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/H-2 gas feed, but changing only the substrate temperature (in the range 5001150 degrees C) and the total pressure (0.3200 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.