High-frequency SiC microdisk resonators operating in water with responses to H2O2 and NH4OH

This digest paper describes experimental demonstration of high-frequency silicon carbide (SiC) microdisk resonators operating in aquatic environments, including water and water solutions of H₂O₂ and NH₄OH. We demonstrate, for the first time, that center-clamped circular SiC microdisks can preserve multiple robust flexural-mode resonances in water. We have observed strong multimode responses in the SiC microdisks, up to more than a dozen resonance modes, with resonance frequencies up to ~120MHz and quality (Q) factors up to ~800 in air, and up to 9 resonances in the range of 1-120MHz with Qs up to ~35 in water. Both the number of modes and the Q values are the highest among reported flexur-al-mode resonators measure in water. We also explore how geometrically defected microdisks in an `eclipsed moon´ structure are affected, by comparing their multimode resonance characteristics to those of the `full moon´ structures. We further demonstrate the operations of the SiC microdisk resonators in hydrogen peroxide (H₂O₂) and ammonium hydroxide (NH₄OH) solutions, and by examining 2 resonance modes, we have observed linear relationship between the frequency shift and the solution mass density, in both modes.