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.