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.

Plasma Processing and Treatment of 2D Transition Metal Dichalcogenides: Tuning Properties and Defect Engineering

“…Plasma treatment can also change the morphology of 2D materials through various phenomena such as amorphization, reshaping the platelets, layer decoupling, particle formation, and reducing particle size. Dhall et al , have employed mild O 2 plasma to increase the van der Waals distance between MoS 2 layers without structural damages or layer etching.…”