Nanoelectromechanical Memories Based on Nonlinear 2D MoS2 Resonators

We report on the first nanoelectromechanical memories based on two-dimensional (2D) molybdenum disulfide (MoS
2
) resonators with Duffing nonlinearity. The local-gate Mos
2
resonators show spring hardening at large drive amplitude, and the unstable solution leads to a resonance response that is related to the direction of frequency sweep. Such frequency hysteresis further results in a nanomechanical memory: by choosing the reference frequency
$(f_{\text{ref}})$
to be within the frequency range of unstable solution
$(\Delta f)$
, the responses at
$f_{\text{ref}}$
under upward and downward frequency sweeps show clear difference in amplitude, forming a novel memory based on 2D nanoelectromechanical systems (NEMS). We experimentally demonstrate circular “drumhead” 2D Mos
2
Nems resonators with capacitive driving using the local gate electrodes and optical detection, which shows excellent memory characteristics. These devices work robustly without a bit error during 50 cycles of voltage pulses, with a tuned on/off ratio by setting the
$f_{\text{ref}}$
position. These memories based on 2D NEMS resonators establish the foundation for more complex NEMS logic and memory circuits based on individually-addressable 2D NEMS resonators, towards a scaled, ultralow-power
$(\sim10^{-12}\ \mathrm{W})$
, fast and highly tunable integrated computing system based on resonant 2D membranes.