Calibrating temperature coefficient of frequency (TCf) and thermal expansion coefficient (α) of MoS2 nanomechanical resonators

We report on experimental study and calibration of temperature coefficient of frequency (TCf) and laser heating effect in two-dimensional (2D) resonators, and through which, a new method for determining thermal expansion coefficient (α) in 2D crystals. We measure the resonance characteristics of the `drumhead´ nanomechanical resonators based on molybdenum disulfide (MoS₂) using sensitive laser interferometry. By tracking the resonance frequency at varying temperatures, we obtain high TCf up to -0.396%/K. Combining with finite element modeling (FEM), we extract α of 3.7-4ppm/K. We also measure the laser power dependence of the resonance frequency (up to -4.116%/mW), demonstrating the potential of this type of devices for sensitive thermometers and laser power meters.