By using valence-band and Si 2p core-level photo-electron spectroscopy, it was shown that short-range order in the amorphous oxynitride was governed by the Mott rule. That is, each Si atom was coordinated with four O and/or N atoms, each O atom (as in SiO2) was coordinated with two Si atoms, and each N atom (as in Si3N4) was coordinated with three Si atoms. The effect of removing Si-Si bonds (hole traps) from the interface of SiO2/Si by nitridation, and the cause of Si-Si bond creation near to the top surface of gate oxynitrides in semiconductor devices, could be understood for the first time by invoking the Mott rule.

V.A.Gritsenko, J.B.Xu, R.W.M.Kwok, Y.H.Ng, I.H.Wilson: Physical Review Letters, 1998, 81[5], 1054-7