient was for the first time calculated for BaTiO3 and SrTiO3 using ab initio methods. Further, taking into account the small difference of obtained values for BaTiO3 and SrTiO3 these results were linearly interpolated to the BaxSr1−xTiO3 (BST) compositions. The obtained values are consistent with previously made order-of-magnitude estimates. Using parameters obtained with first principles calculations, we simulated the resonance parameters of BST based tunable FBARs. Resulting antiresonance tuning was smaller than expected due to the compensation of two competing terms conditioned by linear and non-linear electrostrictions. Our calculations confirm that, for tunable FBAR modeling, it is important to use a polarization-based Landau free energy expansion taking into account both non-linear electrostriction and background permittivity.

Intrinsically tunable bulk acoustic wave resonators based on sol-gel grown PMN-PT films

“…1,4,18,[23][24][25][26] Recent ab initio calculations indicate that the non-linear electrostrictive coefficient is negative in the whole range of the BSTO composition. 27 It means that the term l/2 dominates in the sum of c þ l/2 with x < 0.5. However, the BSTO BAW resonators with x !…”

Theoretical Simulation and Optimization on Material Parameters of Thin Film Bulk Acoustic Resonator

“…Chao et al studied the electrode effects of FBAR by Butterworthvan Dyke (BVD) equivalent circuit [11], and Chen and Wang calculated the effective electromechanical coupling coefficient of FBAR [12], and Zhang et al applied resonant spectrum method to characterize piezoelectric films in FBAR [13]. Besides, our research group published the research about the electrode effect of FBAR [14], and Naumenko analyzed the propagation of acoustic wave in FBAR with Finite Element Method [15], and Kvasov and Tagantsev calculated the nonlinear electrostrictive coefficient with first principles [16]. All of above researches aim at the excellent FBAR performance because the resonance frequency, the effective coupling coefficient, and the accurate optimization for the design of FBAR are the key points for FBAR performance.…”