Tuning Strain and Quality Factor of 2D MoS2 NEMS Resonators using Annealing and Electrostatic Gating

SummaryWe develop a technique for wide-range tuning of strain and quality (Q) factor in resonant two-dimensional (2D) molybdenum disulfide (MoS
2
) nanoelectromechanical systems (NEMS), by using thermal annealing combined with electrostatic gating. The initial strains of three fully-clamped circular MoS
2
NEMS resonators are released by a thermal annealing process, and their resonances under different DC gate voltages (V
GS
) before and after annealing are measured. We find that the annealed devices have smaller initial strains, corresponding to smaller eigenfrequencies and wider frequency tuning ranges. We further extract the Q for these MoS
2
resonators before and after annealing. The results show that Q increases with V
GS
in both the annealed and non-annealed cases, and the annealed devices have a smaller initial Q and a larger Q tuning range. By varying V
GS
, we can tune the Q for fully-clamped resonators by ΔQ/Q = 528.3% before annealing and by ΔQ/Q = 891.7% after annealing. This strain dependence of Q is important for optimizing sensitivity, dynamic range, and signal transduction efficiency of 2D NEMS resonators towards ultralow-power, ultra-sensitive and frequency-selective devices for sensing, memory, computing, and signal processing.