▎ 摘　　要

The defect formation mechanism in chemical vapor deposition grown single layer graphene devices has been investigated by increasing electron beam (e-beam) irradiation doses gradually up to 750 e(-)/nm(2). The evolution of D peaks in Raman spectra provides an evidence of strong lattice disorder due to e-beam irradiation. Particularly, the trajectory of D and G peak intensities ratio (I-D/I-G) suggests that the transformation of graphene from crystalline to the nanocrystalline and then towards amorphous form with increasing irradiation dose. The defect parameters were calculated by phenomenological model of amorphization trajectory for graphitic materials. The mobility decreasing gradually from similar to 1200 to similar to 80 cm(2)/V s with gradual increase of irradiation dose, which implies the formation 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. (C) 2013 Elsevier Ltd. All rights reserved.