Numerical simulation of intrinsic defects in SiO2 and Si3N4

The electronic structure of major intrinsic defects in SiO2 and Si3N4 was c alculated by the MINDO/3 and the density-functional methods. The defects th at are of interest from the standpoint of their ability to capture electron s or holes were considered; these centers include the three- and two-coordi nated silicon atoms, the one-coordinated oxygen atom, and the two-coordinat ed nitrogen atom. The gain in energy as a result of capturing an electron o r a hole with allowance made for electronic and atomic relaxation was deter mined for these defects. The experimental X-ray spectra for both materials are compared with calculated spectra. (C) 2001 MAIK "Nauka/Interperiodica".