Dissipation and Loss Angle in Two-Dimensional Molybdenum Ditelluride Nanoelectromechanical Resonators

We report on the measurements of strain-tunable dissipation properties and the extraction of loss angle in two-dimensional (2D) molybdenum ditelluride (MoTe
2
) nanoelectromechanical resonators, for the first time. We experimentally demonstrate that for fully-clamped resonant 2D MoTe
2
nanoelectromechanical systems (NEMS), the quality factor (Q) can be tuned by ΔQ/Q = 90.7% from 323 to 616 using DC gate voltages (V
GS
) for the fundamental flexural mode, and can be tuned by ΔQ/Q = 148%, from 230 to 570 for the second mode. We develop an accurate strain-modulated dissipation model to extract the elongational loss angle (δ
elong
) of 0.05 for MoTe
2
, which has not been demonstrated previously. We then measure the Q at varying AC driving voltages (v
g
), which shows that Q is tuned from 248 to 325, with ΔQ/Q = 31%. By fitting to the dissipation model, we find that the extracted δ
elong
is consistent with the result obtained by varying V
GS
, showing that δ
elong
can be reliably extracted from the Q tuning. This work provides important guidelines for extracting important material parameters, and for tuning the dissipation properties of 2D NEMS resonators.