Research On Preparation And Mechanismof Bamboo-Structured Carbon Nanotube

The work of this paper is to prepare carbon nanotubes by chemical vapor deposition system and studies effects of conditions of prepared carbon nanotubes on theirs diameter and growth speed. The first part mainly discusses effects of experimental conditions (such as reaction gases ,negative bias)on growth and structure of CNTs . CNTs were synthesized on Si substrates deposited with Ta buffer and NiFe films in plasma-enhanced chemical vapor deposition system(PCVD) and hot filament chemical vapor deposition system(HCVD). Their growth and structure were investigated by scanning electron microscopy(SEM) an transmission electron microscopy(TEM).The results indicate that the growth speed of CNTs is increased and their average diameter is almost unchanged . Through the SEM and TEM images of prepared CNTs under the reaction gases with N2 or without N2 , it can be concluded that N2 is a favorable factor to prepare aligned CNTs and form bamboo-structured CNTs . It is also found that negative bias is another important factor which can affect growth speed and diameter of CNTs. Because of the occurrence of glow discharge , a cathode sheath forms near the substrate surface , and a number of ions are produced in it , and a very strong electrical field builds up near the substrate surface. Under the effect of the field , the strong bombardment of ions on the substrate surface will influence the growth of aligned carbon nanotubes. And the negative bias decides the intensity of the bombardment of ions. The experimental results indicate that the average diameter of the aligned carbon nanotubes is reduced and the average length of the aligned carbon nanotubes is increased with increasing negative bias. And in plasma-enhanced chemical vapor deposition system, different CNTs were synthesized on Si substrates deposited with Ta buffer and Ti buffer, results indicate that the diameter of CNTs on the Si substrate with Ta buffer is smaller than CNTs'on the...