Self-organized Electrical Nanostructure DND (Metal Nanotube) Combination and Reaction With Hydrogen and Fluorine Gas

Note: In the hybrid electrical structure (metal nanotube), the reaction with hydrogen and fluorine gas, by introducing  SP3, converts the hybrid electrical structure of the metal nanotube into a semiconductor.

These reactions sometimes cause the destruction of the nanotube walls, leading to the formation of amorphous carbon or graphitic layered structures. By hydrogenating single-walled nanotubes, the semiconducting nature of SWCNTs is enhanced at room temperature. Strong plasma or high-temperature reactions cause etching of the metal nanotube walls.  The semiconducting SWCNTs are not damaged.  Therefore, controlling the reaction conditions is very important.  In nanotubes, the reaction with methane plasma  removes the metal SWCNTs without destroying  the semiconducting SWCNTs. In  the method using a mild hydrogen nanomolecular plasma  , in which  hydrogen plasma is used to convert metal SWCNTs into  semiconducting SWCNTs, in  which case the nanotube walls  are not destroyed and etched.  These reactions, which are carried out in the gas phase,  allow the in situ and large-scale fabrication of TFTS and  FETS with semiconductor nanotubes,  which is very important for the commercialization of high-efficiency devices  based on nanotubes.  By choosing the appropriate reactant gases, this  method can also be used for selective reaction with  semiconductor nanotubes.  By reacting SWCNTs with SO3 as  an inert gas in the presence of the reactant gas inside the furnace at 400°C, the semiconductor nanotubes  preferentially  react with the gas . The nanotubes are then heated to 900°C  to recover the structurally defective  metal nanotubes  . This process is a simple way to enrich the nanotube sample from  metal nanotubes. Mass production of  metal nanotubes can be achieved by more precise control of the reaction conditions  , ultimately leading to increased  production scale for its applications, including conductive films and  transparent electrodes.

In general, based on the reaction rate,  selective covalent electrochemistry of metal nanotubes can  be divided into two categories:

1_  First, the metal nanotubes  are converted into a type of semiconductor, which causes the metal type to be quenched,  and the second is the elimination of the metal nanotubes.  The first reaction is accompanied by electron delocalization and loss  of symmetry, and creates an energy gap  in the Fermi level of the metal nanotubes.

2_  The second reaction converts all conjugated systems into a  series of smaller aromatic compounds by  opening the C-C bonds in the nanotube structure  . The end result of both cases  is the obtaining of semiconducting nanotubes, which  are suitable for the fabrication of nanoelectronic devices  .

In selective covalent reactions, the  reactant concentration is always important. And when the reactant concentration  is high, both types of nanotubes  are affected by the reaction. For example, in the case of FETS, increasing  the reactant concentration reduces the Off current  , resulting in an off/On ratio of more than  105. On the other hand, the strong reaction  reduces the mobility, which  is another important parameter for electronic devices. Therefore, there must  be a balance between the rate of reaction progress and the  final efficiency of the device.

Conclusion:

There are several  drawbacks to covalent methods  . First, the nanotubes  are often functionalized, resulting in  defects in the electronic structure of SWCNTs. Second,  the product is difficult to purify from amorphous carbon due to the violent reaction  . Most importantly,  there is no covalent reaction after which  the (m,n) nanotube can be  purified singly.