부산대학교 도서관

We studied the low energy (5.4 keV) He + ion irradiation effect on the properties of chemical vapor deposited graphene transferred onto SiO 2 /Si substrate. For a small dose density of 4 × 1012 He + /cm2, both the G and 2D bands in the Raman spectra exhibit blue-shift and the intensity ratio of the 2D and G peaks decreases. The intensity ratio of the D and G peaks increases a lot as the dose density is larger than 1.2 × 10 13 He + /cm 2 . It suggests that before the formation of large amount of defects, low energy He + ion irradiation may induce charge-transfer doping in graphene due to the presence of polymer residues. Broad spatial distributions of the band shift and the intensity ratio indicate inhomogeneity of doping level in graphene.