Fabrication of single-crystal silicon carbide MEMS/NEMS for bio-sensing and harsh environments

A conductivity-selective photoelectrochemical etching process was reported to fabrication single-crystal SiC micro/nanoelectromechanical structures. When a bias employing the different flatband potentials of n-type and p-type SiC in the KOH solution was applied, p-SiC suspended micro and nanostructures were released by undercutting the underlying n-SiC substrate. The etching of n-SiC was promoted by more upward bending of the energy band due to the applied bias, while the etching of p-SiC was suppressed by preserving downward band-bending. The Young´s modulus (E₀=530 GPa) of single-crystal SiC was extracted experimentally and the resonant frequency (f₀=11.5 MHz) of a cantilever was derived.