Atomically Thin WS2 Nanomechanical Resonators with Geometry-Engineered Flexural Rigidity Control

Abstract Two-dimensional (2D) materials have emerged as promising platforms for nanoelectromechanical systems (NEMS), optomechanics, and strain-engineered devices thanks to their outstanding elasticity and strength even down to atomic thinness. However, scalable engineering and control of the mechanical properties of 2D materials through structural design remains challenging. Here, we demonstrate effective flexural rigidity enhancement of atomically thin WS2 nanomechanical resonators by three-dimensional (3D) structuring of corrugations in 2D films. WS2 resonators are fabricated using focused ion beam (FIB) milling with customizable corrugations consisting of ∼500 nm-wide domes with heights from 60 to 130 nm. Optomechanical resonance measurements reveal substantial stiffness enhancement induced by the corrugated geometry. Combined with analytical and numerical modeling, our measurements show up to 144-fold enhancement in effective flexural rigidity, depending on corrugation geometry and boundary conditions. These results establish 3D molding as an effective strategy toward engineering and controlling mechanical properties of 2D materials and their devices.