Abstract
The remarkable structure, electrical, mechanical, and chemical properties of carbon nanotubes have generated great interests in many fields. It is especially interesting in the electrical property that carbon nanotubes may behave as metals or semiconductors depending on their diameters and helicity. It is therefore necessary to control the structure of carbon nanotubes precisely in order to make the applications in the devices. It is apparently not practical to acquire the electronic properties through the changing of the diameter and helicity of carbon nanotubes. The method of doping extraneous elements in carbon nanotubes has been undertaking to overcome the difficulty. Based upon the consideration, attempts were made to dope other elements into carbon nanotubes followed by the analysis and characterization.Microwave plasma enhanced chemical vapor deposition (MPECVD) has been used to synthesize the carbon nanotubes and the carbon nanotubes with various dopants. A catalyst film, e.g. (Fe, Co, Ni, Pd, Pt) was first sputtered on the substrate to promote the growth of carbon nanotubes, then in the chamber of MPECVD, where the mixture gas of methane and hydrogen was introduced and simultaneously decomposed by the microwave to synthesize carbon-related nanotubes. For characterization, SEM was used to observe the surface morphology; TEM was used to observe the microstructure and to characterize the crystal structure; ESCA was used to analyze the chemical composition and bonding type; Raman spectrum was used to judge the degree of graphitization; EPR was used to measure the dangling bonds and unpaired electrons.The growth of plasma sea urchins was found during the synthesis of carbon nanotubes. This unique morphology possesses a very high specific surface area and has been suggested as a potential storage material for hydrogen and lithium. Excessive dangling bonds were formed on the doped carbon nanotubes, on which adatoms are easily attached to the dangling bonds on the surface of CNTs to form quantum dots. A novel way to fabricate the metal quantum dots on the doped carbon nanotubes is being underway and the difficulty for choosing the substrate caused by the lattice constant mismatch can be avoided.