Enhanced quality factor in 2d nems resonators by optimizing air damping and thermoelastic damping

We achieve an improved quality (Q) factor in a two-dimensional (2D) molybdenum disulfide (MoS2) nanomechanical resonator at room temperature, by reducing air damping (Q(Air)(-1)) and thermoelastic damping (Q(TED)(-1)). We experimentally demonstrate that by reducing the vacuum pressure from 1.5x10(-1) Torr to 3.7x10(-4) Torr, the energy dissipation can be significantly reduced. Then from the gate tuning model of thermoelastic damping, we find that for these circular membrane resonators, smaller DC gate voltage V-GS and AC drive v(RF) generally lead to a higher Q factor. Furthermore, under high vacuum, the device exhibits a broader Q factor tuning range with the same range of V-GS and v(RF). By combining the high vacuum with low electrical drive, we increase the Q factor up to 1,772. We validate the tuning of Q factor through measurements on two different MoS2 resonators under varying vacuum pressures and electrical drives, and observe similar Q factor tuning trends. Such results are important for optimizing the Q factor in 2D nanomechanical resonators.