Invesitgaiton To The Electronic Properties Of Single Walled Carbon Nanotubes(SWCNTs)

Both Carbon nano tubes(CNTs) and Graphene are the latest nano materials, anddue to the exceptional physical and chemical properties, they have many potentialapplications in nano electronics and future quantum instrument making. This paperfirstly introduces current research on CNTs and it’s synthesis, application prospect,physical properties briefly, and then make investigation to electronic properties CNTs.Based on the geometric structure Graphene, using tight binding modelinvestigated the first Brillouion zone of Graphene depending the energy dispersionequation of Graphene applying periodic boundary condition obtained energydispersion relation of carbon Nano tubes with different chiral index. According to theenergy dispersion equation using Matlab software drow the possible energy dispersiondiagram, and analyzed the energy band structure of different CNTs. Results show that,single walled carbon nano tube with (n,n) index are shows metallic property with verysmall band gap. For armchair single walled carbon Nano tubes, when chiral index n/3equal to integer number, nano tube presents metallic electronic property, if it is not, itwill shows semi conductive electronic property; for chiral single walled carbon nanotubes if the chiral index differences (n-m)/3is integer, nano tube express metallicproperty. We also investigate first Brillouion zone of Graphene, results shows thatnano tubes electronic property strongly related to position of quantized wave vector K.Near the fermi energy point K, investigated the electronic density of state ofASWCNTs and ZSWCNTs, revealed the relation between band structure and diameterof single walled carbon nano tube in detail. Results shows that all the armchair carbonnano tubes are metallic with small band gap(approximately0.01088eV) independentof tube diameter. In this paper tube diameter is changes between0.3131nm to1.7628nm, while diameter is change from2.568eV to0.0108eV. This shows that inZSWCNTs band gap is the function of tube diameter. It is important to note that this paper use wide range of tube diameter, results shows that band gap inversely functionof tube diameter, and sensitivity of band gap decrees with increase of tube diameter,we also fund that TB model more accurately describe the band gap variation and DOSof carbon Nano tubes. For pure metallic nano tubes DOS takes zero value near thefermi energy points EF=0, while for semi conductive nano tubes it will take non zerovalue at this point. Moreover this paper also investigate the Van Hove singluarty inthe1D DOS of Zigzag metallic carbon nano tubes.This paper also discuss the effects of strain and trigonal wrapping effects on theelectronic properties of the nano tubes. Investigation shows that, small amount ofwrapping and strain has no significant effect on the energy band structure of CNTs,but larger strain will change orbital hybridization, thus having different effect on theelectronic properties of different tube.