Characterizing the resonant behavior and quality factors of 3C-SiC diaphragms using frequency analysis and the ring-down technique

This paper reports the findings of a study to characterize the resonant behavior of high-aspect ratio, NEMS-scale 3C-SiC diaphragms. The diaphragms consisted of single crystalline 3C-SiC films that were grown by APCVD and created by Si bulk micromachining. The diaphragms were excited into resonance under vacuum and assessed using optical interferometry. Over 40 resonant peaks were observed for a 250 nm-thick, 1 × 1 mm² diaphragm for frequencies up to 2.5 MHz. The frequency-to-bandwidth ratio method and the ring-down technique were used to assess the quality factor for several prominent peaks. Although the fundamental mode exhibited a quality factor of ~3000, all other modes had Q's of > 10,000, with the highest being ~190,000 for the (2, 3) mode.