Effects of γ-ray radiation on two-dimensional molybdenum disulfide (MoS₂) nanomechanical resonators

We report on experimental investigation and analysis of γ-ray radiation effects on two-dimensional molybdenum disulfide (MoS₂) drumhead nanomechanical resonators vibrating at megahertz frequencies. Given calibrated dosages of γ-ray radiation of ∼5000 photons with energy at 662 keV, upon exposure over 24 or 12 h, all the MoS₂ resonators exhibit ∼0.5–2.1% resonance frequency upshifts due to the ionizing γ-ray induced charges and their interactions. The devices show γ-ray photon responsivity of ∼30–82 Hz/photon, with an intrinsic γ-ray sensitivity (limit of detection) estimated to approach ∼0.02–0.05 photon. After exposure expires, resonance frequencies return to an ordinary tendency where the frequency variations are dominated by long-term drift. These γ-ray radiation induced frequency shifts are distinctive from those due to pressure variation or surface adsorption mechanisms. The measurements and analyses show that MoS₂ resonators are robust yet sensitive to very low dosage γ-ray, demonstrating a potential for ultrasensitive detection and early alarm of radiation in the very low dosage regime