In situ thermal oxidation kinetics in few layer MoS2

It is important to understand the thermal and chemical stability of mono- and few-layer MoS2 for their use in applications. Oxidative environments are of particular interest due to the potential for use of MoS2 in electronics, sensing and energy storage. Here we present an in situ study of the oxidation kinetics of few-layer MoS2 over a wide range of temperatures. In situ monitoring of the MoS2 Raman spectra during oxidation revealed a decrease in the intensity of peaks following sigmoidal decay kinetics, which was initiated at temperatures as low as 300 °C. Ex situ resonance Raman spectroscopy, scanning electron and atomic force microscopy analysis indicated breaking up and thinning of the MoS2 films down to p-doped mono- and bi-layer regions. From analysis of the temperature-dependent decay rates and resonance Raman spectroscopy, we correlate oxidation rates to structural defects in the MoS2 films, and find a reaction energy of 0.54 ± 0.14 eV for the oxidation process.