First-Principles Calculations of AlN Nanowires and Nanotubes:  Atomic Structures, Energetics, and Surface States

Abstract

We explore the atomic and electronic structures of single-crystalline aluminum nitride nanowires (AlNNWs) and thick-walled aluminum nitride nanotubes (AlNNTs) with the diameters ranging from 0.7 to 2.2 nm by using first-principles calculations and molecular dynamics simulations based on density functional theory (DFT). We find that the preferable lateral facets of AlNNWs and thick-walled AlNNTs are {1010} surfaces, giving rise to hexagonal cross sections. Quite different from the cylindrical network of hexagons revealed in single-walled AlNNTs, the wall of thick-walled AlNNTs displays a wurtzite structure. The strain energies per atom in AlNNWs are proportional to the inverse of the wire diameter, whereas those in thick-walled AlNNTs are independent of tube diameter but proportional to the inverse of the wall thickness. Thick-walled AlNNTs are energetically comparable to AlNNWs of similar diameter, and both of them are energetically more favorable than single-walled AlNNTs. Both AlNNWs and AlNNTs are wide band gap semiconductors accompanied with surface states located in the band gap of bulk wurtzite AlN.

Geometry and diameter dependence of the electronic and physical properties of GaN nanowires from first principles

“…Zheng et al 25 report that the band gap of hydrogen-saturated Si [001] nanowires decreases with increasing diameter, over the diameter range of 7-27 Å. Zhao et al 29 found that the strain energy of unsaturated AlN [0001] nanowires is inversely proportional to the nanowires diameter, for nanowires with diameters ranging from 7-22 Å. Schmidt et al To date there has been no comprehensive investigation into the atomic and electronic structures of GaN nanowires and their dependence on diameter and geometry, nor the effect of saturation of dangling bonds. The present work represents the first such extensive study of these systems, which we perform using first principles density functional theory calculations.…”

“…There have also been a number of recent electronic structure calculations of other semiconductor nanowires including Si, [24][25][26][27] ZnO, 28 AlN, 29 GaAs, 30 and InP.…”

Ab initio calculation of wurtzite‐type GaN nanowires

“…Surprisingly, there have been only few attempts to give a theoretical description of group III-nitride NWs from the first principles. Electronic structure calculations have been performed for both hydrogen-passivated and non-passivated group III-nitride NWs [5,6]. The widening of the bulk band gap is observed, although surface states within the band gap also have been seen [6].…”

“…Electronic structure calculations have been performed for both hydrogen-passivated and non-passivated group III-nitride NWs [5,6]. The widening of the bulk band gap is observed, although surface states within the band gap also have been seen [6]. There exists also a theoretical study on GaN single-crystal nanotubes (SCNT) devoted to the atomistic simulation of elastic properties [7].…”

Mg doping and native N vacancy effect on electronic and transport properties of AlN nanowires

“…Peng et al [39] have theoretically pointed out that the transition energy levels reduce monotonously with the increase in Mg doping concentration in AlN nanosheets. Several theoretical works have related to the 1D AlN nanostructures by considering the geometry and electronic structures of AlN nanotubes or nanoribbons [38,[40][41][42], the piezoelectric properties [43] and the surface effects of AlNNWs [44,45], the electronic structures of the coaxial nanocables of Al-NNW core and carbon/BN nanotube shell [46], the hydrogen storage property of AlNNWs [47,48], and the structural and electronic properties of GaN-AlN nanotubes and nanowires [49,50]. It is found that the AlN 1D nanostructures could indeed bring about novel physical properties, for example, band gaps of AlN nanotubes/wires are much smaller than that of bulk AlN [51].…”