Reduction of band-gap energy in GaNAs and AlGaNAs synthesized by N+ implantation

We have studied the optical properties of nitrogen implanted GaAs and AlGaAs samples. The fundamental band-gap energy has been found to decrease with the increasing ${\mathrm{N}}^{\mathrm{+}}$ implantation dose in a manner similar to that commonly observed in GaNAs and GaInNAs alloys grown by molecular beam epitaxy or metal organic chemical vapor deposition. Our results indicate that ${\mathrm{GaN}}_x{\mathrm{As}}_{\text{1−x}}$ and ${\mathrm{Al}}_x{\mathrm{Ga}}_{\text{1−x}}{\mathrm{N}}_y{\mathrm{As}}_{\text{1−y}}$ alloys can be formed by implantation of nitrogen followed by appropriate postimplantation annealing treatments. As inferred from the magnitude of the band gap shift, the percentage of the implanted N atoms incorporated on the substitutional As sites is estimated to be around 12%.