Dependence of plasma power for direct synthesis of nitrogen-doped graphene films on glass by plasma-assisted hot filament chemical vapor deposition

Metal-free synthesis of nitrogen-doped (N-doped) graphene films on glass is important for modulating the properties of graphene glass but has so far met with limited success. In this study, direct synthesis of N-doped graphene films on glass with eco-friendly N₂ dopant through a novel plasma-assisted hot filament chemical vapor deposition (HFCVD) approach was reported. Influence of plasma power on the structural and electrical properties of N-doped graphene films was investigated. The filament and plasma source were found to be both crucial for depositing high-quality N-doped graphene films with N₂ dopant. With a small N₂ flow of 5 sccm, the N content of graphene films synthesized by plasma-assisted HFCVD could be modulated from 0.6 to 3.0 at.% through adjusting the plasma power from 0 to 130 W. A lowest resistivity of 4.68 × 10⁻³ Ω cm was obtained at 130 W. Temperature-dependence of resistance measurement revealed that the carrier mobility of N-doped graphene films decreased by raising the plasma power, which was attributed to the increase of conductive activation energy. This work provides an alternative method for direct, controllable and green preparation of N-doped graphene films on glass.