Single crystalline 4H-polytype silicon carbide microresonator sensor for mass detection

In this paper, the mass detection capability of microresonator sensors formed on a wide bandgap semiconductor material platform - single crystalline 4H-polytype silicon carbide (4H-SiC) was investigated. Microresonators in the cantilever configuration were fabricated on a 4H-SiC substrate and a dynamic vibration method was applied to characterize the resonant frequency and its shift with the point mass added at the cantilever tip by focused ion beam induced platinum (Pt) deposition. As experimental results show, a mass sensitivity of 799.3 Hz/pg (1.25 fg/Hz) was demonstrated by cantilevers of 80 μm×2.9 μm×1 μm in size. The linear dependence of frequency shift with added Pt mass and sensitivity data agree very well with an analytical model. This mass sensing capability together with the superior chemical, biological and mechanical properties of single crystal 4H-SiC material makes 4H-SiC microresonator sensor very promising for chemical sensing and bio-sensing.