Stuructural characterization and growth mechanism of carbon nanotubes synthesized by chemical vapor deposition

Abstract

Structural characterization and growth mechanism of carbon nanotubes synthesized by chemical vapor deposition are studied. The structure and growth mechanism of carbon nanotubes using transmission electron microscopy, the effect of catalysts on carbon nanotubes, controlled growth of carbon nanotubes using catalytic nanoparticles, the effect of growth temperature on carbon nanotubes grown on the iron-deposited substrate, large-scale production of carbon nanotubes by vapor phase growth method using iron pentacarbonyl or tungsten hexacarbonyl, and the selective growth and field emission of carbon nanotubes on hole-patterns are presented. Specimens for transmission electron microscopy on the structure of carbon nanotubes are prepared by a novel cross-sectional method. The reciprocal lattice and electron diffraction patterns are inferred from the atomic structure of carbon nanotubes. The information about interface structure of carbon nanotubes/catalyst/substrate is investigated by cross-sectional transmission electron microscopy. At the initial stage growth of carbon nanotubes in chemical vapor deposition, driving force for the separation of graphite caps from catalytic metal results from stress energy due to the mismatch piled up at the edge side of the graphite cap. The carbon nanotubes grown by thermal chemical vapor deposition using iron thin film catalyst have bamboo-like structure. The tips of carbon nanotubes are closed and usually not encapsulated with catalytic particles. The base growth model for the bamboo-like CNT growth is proposed in thermal chemical vapor deposition process. The catalyst effect on the synthesis of carbon nanotubes using thermal chemical vapor deposition is investigated. The respective growth rate of carbon nanotubes shows that the performance of catalysts is in the order of nickel>cobalt>iron. The average diameter of carbon nanotubes follows the sequence of iron, cobalt, and nickel catalysts. The structure of carbon nanotubes reve...