Stability and electronic structure of AlN nanotubes

We predict the stability and electronic structure of aluminum nitride nanotubes based on calculations using density functional theory. The lower strain energy required in order to wrap up an AlN graphitic sheet into a tube and good thermal stability indicate the possibility for the formation of AlN nanotubes. All the AlN nanotubes are semiconductors with band gaps ranging from 2.84 to 3.95 eV. The zigzag nanotube is a semiconductor with a direct band gap, whereas the armchair nanotube has an indirect band gap. Contrary to the cases of carbon nanotubes, the band gap of AlN nanotubes increases with the increasing diameter of the tubes and saturates at a value corresponding to the calculated band gap of an AlN hexagonal sheet.