Defects in hexagonal-AlN sheets by first-principles calculations

Abstract

Abstract. Theoretical calculations focused on the stability of an infinite hexagonal AlN (h-AlN) sheet and its structural and electronic properties were carried out within the framework of DFT at the GGA-PBE level of theory. For the simulations, an h-AlN sheet model system consisting in 96 atoms per super-cell has been adopted. For h-AlN, we predict a lattice parameter of 1.82 Å and an indirect gap of 2.81 eV as well as a cohesive energy which is by 6% lower than that of the bulk (wurtzite) AlN which can be seen as a qualitative indication for synthesizability of individual h-AlN sheets. Besides the study of a perfect h-AlN sheet also the most typical defects, namely, vacancies, anti-site defects and impurities were also explored. The formation energies for these defects were calculated together with the total density of states and the corresponding projected states were also evaluated. The charge density in the region of the defects was also addressed. Energetically, the anti-site defects are the most costly, while the impurity defects are the most favorable, especially so for the defects arising from Si impurities. Defects such as nitrogen vacancies and Si impurities lead to a breaking of the planar shape of the h-AlN sheet and in some cases to formation of new bonds. The defects significantly change the band structure in the vicinity of the Fermi level in comparison to the band structure of the perfect h-AlN which can be used for deliberately tailoring the electronic properties of individual h-AlN sheets.2

Van der Waals stacks of few-layer h-AlN with graphene: anab initiostudy of structural, interaction and electronic properties

“…1d). The good agreement of the properties of single-layer h-AlN obtained here with previous studies dedicated to this system [9,10], emphasizes the appropriateness of the level of theory chosen in this work for modeling stacks of h-AlN with graphene. Two-layer h-AlN can adopt five different stacking configurations following commonly introduced stacking configurations and notations [9]: two stacking configurations result as the hexagons of one layer reside on the hexagons of the other layer, e.g., Al over Al and N over N (AA), and Al over N and N over Al (AA'); other three stacking configurations result as the hexagons of one layer are translated with respect to the hexagons of the other layer, e.g., AB, AB', and A'B, Fig.…”

“…Our theoretical study on the structural and electronic properties of single layers of h-AlN further involved the incorporation of selected point defects (e.g., vacancies, as well as substitutional atoms of silicon and carbon) providing the prospect for deliberate tailoring of its electronic properties [10].…”

The adsorption of CO molecule on pristine, As, B, BAs doped (4, 4) armchair AlNNTs: a computational study

“…2. The average (Al-N) bond length is 1.811 Å parallel with the tube axis, and another is 1.818 Å diagonal to the tube axis which is in agreement with other researches [27,[32][33][34][35]. With doping of B atom, the bond lengths (Al-N) decrease significantly to 1.48 Å and with doping of As the bond lengths increase significantly to 2.369 Å .…”

h-AlN-Mg(OH)2van der Waals bilayer heterostructure: Tuning the excitonic characteristics

“…Almeida et al 30 investigated properties of defects, such as vacancies, antisites, and impurities, in h-AlN. It was reported that N vacancies and Si impurities lead to the breaking of the planar symmetry and cause significant changes in the electronic properties.…”