Aromatic molecules doping in single-layer graphene probed by Raman spectroscopy and electrostatic force microscopy

Electrostatic force microscopy (EFM) and Raman spectroscopy are used to study the effects of aromatic molecules on the doping level of single layer graphene (SLG). The EFM results demonstrate that the aromatic molecules with electron-donating group (n-doping) decrease the surface potential of the SLG films, while the molecules with electron-withdrawing groups (n-doping) increase their surface potential. Meanwhile, Raman spectra indicate that the aromatic molecules with electron-withdrawing groups make the SLG p-dope and upshifts in both Raman G and 2D frequencies. While the aromatic molecules with electron-donating groups n-dope the SLG and up-shift the 2D-but down-shift the G-band frequencies.