The properties of paramagnetic point defects were studied by means of ab initio quantum-chemical methods, using cluster models and gradient-corrected density functional theory or configuration interaction wave functions. An investigation was made of the N3=Si• and Si2=N• paramagnetic point defects. The hyperfine coupling constants of N3=Si• and Si2=N•, the vibrational spectra of the corresponding hydrogenated centres, N3=Si–H and Si2=N-H and the valence density of states were all correctly described. This demonstrated the suitability of cluster models for studying 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