The geometrical and electronic properties of paramagnetic point defects were studied by using ab initio quantum-chemical methods. By using cluster models and gradient-corrected density functional theory or configuration interaction wave functions, a study was made of the N3=Si• and Si2=N• paramagnetic point defects. The computed ground-state properties and, in particular, the hyperfine coupling constants of N3=Si• and Si2=N•, the vibrational. spectra of the corresponding hydrogenated centers, N3=Si-H and Si2=N-H, and the valence density of states were correctly described. This confirmed the adequacy of the cluster models which were used for the study of point defects in this nitride.

Electronic Structure and Spectral Properties of Paramagnetic Point Defects in Si3N4. G.Pacchioni, D.Erbetta: Physical Review B, 1999, 60[18], 12617-25