The structural and electrical evolution of chemical vapor deposition grown graphene by electron beam irradiation induced disorder

Abstract

The defect formation mechanism in chemical vapor deposition grown single layer graph ene devices has been investigated by increasing electron beam (e-beam) irradiation doses gradually up to 750 e /nm2 . The evolution of D peaks in Raman spectra provides an evi dence of strong lattice disorder due to e-beam irradiation. Particularly, the trajectory of D and G peak intensities ratio (ID/IG) suggests that the transformation of graphene from crys talline to the nanocrystalline and then towards amorphous form with increasing irradia tion dose. The defect parameters were calculated by phenomenological model of amorphization trajectory for graphitic materials. The mobility decreasing gradually from 1200 to 80 cm2 /V s with gradual increase of irradiation dose, which implies the forma tion of localized states in e-beam irradiated graphene. The Dirac point is shifted towards negative gate voltage which indicates the n-doping in graphene with increasing e-beam irradiation dose.