Low dissipative mechanical resonators based on WSe$_{\mathrm{2}}$ monolayers

Atomically thin nano-electromechanical systems (2D-NEMS) combine low mass resonators having resonant frequencies in the MHz-GHz range, wide tunability and low damping. Atomically thin 2D semi-conductors, such as transition metal dichalcogenides (TMD), have rich optical properties (direct band gap, spin valley, embedded quantum emitters\textellipsis ), which are linked to their low dimensionality. While optical and electronic properties of WSe$_{\mathrm{2}}$ have been intensively investigated, there have not been any studies on WSe$_{\mathrm{2}}$ mechanical resonators. Although TMD NEMs have been fabricated, they have not been measured at cryogenic temperature so far. I will present a new semiconductor 2D-NEMS made of a single layer of WSe$_{\mathrm{2}}$. We measured mechanical and photoluminescence spectra of WSe$_{\mathrm{2}}$ suspended drums at cryogenic temperatures. Our results demonstrate an extremely low damping at low temperature with a quality factor Q \textgreater 47000 at T$=$3K, which is higher than what can be achieved with graphene NEMs. In addition, we investigated photothermal and optoelectronic effects on the mechanical degree of freedom, revealing the high potential of semiconductor 2D-NEMS for optomechanics experiments.