Point-defect complexes in crystalline silicon composed of hydrogen, nitrogen, and oxygen atoms were studied within density-functional theory. Ab initio random structure searching was used to find low-energy defect structures. New, lowest-energy, structures were found for several defects: the triple-oxygen defect, {3Oi}, triple oxygen with a nitrogen atom, {Ni,3Oi}, triple nitrogen with an oxygen atom, {3Ni,Oi}, double hydrogen and an oxygen atom, {2Hi,Oi}, double hydrogen and oxygen atoms, {2Hi,2Oi} and four hydrogen/nitrogen/oxygen complexes, {Hi,Ni,Oi}, {2Hi,Ni,Oi}, {Hi,2Ni,Oi}, and {Hi,Ni,2Oi}. It was found that some defects form analogous structures when an oxygen atom was replaced by a NH group, for example, {Hi,Ni,2Oi} and {3Oi}, and {Hi,Ni} and {Oi}. The defect formation energies obtained were compared using various oxygen chemical potentials and the relative abundances of the defects were investigated.

Hydrogen/Nitrogen/Oxygen Defect Complexes in Silicon from Computational Searches. A.J.Morris, C.J.Pickard, R.J.Needs: Physical Review B, 2009, 80[14], 144112