Electronic structures and optical properties of GaN nanotubes with MgGa–ON co-doping

Both the electronic structures and the optical properties of single-walled zigzag GaN nanotubes (NTs) with MgGa–ON co-doping are investigated using first-principles calculations. We find that the MgGa–ON defect complex can exist stably in GaN NTs. The direct band gap width of the GaN NTs can be reduced by means of the MgGa–ON co-doping. The electrons of the valence band maximum (VBM) state are localized around the N atoms bonded with the Mg atom. The imaginary part ε2 of the complex dielectric function of GaN NTs with MgGa–ON co-doping has a sharp peak closely related to the optical transitions between the VBM and conduction band minimum states.