Electronic structure of Si-Si bond in Si₃N₄ and SiO₂ : Experiment and simulation by MINDO/3

The trapping properties of the Si-Si bond in Si₃N₄ and SiO₂ were investigated. The MINDO/3 calculations show that the spin polarization of the Si-Si bond with a captured hole takes place in both SiO₂ and Si₃N₄. The ESR (Electron Spin Resonance) measurements were made in Si₃N₄ with captured electrons and holes. The number of localized carriers was of two orders of magnitude larger than that used by others. The ESR signal of localized electrons and holes was not observed. A new mechanism of the antiferromagnetic ordering of localized electrons and holes in an insulator with a large concentration of traps is proposed. According to this mechanism, the antiferromagnetic ordering in Si₃N₄ may be caused by the resonance tunneling of localized spins through nonoccupied traps. We believe that the deep traps responsible for the electron and hole capturing in Si₃N₄ are the Si-Si bonds.