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

TL;DR

This study uses micro-Raman spectroscopy to analyze graphene defects, determine layer number, and trace oxidation caused by UV exposure, revealing non-destructive measurement and oxidation progression through spectral changes.

Contribution

It demonstrates the application of micro-Raman spectroscopy for non-destructive analysis of graphene defects, layer identification, and oxidation tracking under UV exposure.

Findings

Linear dependence of I2D/IG ratio on laser power density

Absence of D peak at high power indicates non-destructive measurement

Increase in D peak intensity and shift during oxidation confirms oxidation process

Abstract

Raman spectroscopy is one of the widely used methods in 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, the study examined tracing the oxidation process of graphene under UV exposure. Investigation of the effect of the power density of the Raman excitation laser reveals a linear dependence between the ratio of I2D/IG and the power density of the excitation laser. Also, the absence of peak D due to the increase in power density provides evidence for the non-destructive nature of micro-Raman spectroscopy. Given the value of I2D/IG, one of the parameters for determining the number of layers in graphene which has reached 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.