Short Range Order and the Nature of Defects and Traps in Amorphous Silicon Oxynitride Governed by the Mott Rule

Using valence band and Si $2p$ core level photoelectron spectroscopy, it is shown that the short range order in amorphous silicon oxynitride $\left(a-{\mathrm{SiO}}_x{\mathrm{N}}_y\right)$ is governed by the Mott rule. According to this rule, each Si atom is coordinated by four O and/or N atoms, each O atom (as in ${\mathrm{SiO}}_2$) is coordinated by two Si atoms, and each N atom (as in ${\mathrm{Si}}_3{\mathrm{N}}_4$) is coordinated by three Si atoms. The nature of the removal of Si-Si bonds (hole traps) at the interface of ${\mathrm{SiO}}_2/\mathrm{Si}$ by nitridation and the origin of Si-Si bond creation near the top surface of gate oxynitride in metal-oxide-semiconductor devices are understood for the first time by the Mott rule.