Electronic Properties of GaN Nanotube: Ab Initio Study

The electronic properties of single wall (graphitic) zigzag GaN nanotubes (GaNNTs) (n, 0) (n = 3-15) with tube diameter (d(t)) ranging from 3.225 angstrom to 16.126 angstrom have been analyzed using ab-initio approach. The Density Functional Theory (DFT), with LDA-PZ and GGA-PBE as exchange-correlation functional, is employed to optimize the configuration and to evaluate the band structure of GaNNT with specified tube diameter (d(t)) and chirality (theta). The computation finds that at d(t) = 3.23 angstrom, LDA and GGA shows almost same bandgap, whereas at d(t) = 13.97 angstrom LDA shows metallic behavior and with GGA semiconducting. Noticeable, buckling has also been seen at d(t) = 11.825 angstrom, which increases as radius of nanotube increases. In another finding, GaNNT of single atomic layer shows smaller band gap in comparison to that of multi atomic layer and this variation has been explained in terms of presence or absences of inter layer interactions. Interestingly, the GaNNT of single atomic layer does not show monotonic, semiconducting or metallic behavior within diameter ranging from 3.225 angstrom to 16.126 angstrom.