Two single-layer porous gallium nitride nanosheets: A first-principles study

The gallium nitride (GaN) is a novel wide-gap semiconductor for photoelectric devices. In this paper, two 2D single-layer GaN crystal structures, called H-GaN and T-GaN, are discovered by the density functional theory calculations. The phase stability is confirmed by phonon dispersions. The sole-atom-thick crystals of H-GaN and T-GaN, has possess enlarged specific surface area than the graphene-like allotrope (g-GaN) due to the porous structures. In addition, they have indirect band gaps of 1.85-1.89 eV and the electronic structures can be further modulated by applied strains. For example, T-GaN transforms from an indirect semiconductor to a direct one due to compressed strains. Both the combination of high specific surface area and moderate band gaps make these 2D crystals potential high-efficiency photocatalysts. Our results will also stimulate the investigations on 2D GaN nano crystals with rich electronic structures for wide applications.