The Growth And Character Research Of One Dimension Carbon Nanomaterial

Carbon nanotubes may have huge potential for future technology because of their superior electrical, mechanical, and chemical properties. For the study of electrical properties, individual high-aspect-ratio carbon nanofibers were grown in plasma enhanced hot filament chemical vapor deposition. The carbon nanofibers are 60–100 nm in diameter and 6–30 μm in length, with a density less than 10⁶/cm². Field emission data from individual carbon nanofibers have been measured using a small-diameter moveable probe. The field-emission properties were then studied. The field emission characteristics of CNFs showed a turn-on field about 5 V/μm, the field-emission current of 5 V/μm was 20 μA/cm², less than the field emission characteristics of carbon nanotubes . The experimental results vary with the length of CNFs and the position of a CNF, that indicate the field-emission properties decided from the work function of materials, applied field and field amplification factor. Furthermore, the dispersion with defection is the key factor that decides the field-emission current. At the same time, the electric transport properties of a single MWCNT without any post processing were studied in situ at room temperature in a scanning electron microscope chamber (SEM) equipped with a moveable probe. It is found that the as-grown single MWCNT has the capacity of carrying a large current with extremely stable high current densities of 10⁷ A/cm², as well as a very low resistance (about 34.4?) and high conductance (much larger than the quantum conductance G₀). In addition, the measurement of a single MWNT at different points demonstrated almost the same current-voltage characteristics. The experimental observation implies a quasi-ballistic conducting behavior occurring in the as-grown MWCNTs of large diameter, which can be attributed to the mechanism of multiple channels conducting.