Persistent resonance frequency shift of MoS2 mechanical resonator by laser irradiation

We investigate the persistent photoconductivity effects on MoS
2
mechanical resonator toward high performance of optically tuned nano-electro-mechanical systems. After the laser irradiation, the resonance frequency of the resonator shifted downward over than 20 minutes, which is induced by not photothermal effects but persistent photoconductivity effects. In our case, the origin of persistent photoconductivity is most likely due to the trapped photogenerated holes at defects or contaminations on MoS
2
. The trapped holes induce softening effects on electrostatic force between mechanical resonator and the substrate, which decreases resonance frequency.