Electronic structures of GaN nanotubes

Density functional calculations are used to predict the electronic structures of GaN nanotubes. The graphitic GaN is an indirect band gap material with valence band maximum at K edge. Zigzag nanotube is a semiconductor with direct band gap, whereas armchair nanotube has an indirect band gap along the tube axis. The band gaps decrease with the decreasing diameter, contrary to the case of carbon nanotubes.