Numerical simulation of intrinsic defects in SiO2 and Si3N4

The electronic structure of major intrinsic defects in SiO2 and Si3N4 was calculated by the MINDO/3 and the density-functional methods. The defects that are of interest from the standpoint of their ability to capture electrons or holes were considered; these centers include the three-and two-coordinated silicon atoms, the one-coordinated oxygen atom, and the two-coordinated nitrogen atom. The gain in energy as a result of capturing an electron or a hole with allowance made for electronic and atomic relaxation was determined for these defects. The experimental X-ray spectra for both materials are compared with calculated spectra.