Effect of gamma irradiation on the physical properties of MoS₂ monolayer

Two-dimensional transition metal dichalcogenides (2D-TMDs) have been proposed as novel optoelectronic materials for space applications due to their relatively light weight. MoS₂ has been shown to have excellent semiconducting and photonic properties. Although the strong interaction of ionizing gamma radiation with bulk materials has been demonstrated, understanding its effect on atomically thin materials has scarcely been investigated. Here, we report the effect of gamma irradiation on the structural and electronic properties of a monolayer of MoS₂. We perform Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) studies of MoS₂, before and after gamma ray irradiation with varying doses and density functional theory (DFT) calculations. The Raman spectra and XPS results demonstrate that point defects dominate after the gamma irradiation of MoS₂. DFT calculations elucidate the electronic properties of MoS₂ before and after irradiation. Our work makes several contributions to the field of 2D materials research. First, our study of the electronic density of states and the electronic properties of a MoS₂ monolayer irradiated by gamma rays sheds light on the properties of a MoS₂ monolayer under gamma irradiation. Second, our study confirms that point defects are formed as a result of gamma irradiation. And third, our DFT calculations qualitatively suggest that the conductivity of the MoS₂ monolayer may increase after gamma irradiation due to the creation of additional defect states.