Thermal And Electronical Conductivity Of Carbon Nanotubes And Their Application

Carbon nanotubes are nano-sized tubes rounded up by single of multi-layered graphite. Carbon nanotubes can conduct heat with a velocity of up to 1000m/s. Carbon nanotubes'electronic conductivity depends on its diameter and spire angle, and can turn out to be either semi-conductive or metallic. Semi conductive carbon nanotubes can be used as the channel of CNTFET, while metallic carbon nanotubes can be used as wires in the micro- and nano- sized systems.Carbon nanotubes prepared by all means contains some impurities, and in the second chapter, we investigate the advantages and disadvantages of air oxidation and wet oxidation (by both 3mol/L HNO3 solution and H2SO4: HNO3 = 3:1 solution), and decided the best conditions for the purification of CNTs.Because of its structure characteristic, Carbon nanotubes are easily tangled together. In chapter two, we discussed the effect of Paa coating on purified CNTs.Fourier law and N-S equation may not be suitable for substances in the micro- and nano- world, thus we must investigate some other means to measure the thermal conductivity of the substances in this category. In chapter three, based on the data collected on air thermal conductivity, we proposed a much proper measurement:ν- the velocity of thermal conduction, and thus tested the radial thermal conductivity of CNTs. Metal/CNTs composite materials have a lot of extraordinary performances. In chapter four, we prepared metal/CNTs composites using electroless and electro-plating, and decided the best conditions for the preparation technique.Compared with Si MOSFET, CNTFET shows great improvements. In chapter five, The preparation process channel in carbon nanotube field effect transistor (CNTFET) was reviewed, including AFM manipulation, CVD in-situ growth of single-walled carbon nanotube (SWCNT), AC dielectrophoresis and L-B manipulation, etc. Based on the structures and preparation techniques , some existing problems were discussed, such as the burning down of metallic SWCNT, scale-down of Schottky barrier, elimination of hysteresis and the transfer of p-type CNTFET into n-type CNTFET. The specific solutions were proposed.