Graphite Ion Source Geometry and Ne-Gas Pressure Dependent Growth and Morphology of Carbon Nanoclusters: AFM Analysis

The understanding of the growth and morphological evolution of nanoclusters with process parameters such as ion source geometry, voltage, current, time, and gas pressure are highly important to achieve their desired sizes, morphology, and concentration. Carbon nanoclusters (0-dimensional) were synthesized using the DC glow discharge technique at different process parameters (such as Ne-gas pressures, current, voltage, etc.) using custom fabricated graphite ion sources of cylindrical and U-shaped geometries. The morphology and density of carbon nanoclusters were studied with an atomic force microscope (AFM) to understand their evolution at different process parameters. The study suggests that the U-shaped hollow cathode ion source produces tiny carbon nanoclusters at greater concentration as compared to the cylindrical cathode. Similarly, the density of tiny nanoclusters enhances greatly with the increasing pressures (e.g., 75 mbar). In addition, the AFM morphology of the nanoclusters shows that they are more agglomerated at relatively lower pressure (e.g., 25 mbar). This may be due to the higher fragmentation of carbon soot with the increasing pressure because of more collisions among gas molecules and carbonaceous species. At controlled and optimized Ne-gas pressures and source geometry, carbon nanoclusters of the desired sizes can be fabricated, which may become promising candidates for nanoscale electronics, optoelectronic, and spintronic devices.