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.