Two-dimensional MoS2 nanomechanical resonators freelysuspended on microtrenches on flexible substrate

This digest paper reports on the first high-frequency nanomechanical resonators based on molybdenum disulfide (MoS₂) crystalline flakes freely-suspended on microtrenches (~13μm wide and 14μm deep) fabricated on flexible substrate, with bendability and stretchability. Through investigations of the device resonances via optical excitation and detection by ultrasensitive laser interferometry, we first observe multimode resonances up to ~50MHz with the polydimethylsiloxane (PDMS) substrate under different bending and stretching conditions. The device resonance frequencies (f_res) first increase and then stabilize while quality (Q) factors are enhanced with PDMS trench widening of up to 161% in the region away from the MoS₂ flake and 61% at the MoS₂ flake edge, without breaking the device. This platform could facilitate investigations of the strain limits in devices, strain-induced bandgap tuning in two-dimensional (2D) crystals, and strain-engineered performance enhancement (e.g., f_res, Q, and mobility) in 2D resonators. Furthermore, it is well suited for exploring new 2D flexible and wearable electronic components such as strain gauges and resonant transducers.