Radio-frequency multi-mode micromechanical disk resonators in 500nm thin silicon carbide (SiC)

Abstract

We report on experimental demonstration of a new type of radio-frequency (RF) multi-mode micromechanical resonators based upon vibrating circular disks made of a 500nm thin SiC epilayer grown on single crystal Si. These center-clamped microdisk resonators offer multiple flexural-mode resonances at RF/microwave frequencies, depending on both disk and anchor diameters. We show that simply changing the anchor size can already tune the interesting patterns of the multi-mode frequency spectra. A ∼40μm-diameter SiC disk with a slender (∼800nm) anchor exhibits more than a dozen flexural modes in ∼2-20MHz with typical quality factors Q's∼1000-4000. A disk with same dimensions but a wide (∼20μm) anchor has its first 9 flexural modes within 15-20MHz with Q's∼500-2500. The measurements and analyses show that the frequency spacing between the flexural modes, the splitting of degenerate modes, and their Q's (or dissipation), can all be tuned by engineering the size and shape of the anchor of a multi-mode flexural thin-film microdisk resonator.