Vertical Graphene By Plasma Enhanced Chemical Vapor Deposition: Correlation of Plasma Conditions and Growth Characterstics

Vertically aligned graphene was grown by plasma enhanced chemical vapor deposition using methane feedstock. Optical emission spectroscopy (OES) was used to monitor the plasma species and Raman spectroscopy was used for characterizing the properties of as-grown, vertically-aligned graphene. OES-derived information on plasma species such as C, C₂, CH, and H are correlated with the properties of the vertically-aligned graphene. Graphene grown at 250 W and 15 sccm exhibited the lowest amount of defects. While OES peak intensities occurred at the highest power and lowest flow conditions, the OES peak ratios of plasma species had a greater dependence on flow rate and exhibited a saddle point in the atomic C/H ratio corresponding to optimal growth involving the lowest amount of overall defects. Plasma diagnostics provide a valuable approach to optimize growth characteristics and material properties.