The electronic properties of phosphorus-doped GaN nanowires from first-principle calculations

[Display omitted] •The P impurities tend to enrich at the surface of GaN nanowires.•The lattice parameters of GaN nanowires are changed by the P impurity.•Donor impurity level appears when the P impurity substitutes for the Ga atom.•The band gap decreases slightly when the P impurity substitutes for the N atom. The electronic properties of phosphorus-doped unsaturated and saturated gallium nitride (GaN) nanowires have been investigated from first-principles using the ultrasoft pseudopotential method. The results of these calculations indicate that the P impurities are enriched at the surface of gallium nitride nanowires, and that the structural symmetry of GaN nanowires is broken due to changes in the lattice parameters. When the P impurity substitutes for the Ga atom, the width of band gap increases at the Γ point, a donor impurity level appears in the band gap, and the P impurity and adjacent N atoms exists covalent interaction. Moreover, when the P impurity substitutes for the N atom, the width of the band gap decreases slightly at the Γ point, there is no obvious impurity level in the band gap, and P–Ga covalent bonds are formed, including those composed of ionic bonds. These conclusions indicate that the incorporation of P impurities can improve the field emission performance of GaN nanowires, which is consistent with the experimental results.