BIS Study of Silicon Nitride: Experiment and Theory

X-ray bremsstraMiing isochromat spectroscopic (BIS) study of unoccupied electron states in silicon nitride was performed in an extended energy range. The sample was a 3100 Å layer of silicon nitride deposited on a silicon plate. The isochromat photon energy was 5415 eV. The measurement was performed up to about 250 eV above the BIS threshold. A pronounced maximum of the density of electron state at about lOeV and a weak extended structure up to 200eV were observed. Calculations of the BIS intensity in extended energy range have been performed for silicon nitride using a muffin-tin potential approximation, multiple scattering method and partial probabilities of BIS transitions. The main result is that the BIS of silicon nitride is produced mostly at silicon ions and the BIS extended structure forms mainly due to electron scattering by nearest neighbouring nitrogen ions