Tuning structural and electronic properties of single wall AlN nanotubes

The electronic and structural characteristics of the armchair and zigzag single-walled AlN nanotubes (SWAlNNTs) have been considered by using density functional theory (DFT). The effects of tube diameter on the Al-N bond length, the buckling separation, tube lengths, valence band maximum (VBM), conduction band minimum (CBM), Fermi energy, strain energy, and bandgap have been studied. The strain energy calculation revealed that higher-diameter nanotubes are more stable than those with smaller diameters consequently at the same chirality armchair AlNNTs are more stable than zigzag types. It revealed a correlation between the bandgap and buckling: the smaller the bandgap, the higher the buckling, and the buckling separation increases by decreasing tube diameter. The 2p-orbitals of Al and N atoms have the most contribution to CBM and VBM, respectively. All zigzag and armchair AlNNTs are semiconductors having direct and indirect bandgap, respectively. It is also found that for both zigzag and armchair AlNNTs, with increasing nanotube diameter, the bandgap increased. The conclusions of this study can definitely be useful in future experimental works on optoelectronic devices.