Etching processes of transferred and non-transferred multi-layer graphene in the presence of extreme UV, H₂O and H₂

In this work we expose transferred multi-layer graphene (i.e. graphene separated from the substrate used for graphene growth and placed onto a carrier sample) to Extreme Ultraviolet light and water, in the presence of hydrogen. It is observed that graphene oxidizes by breaking down its aromatic structure into the enol form of 1,3-diketone. Furthermore, this oxidation is compared with studies on as-grown multi-layer graphene samples, which are shown to not oxidize. Our work shows that oxidation is most likely limited to a few layers of graphene at the interface between the graphene and the substrate onto which it is transferred. This is attributed to the presence of water, trapped during the transfer process, which is dissociated by secondary electrons from the substrate.