Super High-Frequency Scandium Aluminum Nitride Crystalline Film Bulk Acoustic Resonators

Abstract

This work presents promising results of overtone thickness resonance modes of film bulk acoustic resonators (FBARs) operating at Ku band, traditionally perceived unachievable by acoustic devices. We take advantage of the epitaxial growth of the bottom metal electrode, as well as the piezoelectric layer to improve thin-film crystal quality and hence quality factor (Q). This work is the first demonstration of a multi-GHz FBAR realized on single-crystalline Sc <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.12</sub> Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.88</sub> N/Mo stack.