The Amorphization of Monolayer MoS2 Induced by Strong Oxygen Plasma Treatment

Abstract

By strong oxygen plasma treatment on monolayer MoS₂, we observe the disappearance of the Raman modes of MoS₂. We propose the hypothesis that the state of MoS₂ translates from crystal to amorphous after strong oxygen plasma treatment. The evidences of no MoO₃ formation shown by Raman spectra and the appearance of the Mo6+ peak and decreased O concentration shown by X-ray photoelectron spectroscopy support our hypothesis. The amorphization of monolayer MoS₂ is further confirmed by the quenching of photoluminescence (PL) and the disappearance of two absorption peaks related to A, B exciton which demonstrates the disordered bandgap. Finally, we found that the amorphous MoS₂ can improve the absorption fraction at the visible light (500~ 750 nm) which is potential for future visible light photocatalysis.