With the increasing speed of microprocessors, copper interconnection technology on CMOS is becoming a bottleneck. A possible alternative is to use carbon nanotubes with higher electron mobility and smaller size. In 1991, when Ishima of NEC, Japan, inspected the spherical carbon molecules produced in the graphite arc equipment under the high-resolution transmission electron microscope, it accidentally found the carbon molecules composed of tubular coaxial nanotubes, which is called "Carbon Nanotubes", also known as Bucky tubes.

Carbon nanotubes have a typical layered hollow structure. there is a certain angle between the layers of carbon nanotubes. The tube body is composed of hexagonal carbon ring micro structural units, and the end cap part is a polygonal structure composed of pentagonal carbon rings, or a multilateral tapered multi wall structure. It is a kind of one-dimensional quantum material with special structure (the radial size is nanometer scale, the axial size is micrometer scale, and both ends of the tube are basically sealed).

At present, the common preparation methods of carbon nanotubes mainly include: arc discharge, laser ablation, chemical vapor deposition (hydrocarbon gas pyrolysis), solid phase pyrolysis, glow discharge, gas combustion, and polymerization synthesis. Arc discharge is the main method to produce carbon nanotubes. The preparation of carbon nanotubes using this method is relatively simple in technology, but the carbon nanotubes generated are mixed with C60 and other products, and it is difficult to obtain carbon nanotubes with high purity, and the obtained carbon nanotubes are often multilayer carbon nanotubes, while in actual research, people often need single layer carbon nanotubes. In addition, this method consumes too much energy. In recent years, chemical vapor deposition (CVD), or hydrocarbon gas pyrolysis, has been developed to overcome the shortcomings of arc discharge to some extent. In this method, gaseous hydrocarbons can be decomposed into carbon nanotubes at 800~1200 ℃ by passing the template attached with catalyst particles. The outstanding advantage of this method is that the residual reactant is gas, which can leave the reaction system to obtain carbon nanotubes with high purity. At the same time, the temperature does not need to be very high, which saves energy relatively. However, the diameter and shape of carbon nanotubes are irregular, and catalysts must be used in the preparation process.

According to the different size and shape, the electronic properties of carbon nanotubes can be divided into metal and semiconductor. In the process of using carbon nanotubes as transistors, scientists have encountered the problem that the artificially manufactured carbon nanotubes are a mixture of metal and semiconductor. These two kinds of carbon nanotubes stick to each other to form ropes or bundles, which greatly reduces the use of carbon nanotubes, because only semiconductor nanotubes can be used as transistors. Moreover, when carbon nanotubes with two properties stick together, their metallicity is stronger than that of semiconductors.

Nanoelectronic devices made of carbon nanotubes have the advantages of small size, high speed, low power consumption and low cost. They will replace silicon materials as important electronic materials in the post molar era. However, the construction of nano electronic devices using carbon nanotubes faces many technical problems. The connection between carbon nanotubes and metal electrodes is one of the bottlenecks in the manufacturing process of carbon nanotube devices.

Carbon nanotubes also have great application potential in the photovoltaic field. Nanometer solar cells may use hot carriers, multi band excitation, thermal photovoltaic and other principles to generate higher photoelectric conversion efficiency. For example, the carbon nanotube schottky barrier solar cell uses a plurality of single wall carbon nanotubes with uniform orientation to weld on the metal electrode, and generates current by using the schottky barrier formed between the carbon nanotube and the metal electrode and a back grid. This new solar cell structure does not need semiconductor doping, so there is no unnecessary defect and photogenerated carrier recombination loss caused by semiconductor doping. The diameter of single walled carbon nanotubes is about 1 nm, which has obvious quantum confinement effect, so it is possible to use solar photon energy more effectively. However, due to the small number of semiconducting carbon nanotubes used, it is possible to prepare large-area carbon nanotube Schottky barrier solar cell samples after solving the purification methods of a large number of semiconducting single-walled carbon nanotubes.