Near-edge X-ray absorption fine-structure studies of GaN under low-energy nitrogen ion bombardment

The electronic structure of p-type GaN layers exposed to low-energy nitrogen ion bombardment was studied by near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy. It was found that ion bombardment lead to the creation of states lying below the nitrogen absorption edge which posses p-symmetry. These states are attributed to nitrogen interstitials with different local topologies created during ion bombardment. Furthermore, the NEXAFS spectra also shows the development of a strong π*-resonance above the absorption edge with increasing incident nitrogen ion energy. This peak is attributed to the formation of molecular nitrogen at interstitial positions, arising from a build up of nitrogen ions on these sites.