Evidencing Dissipation Dilution in Large-Scale Arrays of Single-Layer WSe2 Mechanical Resonators

Abstract

Micromechanical resonators with very low mass are highly desirable for sensing and transduction applications. Layered materials (LMs) can be used to fabricate single- to few-atom thick suspended membranes, representing the ultimate limit to low mass. Transition-metal dichalcogenides (TMDs), such as WSe₂, are particularly compelling because they can host spatially confined excitons in single layer (1L), potentially enabling the creation of nonclassical mechanical states and interconnects between quantum networks and processors. However, these exciting prospects have been tempered by low device yields, invasive methods for detecting resonator motion, and high mechanical damping. Here, we report the creation of mechanical resonators by suspending 1L-WSe₂ across a 90 × 90 array of 2.5-μm diameter holes with a > 75% success rate. We detect the resonator room-temperature (RT) Brownian motion and measure resonator mass to quantify contamination, using below-bandgap laser interferometry. We investigate the relation between frequency, diameter, and mechanical quality factor, which can exceed 1000 in our devices. We find the dependence agrees with the effect of dissipation dilution, highlighting the importance of reducing mechanical mode-bending. Key to this is the large-scale, high-quality arrays that make it possible to access a frequency range that surpasses previous works. Further, the ability to fabricate large numbers of 1L resonators, and the simplicity of probing their motion without electrodes or an underlying reflective substrate, facilitates previously hard-to-reach configurations, such as resonators in phononic crystals or within optical cavities.