Resonance Raman spectroscopy of MoS2 monolayers treated with nitrogen plasma

The creation of defects in two-dimensional (2D) materials is crucial for tuning their optical and electrical properties. Molybdenum disulfide is the most promising 2D material, with applications ranging from optoelectronics to high-performance Li-S batteries. Hence, it is possible to tune its properties for desirable applications by introducing defects into the monolayer structure. In this study the presence of defects is probed by resonance Raman spectroscopy The results show that the Raman spectra of the MoS2 monolayers gradually change as the nitrogen plasma treatment time increases. The changes in the longitudinal acoustic LA(M) intensity, and second-order 2LA(M), and 2LA(K) intensity and full width at half maximum variations observed in the resonance Raman spectra were used as figures of merit to characterize the MoS2 samples with respect to the density of defects. Photoluminescence spectroscopy and atomic force microscopy were used to characterize the samples.