Electronic structure of amorphous Si3N4: experiment and numerical simulation

The electronic structure of amorphous silicon nitride was studied by XPS, X-ray emission, and ELS. The partial densities of states for silicon (3s, 3p, 3d) and nitrogen (2s, 2p) atoms were determined. The results of experiments were compared with the calculated electronic structure of Si3N4. The calculations were made using quantum-chemical semiempirical method MINDO/3 in cluster approximation. The top of the Si3N4 valence band in terms of band structure is two-degenerated. There are Si3s,3p-N2s,2p bonding states and N2pπ nonbonding states at the top of valence band. The electronic structures of Si3N4 and SiO2 are similar. The experimentally energy of plasmon oscillations determined for Si3N4 is 23.5 eV. It was found that not only Si3s,3p, N2p orbitals of upper valence band take part into plasmon oscillations but N2s states of lower valence band, too.