An investigation was made of Ni in Si samples with a wide range of initial doping concentrations by electron paramagnetic resonance, deep level transient spectroscopy and photo-electron paramagnetic resonance techniques. The results showed that the 2 different Ni-centers which were observed previously by electron paramagnetic resonance, but whose structure could not be interpreted unambiguously, were both associated with Ni in a substitutional position. They were distinguished by their charges and by slightly different displacements from the ideal substitutional site. A model for the Ni + s-center was suggested which explained the symmetry of this center.

Nickel in Silicon Studied by Electron Paramagnetic Resonance. B.Effey-Schwickert, M.Wiegand, H.Vollmer, R.Labusch: Applied Physics A, 77[5], 711-6