Catalyst-free Growth Mechanism and Structure of Graphene-like Nanosheets Formed by Hot-Filament CVD

We report on a simple and effective method of synthesizing graphene‐like nanosheets on silicon substrates pre‐deposited with a carbon film or carbon nanodots in hot‐filament(HF)CVD from a methane precursor. The results of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and micro‐Raman spectroscopy (RS) indicate that the structure of graphene‐like nanosheets is changed with the flow rate change of methane and the pretreatment of the substrate surface. The catalyst‐free growth of graphene‐like nanosheets is related to the diffusion and assembly of carbon atoms on the substrate surface and the separation of graphene‐like nanosheets from the substrate surface. Graphene‐like nanosheets free of catalyst are grown on silicon substrates in a hot‐filament (HF)CVD system, in which the silicon substrates are deposited with carbon film and nanodots by plasma‐enhanced HFCVD. During the growth of graphene‐like nanosheets, methane, with flow rates of 20, 50, and 70 sccm, is employed to synthesize the graphene‐like nanosheets.