Dual Mode Thin Film Bulk Acoustic Resonators (FBARs) Based on AlN, ZnO and GaN Films with Tilted c-Axis Orientation

摘要

Thin film bulk acoustic wave resonators (FBAR) using piezoelectric AlN, ZnO and GaN thin films have attracted extensive research activities in the past years. Highly c-axis oriented (normal-plane orientation) binary semiconductor piezoelectric thin films are particularly investigated for resonators operating at the fundamental thickness longitudinal mode. Depending on the processing conditions, tilted polarization (c-axis off the normal direction to the substrate surface) is often found in the as-deposited piezoelectric thin films, which leads to the coexistence of thickness longitudinal mode and shear mode for the thin film resonators.