Ion-beam irradiation effects on the structure and electronic properties of MoS₂

Abstract

In view of verifying the influence by defects on the structure and electronic properties, a monolayer MoS₂ irradiated with low energy Ar⁺ ion beam is evaluated. After Ar⁺ ion irradiation, both of the line widths of E_2g and A_1g peaks for Raman spectroscopy increase and become broader as increasing of irradiation time. It is mainly attributed to increasing of the contribution of the satellite peaks caused by the introduction of defects. Interestingly, the effect of the irradiation is more significant for E_2g in spite of less influence of charge transfer by molecular adsorption on which A_1g peak is much more sensitive due to its large electron-phonon coupling. As increasing of the irradiation time, the intensity of the peak around 1.86 eV in photoluminescence (PL) decreases significantly with the emerging of a tail at the lower energy side, and the peak around 1.35 eV assigned to the emission related to impurity levels also rapidly decreases upon ion beam irradiation.