Lattice constant, effective mass, and gap recovery in hydrogenated ${\mathrm{GaAs}}_{1-x}{\mathrm{N}}_x$

Upon weak N alloying, GaAs exhibits a giant photoluminescence redshift, a reduction of the lattice constant, and an increase of the electron effective mass. Post-growth hydrogenation was experimentally observed to restore the band gap, lattice constant, and effective mass to those of pure GaAs. We present ab initio density-functional calculations on pristine and hydrogenated GaAsN showing that the formation of $\mathrm{N}-{\mathrm{H}}_2^{*}$ complexes explains all three effects. We also discuss the gap bowing and some of the structural properties of GaAsN.