Structural and electronic properties of single-walled AlN nanotubes of different chiralities and sizes

Four models of single-walled AlN nanotubes (NTs), which possess (i) two different chiralities (armchair or zigzag type) and (ii) two different uniform diameters for both types of NTs (1 or 6nm) have been constructed, in order to analyse the dependence of their properties on both morphology and thickness. Periodic one-dimensional (1D) DFT calculations performed on these models have allowed us to analyse how the chirality and curvature of the NT change its properties as compared to both AlN bulk with either wurtzite or zinc-blende structures and their densely packed surfaces. We have found that the larger the diameter of the AlN NT, the smaller the width of its bandgap, the strengths of its bonds and the charge separations in them. This confirms the recent experimental finding of the possibility to adjust electronic properties in ultimate nanoscale optoelectronic devices produced from AlN and other group III nitrides.