Observation of nanocarbon-growth transition from 1D to 2D morphology through on-naked-insulator plasma processing

Direct growth of graphene among nanocarbons on catalyst- and seed-free insulators, which offers a technical advance in methodologically straightforward simplicity and avoiding the post-growth transfer process, has been extensively investigated toward evolving a wide range of applications. In this study, plasma-enhanced chemical vapor deposition (PECVD) instead of thermal CVD (TCVD) is adopted for lowering the on-insulator growth temperature and gaining new insight into the fundamental growth-process of 2D graphene in connection with 1D single-walled carbon nanotubes (SWNTs). It is found for the first time that PECVD of low-influx plasmas and-energy ions facing an insulating growth-substrate of naked quartz glass enables SWNTs, single-layer graphene (sGPN), and a few-layers graphene (fGPN) to grow at critical ambient temperature of 700 ℃, where an equilibrium state is sophisticatedly maintained between carbon-source deposition and etching of unwanted materials. This temperature is substantially lower than 1100-1600 ℃ in the cases of TCVD so far. Furthermore, when the plasma influx and ion energy is gradually increased at the same temperature, only the 2D nanocarbon composed of sGPN and turbostratic graphite in the form of a mixture isobserved to grow while SWNTs and fGPN disappear.