Optimisation of quality-factor for in-plane free-free nanoelectromechanical resonators

The performance of nanoelectromechanical (NEM) resonators is destructively affected by mechanical damping that requires more careful designs of the resonators, along with the improvement of their working environments to be overcome. In this Letter, various sources of damping are studied theoretically for the in-plane clamped-clamped (CC) NEM resonator and compared with the equivalent values for the designed alternative free-free (FF) resonator. The in-plane FF NEM resonator shows higher quality factor compared with its CC counterpart, that is about four orders of magnitude higher for the vacuum- and low temperature-working environments and a six times larger value for the working environment of air and room temperature based on the numerical results. The successful fabrication of the FF NEM resonator proves the feasibility of fabrication for the structure with the presented design. The authors show that by optimising the position of the support beams of the FF NEM resonator, the anchor dissipation, that is, the main restrictive source on the total quality factor for the vacuum- and low temperature-working environments, is minimised to its smallest value.