Vacancy Defect Reconstruction and its Effect on Electron Transport in Si-C Nanotubes

Authors S. Choudhary , S. Qureshi
IIT Kanpur, Department of Electrical Engg., Kanpur, India
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Issue Volume 3, Year 2011, Number 1, Part 5
Dates Received 04 February 2011, published online 08 December 2011
Citation S. Choudhary, S. Qureshi, J. Nano- Electron. Phys. 3 No1, 1035 (2011)
PACS Number(s) 81.07.De, 73.22. – f, 71.15.Mb, 71.20.Nr
Keywords Nanotube (25) , SiCNT (2) , Armchair-zigzag (2) , Defects (12) , Vacancy (6) .
We investigate the vacancy defect reconstruction and its effect on I-V characteristics in a (4, 0) zigzag and (5, 5) armchair silicon-carbide nanotubes (SiCNTs) by applying self consistent non-equilibrium Green’s function formalism in combination with the density-functional theory to a two probe molecular junction constructed from SiCNTs. The results show that single vacancies and di-vacancies in SiCNTs have different reconstructions. A single vacancy when optimized, reconstructs into a 5-1DB configuration in both zigzag and armchair SiCNTs, and a di-vacancy reconstructs into a 5-8-5 configuration in zigzag and into a 5-2DB configuration in armchair SiCNTs. Introduction of vacancy increases the band gap of (4, 0) metallic SiCNT and decreases the bandgap of (5, 5) semiconducting SiCNT, bias voltage dependent current characteristic show reduction in overall current in metallic SiCNT and an increase in overall current in semiconducting SiCNT.

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