Energetics and electronic structures of AlN nanotubes/wires and their potential application as ammonia sensors.

Aluminium nitride (AlN) one-dimensional (1D) nanostructures, including crystalline nanowires, faceted nanotubes and conventional single-walled nanotubes, were investigated by means of density functional theory (DFT) using the generalized gradient approximation (GGA). While the larger diameter crystalline nanowires are the most favoured energetically of all these 1D nanostructures, the thick faceted nanotubes have comparable binding energies and can be obtained experimentally. The single-walled nanotubes have the lowest binding energies, and are less feasible experimentally. Due to the surface states at the band edges, the band gaps of all the AlN 1D nanostructures are much smaller than that of bulk AlN. The band structures of AlN nanowires can be modified by NH(3) adsorption. Consequently AlN nanowires have potential applications as gas sensors, since their electronic structures are very sensitive to NH(3) adsorption.