Quantitative study of molecular N2 trapped in disordered GaN:O films

The structure of disordered GaN:O films grown by ion-assisted deposition is investigated using x-ray absorption near-edge spectroscopy and Raman spectroscopy. It is found that between 4 and 21% of the nitrogen in the films is in the form of molecular ${\mathrm{N}}_{2}$ that interacts only weakly with the surrounding matrix. The anion to cation ratio in the GaN:O host remains close to unity, and there is a close correlation between the ${\mathrm{N}}_{2}$ fraction, the level of oxygen impurities, and the absence of crystalline order in the GaN:O matrix.