Analysis of dual-mode thin film bulk acoustic resonators based on polar c-axis tilted wurtzite gallium nitride

Abstract

We present the analytical study of dual-mode thin film bulk acoustic resonators (FBARs) based on wurtzite gallium nitride (GaN) thin films with tilted c-axis orientation. The normal-plane and in-plane electric polarization vector components caused by the titled c-axis orientation induce the coexistence of the thickness longitudinal and thickness shear modes in the thin film resonator. Due to the c-axis orientation dependency of material properties including elastic stiffness, dielectric constants, and piezoelectric coefficients, bulk wave properties of FBARs including acoustic velocity and electromechanical coupling coefficient, and electrical impedance spectra are greatly affected by the tilt angle. It is found that the pure longitudinal mode occurs at θ=0° and 66.4°, and the pure shear mode occurs at θ=42.8° and 90°. In addition, the electromechanical coupling coefficient for thickness shear mode has a maximum value 3.18% at θ=34.2°, which is larger than the maximum value for pure thickness longitudinal mode 2.44% at θ=0°. The calculation results show that FBARs based on tilted c-axis wurtzite GaN thin films are promising for frequency control device design and applications.

Analysis of Thickness Vibrations of C-Axis Inclined Zig-Zag Multi-layered Zinc Oxide Thin Film Resonators

“…(11)(12)(13)(14)(15), the continuity condition on the contact surface between k and k + 1 (k = −(N−1) . .…”

“…In a work performed by Foster [7], the analysis of cadmium sulphide and ZnO thin-film transducers is presented. An analysis of dual-mode thin film bulk acoustic resonators based on polar C-axis tilted wurtzite gallium nitride can be found in [12]. In the authors' previous work [3], theoretical analysis for the frequency equation, mode shape, and impedance characteristics of a single-layered and C-axis inclined AlN FBAR connected with external impedance was carried out.…”

Wideband Multimode Transducer Consisting of c-Axis Tilted ZnO/c-Axis Normal ZnO Multilayer

“…19,20) The physical constant tensors of the ZnO layer were assumed to be identical to the single crystal values and properly rotated in accordance with the c-axis tilt angle of the ZnO layer. 23) 3. Crystalline Orientation of the Transducer Figure 3 shows the ¼-scan profile curve of Au(111) in the multilayer transducer [ Fig.…”

Design and Optimization of the Dual-Mode Lamb Wave Resonator and Dual-Passband Filter

“…John D. Larson et al [12] proposed a dual-passband filter based on piezoelectric resonators via two piezoelectric layers with oppositely grown orientation. A theoretical analysis of thickness-longitudinal and thickness-shear dual-mode resonators based on c-tilted ZnO and AlN films was presented by L. Qin et al [13,14]. Moreover, Y. Zou et al [15] further studied the dual-mode resonators with c-tilted films using Finite Element Analysis (FEA) and proposed a potential application for the dual-passband filter.…”