Near-edge X-ray absorption fine-structure measurements at the N-K edge were used to monitor the evolution of defect-related structures, in the spectra of buried nitride films, as a function of the implantation dose. The buried films were prepared by implanting 35keV 14N+ ions into Si, to doses ranging from 2 x 1017 to 2 x 1018/cm2. Defect-related resonances, RL1 and RL2, appeared at 401.1 and 403.3eV, respectively. The RL1 resonance was characteristic of a defect structure at low and intermediate implanted doses, and could be annealed out with an activation energy of 0.5eV. The RL2 resonance was the signature of excess N in N-rich films. It was attributed to the transitions of 1s-electrons to unfilled states with p-component at a defect site which contained a N dangling bond. It could be annealed out only by prolonged annealing at 1150C.

E.C.Paloura: Applied Physics Letters, 1997, 71[22], 3209-11