The Growth Mechanism Of CCVD Nanotubes in Production (Nanotransistor - Nanochips)

Note:  In nanoscience and nanoelectronics, the structure of materials calculations, fracture toughness or fracture toughness is a property that describes the resistance that objects with cracks show against fracture  . This parameter is important for all solids design applications and is represented by KIc. Fracture toughness  is a calculation method for brittle failure when cracks are present in the material. If the fracture toughness of a material is low, that material will break brittle, and  the higher the fracture toughness, the higher the probability of soft fracture.

Temperature is the most important difference between gas and solid source based methods. In CCVD, low temperature is usually used and nanotubes  are grown at a temperature below 0111 degrees. More than one mechanism can be involved in the growth of carbon nanotubes depending on the type of gaseous precursor, the catalyst used and the operating parameters  . The mechanism of dissolution-infiltration-precipitation is one of the most common, which mostly prevails in low temperature methods. In this  mechanism, catalytic nanoparticles of metal alloys or transition metals (such as nickel, iron and cobalt) are considered spherical or floating on the surface of the substrate  . Hydrocarbon vapor (such as CO, CH4, C2H2, C2H4 and C2H6) (when It makes contact with the hot particles of the catalyst,  decomposes into carbon and hydrogen, and the carbon penetrates into the substrate metal.

When the carbon atom in the catalyst reaches a supersaturated value, the deposition and growth of  carbon nanotubes begin. If the interaction of the catalyst with the substrate is weak (the metal with the substrate has an acute contact angle), the nanotube grows at the bottom of the catalyst (tip growth),  and if the interaction of the catalyst with the substrate is strong, the metal with the substrate has an open contact angle. The nanotube grows at the top of the catalyst  . In the first case, it is possible to produce a nanotube with an open end.  The physical shape of the deposited carbon nanotube is single-walled, multi-walled, and the graphite layer covering the catalyst nanoparticles  depends on many factors, such as the size of the catalytic particles and the deposition rate. When the deposition rate is equal to or less than the carbon penetration rate, a graphite layer  is formed around the catalytic nanoparticles. When the deposition rate is greater than the carbon penetration rate, the carbon nanotubes are formed. The size of the catalytic nanoparticles  plays an important role in the growth of the nanotubes Generally, catalytic nanoparticles with small size (less than 01 nm) are active for the nucleation and  growth of carbon nanotubes.

If the particle size is about one nanometer, a single-walled nanotube is formed. Catalytic nanoparticles with a size of 01 to 51 nm lead to the growth of multi-walled nanotubes. Also, catalytic nanoparticles with a size larger than 51 nm are coated with amorphous graphite sheets  . And making chips and nano-transistors is an example of the effect of the crystal structure of the catalyst on the shape and structure of the carbon nanowire.

Different definitions of the change in the material structure have been presented for the production of chips and electronic elements of nanoscience.

The science of nanoelectronics is the study of phenomena and the manipulation of materials on atomic, molecular and macromolecular scales, which leads to a drastic change in the properties of materials (compared to large-scale materials).