Research on Dissipation Dilution Mechanism and Boundary Dissipation Suppression Technique for High-Stress Graphene Nanoelectromechanical Resonator

Abstract

The low-quality factor is a key bottleneck for the engineering and commercial application of graphene nanoelectromechanical resonators at room temperature. The hypothesis in dissipation dominated by the ohmic loss is difficult to cover this phenomenon. Mechanical loss may still be on the list of the main causes for the quality factor stress-modulation characteristics of graphene resonators. The dissipation dilution theory reveals the intrinsic energy and dissipation mechanism of the traditional high-stress silicon-based resonator, which may also be applied to two-dimensional (2D) materials if dominated by mechanical loss. Based on Zener’s model of anelasticity, combined with the edge-corrected mode shape, the stress dilution mechanism of the bending potential dissipation of the graphene resonator is revealed. On this basis, the resonator dissipation is decomposed into boundary dissipation and non-boundary dissipation parts, and the steep rise phenomenon of the bending dissipation density (curvature) in the boundary region is analyzed through theoretical calculation. The analysis reveals that boundary dissipation is dominant in bending dissipation. To effectively suppress the boundary dissipation, a novel design of a graphene resonator via soft-clamped phononic crystal (PnC) is proposed. The existence of localized mode (LM) and effective suppression of boundary dissipation are verified in the simulations of both triangular and honeycomb PnC lattices. The theoretical model developed in this paper provides a new window into the dissipation properties of graphene nanoelectromechanical resonators, and the design of graphene resonators via soft-clamped PnC is expected to provide a new route toward high-quality factors at room temperature.