First Principles Study on Electronic and Optical Properties of Single Walled Carbon Nanotube for Photonics Application

Abstract

Recent research works on single-walled carbon nanotube (SWCNT) based material has witnessed a great technological importance in photonic applications due to their unique optical characteristics. Present work aims to employ theoretical first principles study to explore the electronic and optical properties of SWCNT in the form of armchair nanotube. The theoretical simulation is done by using density functional theory (DFT) as implemented in the CASTEP computer code. Similar to almost gapless nature of graphene, formation of Fermi level of a relaxed SWCNT structure is found to be at a value approaching zero. The calculated electronic band structure shows a direct band gap of 0.259 eV with Dirac cone form between conduction and valence band. The optical spectrum shows a variation of real and imaginary of dielectric function with inter-band transition taking place along with frequency of the incident light. The absorption spectrum exhibits a significant degree of anisotropic characteristic with almost transparent nature ranging from near infrared to ultraviolet energy range. These optical spectra show excellent nonlinear optical features which remark the suitability in optoelectronic applications.