Visualizing oxidation in monolayer 1T′-MoTe2

Abstract The susceptibility to oxidation of two-dimensional materials such as black phosphorus and molybdenum ditelluride hampers their utilization. Commonly used means for monitoring the oxidation process, including x-ray photoelectron spectroscopy and Raman spectroscopy, are time-consuming and expensive. In this work, a rapid and affordable method for characterizing oxidation based on optical microscopy is presented. The change in contrast of monolayer 1T′-MoTe 2 in different color channels during oxidation is tracked by optical microscopy and the relationship between contrast and the Raman B g peak intensity is established, visualizing oxidation in monolayer 1T′-MoTe 2 . The changes in optical contrast are explained by a three-layer model based on the Fresnel formula. The results also offer guidance for visualizing the oxidation of two-dimensional materials on different substrates. This method will be of significant value in both fundamental research and large-scale production.