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 (MoS
2
) nanomechanical resonator at room temperature, by reducing air damping $\left( {{Q_{{\text{Air}}}}^{ - 1}} \right)$ and thermoelastic damping $\left( {{Q_{{\text{TED}}}}^{ - 1}} \right)$. We experimentally demonstrate that by reducing the vacuum pressure from 1.5×10
^-1
Torr to 3.7×10
^-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 MoS
2
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.