Carbon Structures Grown by Direct Current Microplasma: Diamonds, Single-Wall Nanotubes, and Graphene

Plasma assisted CVD is now an established technique for the growth of a variety of dielectrics and semiconductors. The versatility of an in-house developed direct-current (dc) microplasma deposition system is demonstrated here for the growth of a wide range of carbon-based materials. Diamond, nanodiamond, nanocrystalline graphite, single-wall carbon nanotubes, and few-layer graphene have been deposited using the same dc microplasma deposition system using 0.5% CH4/H2 gas feed, but changing only the substrate temperature (in the range 500−1150 °C) and the total pressure (0.3−200 Torr). The different structures have been characterized by scanning electron microscopy and micro-Raman spectroscopy. The experimental data have been interpreted from a thermodynamic point of view by applying a nonequilibrium nondissipative model. Nonequilibrium phase diagrams are presented and compared to the experimental data to provide a wide-ranging interpretation scenario.