Synthesis of graphene together with undesired CuxO nanodots on copper foils by low-pressure chemical vapor deposition

•Composite film composed of graphene and CuxO nanodots is fabricated on Cu foil.•The composition and the quality of the films were tuned by controlling growth parameters.•Single layer graphene obtained.

The synthesis of graphene on Cu foils has been carried out using a low-pressure chemical vapor deposition (LPCVD) process. Under certain growth conditions apart from the graphene flakes, undesired CuxO nanodots appear. The samples were characterized by scanning electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray photoemission spectroscopy. On the basis of the results, we investigated the effect of growth parameters such as pressure, methane-to-hydrogen ratio and cooling atmosphere on the growth rate, the composition, especially the cleanliness of graphene by scanning electron microscopy in detail. It is shown that the obtained film is quite sensitive on the preparation conditions and the appearance of CuxO nanodots is preventable.