Radlab Grad Seminar: Thin Film Ferroelectric Bulk Acoustic Wave Resonators: from Continuum Mechanics Modeling to mm-Wave Operation

Acoustic waves have much shorter wavelength than electromagnetic waves. As such, acoustic wave resonators are compact in size, enabling miniature frontend filters integrated in cellphone frontends. New bands at higher frequencies are intended for supporting many more users. Advancement in resonators is called for in order to support filters at mm-wave frequencies. Ferroelectric materials with switchable polarization support new functionalities in acoustic wave resonators. In this talk, two original contributions are presented in the context of ferroelectric bulk acoustic wave resonators. In the first work, an equivalent circuit model is derived based on the continuum mechanics of ferroelectric materials. The new equivalent circuit model replaces the piezoelectric linear coupling between the electric and acoustic domains with the nonlinear coupling present in ferroelectric materials. The model is validated with measured impedance response of an intrinsically switchable Barium Strontium Titanate (BST) resonator at 2 GHz. In the second work, the design, fabrication, and measurements of a new trilayer AlN/ScAlN/AlN periodically poled film bulk acoustic resonator (FBAR) at 56 GHz are presented.

Wenhao Peng received the M.S. degree in ECE from the University of Michigan, in 2019, and the M.S.E. degree in ME from the University of Michigan, in 2024, where he is currently pursuing the Ph.D. degree in electrical and computer engineering. His research interests include designing and modeling acoustic wave resonators driven by thin-film piezoelectric and ferroelectric materials for applications in frontend filters and developing fabrication technologies for resonant MEMS devices.

Organizer: John Le
Faculty Advisor: Anthony Grbic