Raman investigation of laser-induced structural defects of graphite oxide films

¹ Dipartimento di Science Matematiche ed Informatiche, Scienze Fisiche e Scienze della Terra, Università di Messina, Viale F. Stagno d’Alcontres 31, S. Agata, 98166 Messina, Italy.
² Nuclear Physics Institute, CAS, 25068 Rez, Czech Republic.

^* Corresponding authors: gdangelo@unime.it, vromano@unime.it

Published online: 9 January 2018

Abstract

Since the beginning of intensive studies on graphene and graphitic materials, Raman spectroscopy has always been used as a characterisation technique. This is due to two main reasons: the non-destructive nature of this experimental technique and its ability to distinguish between the plethora of existing carbon materials. One of the most challenging research activities concerns the production of graphene microcircuits. To address this issue, a possible strategy is to directly reduce and pattern graphite oxide (GO) film by laser irradiation. The objective of this study is to evaluate the laser irradiation-induced structural changes on thin GO films by using Micro-Raman spectroscopy. We used as a source a Nd:YAG laser (1064 nm) and different laser fluences: 15 J/cm², 7.5 J/cm² and 5 J/cm². We have analyzed the modifications of the main Raman contributions of these graphitic materials: the D band (defect induced band), the G band (band due to sp² hybridized carbon atoms) and the 2D band (D band overtone). In particular, we found out that our figure of merit (FOM) parameters, i.e. the intensity ratio I_D/I_G (for the D band and G band) and I_2D/I_G (for the 2D band and G band), change with the laser fluences, revealing a different effect induced by the laser irradiation. The best results are found in the sample irradiated with 5 J/cm², suggesting that higher fluences do not lead to better results.