Methyl monolayers suppress mechanical energy dissipation in micromechanical silicon resonators

Abstract

The quality factor and long-term stability of megahertz-range micromechanical silicon resonators can be significantly improved by a methyl monolayer directly bonded to the silicon surface. Mechanical energy dissipation in functionalized resonators is shown to be a sensitive function of surface chemistry. At least 18% and 41% of the dissipation in H-terminated and long-chain alkyl-terminated resonators, respectively, is surface related. Surface-induced dissipation is poorly correlated with the mechanical properties of the terminating layer, but may be related to the surface defect density.