Micro-Raman spectroscopy of graphene defects and tracing the oxidation process caused by UV exposure

Abstract

Raman spectroscopy is a widely used method for the analysis of various samples, including carbon-based materials. This study aimed to identify the number of layers and defects in graphene using micro-Raman spectroscopy. More specifically, this study examined the oxidation process of graphene under UV exposure. An investigation of the effect of the power density of the Raman excitation laser revealed a linear dependence between the ratio of I_2D/I_G and the power density of the excitation laser. Additionally, the absence of peak D due to the increase in power density provides evidence for the nondestructive nature of micro-Raman spectroscopy. Given the value of I_2D/I_G, one of the parameters for determining the number of layers in graphene, which reaches 1.39 at the edge, the findings indicate the possibility of an edge fold of single-layer graphene. During the oxidation process, the intensity and position of the D peak increase as a function of exposure time. Alterations in the graphene Raman spectrum, comprising the disappearance of the 2D peak and the appearance of the D peak, trace and confirm the oxidation process of the sample.