Reversibility of defect formation during oxygen-assisted electron-beam-induced etching of graphene

We explore the defect formation on single-layer graphene partially suspended over a microcavity upon etching by a focused electron beam in a reactive oxygen atmosphere. The formation of oxygenated defects in an area of several m(2) around the cut is studied by Raman spectroscopy. The narrow symmetric Raman D band has the same bandwidth as the G band line width of supported graphene. For suspended graphene, the D bandwidth is larger. From the ratio of the intensity of the Raman D and D band (I-D/I-D), it is concluded that mainly sp(3)-type defects are formed on supported graphene and more defects with a different spectral signature are formed on suspended graphene. Annealing in reductive H-2/Ar atmosphere is found to remove bonded oxygen on supported graphene, whereas on suspended graphene with higher density of defects, defects are removed only partially.