Nanosensors with a combination of hydrogen and fluorine (PhD in nano-microelectronics) 

Researcher  and author: Dr.   (   Afshin Rashid)

Note: In the electrical structure of hybridization (metal nanotubes), the reaction with hydrogen gas and fluorine, by entering  SP3, converts the electrical structure of hybridization of metal nanotubes into semiconductors. 

These reactions sometimes damage the nanotube walls and lead to the formation of amorphous carbon or graphite layer structures. By hydrogenating single-walled nanotubes, the semiconductor nature of SWCNTs increases at room temperature. Strong plasma or high temperature reaction engraves the wall of metal nanotubes. That semiconductor SWCNTs are not damaged. Therefore, controlling the reaction conditions is very important. In nanotubes, reaction with methane plasma  removes metal SWCNTs without degrading  semiconductor SWCNTs. In the  method of using soft nanomolecular hydrogen plasma  in which hydrogen plasma is  used to convert metal SWCNTs to  semiconductor SWCNTs, in  which case the nanotube walls are  not destroyed or engraved. These reactions, which take place in the gas phase,  result in the fabrication of large-scale TFTS and  FETS with semiconductor nanotubes,  which is critical to the commercialization of high-efficiency nanotube-based equipment  . By selecting the appropriate reactant gases, this  method can also be used for selective reaction with  semiconductor nanotubes. By reacting SWCNTs SO3 as  under neutral gas in the presence of gas; Reagent gas inside the furnace at 400 ° C, semiconductor nanotubes preferably  react with gas  . The nanotubes are then heated to a temperature of 900 °  C to recover metal  defects with structural defects. This process is  a simple way to enrich the nanotube sample from Nanotubes are metal. Mass production of metal nanotubes  can be done by more precise control of reaction conditions  and ultimately increase the production scale  of its uses, including conductive films and  transparent electrodes.

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

1.   First, the nanotube metal to a semiconductor,   turn that off of the type of metal   used and end the nanotube metal is   the first reaction along with the establishment of the electron and the   loss of symmetry and a dash of energy   at the Fermi level nanotube metal Creates. 

2.  The second reaction conjugate all systems into a  series of smaller aromatic compounds through the  open CC bonds in the structure of nanotubes  makes. The end result of both modes  is the acquisition of semiconductor  nanotubes suitable for the manufacture of nanoelectronic equipment  .

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

Conclusion :

There  are  several   drawbacks to covalent methods   . First of all, most nanotubes become functional   and as a result the electronic structure of   SWCNTs is defective. Second,   due to the strong reaction,  it is difficult to  purify the product from   amorphous carbon. Most importantly, there is   no covalent reaction after   which the nanotube (m, n) can be  purified  uniformly   .

Researcher   and author: Dr.   (   Afshin Rashid)

PhD in Nano-Microelectronics