Tuning electronic properties and band gap engineering of defective carbon nanotube bundles: first principles calculations

In this work, we theoretically studied band gap and Fermi energy response to uni-axial strain for defective carbon nanotubes bundles. We found that chirality plays a crucial role in band gap variations, while uni-axial strains show different responses and characteristics in the band gap. Besides, chiral '(n, n/2) for (n/3) ? integer' in nanotubes bundle shows different characteristics including band gap opening/closing with non-linear behavior. Furthermore, our results reveal that both defective carbon nanotubes bundles under study show close to systematic down shifts followed by up shifts in the Fermi energy in response to the applied uni-axial strains, respectively. Besides, our simulation results show a parabolic behavior in Fermi energy as well. This nonlinear behavior in Fermi energy may attributed to uneven electronic effects in both valence and conduction bands, whereas, these bands are directly responsible for the Fermi energy parabolic behavior. Our results are not only providing helpful understanding to the electronic properties of defective carbon nanotube bundles under uni-axial strain, but also opening an interesting opportunity for potential and future applications of bidirectional carbon nanotube bundles based electronic devices.