Mega-electron-volt proton irradiation on supported and suspended graphene: A Raman spectroscopic layer dependent study

Abstract

Graphene samples with 1, 2, and 4 layers and 1 + 1 folded bi-layers and graphite have been irradiated with 2 MeV protons at fluences ranging from 1 × 1015 to 6 × 1018 ions/cm2. The samples were characterized using visible and UV Raman spectroscopy and Raman microscopy. The ion-induced defects were found to decrease with increasing number of layers. Graphene samples suspended over etched holes in SiO 2 have been fabricated and used to investigate the influence of the substrate SiO2 for defect creation in graphene. While Raman vibrational modes at 1460 cm-1 and 1555 cm-1 have been observed in the visible Raman spectra of substantially damaged graphene samples, these modes were absent in the irradiated-suspended monolayer graphene. © 2011 American Institute of Physics.