Density functional theory was applied to the Σ3 (111) silicon grain boundary, and the impurity effect of Ni, Fe, Cu or Cr atoms doped near to the boundary at both interstitial and substitutional sites was calculated. The order of segregation energies for the impurities was that Fe was greater than Cu, Ni or Cr at substitutional sites, and Cr was greater than Cu, Fe or Ni at interstitial sites. The calculated values were positive; indicating that segregation was not favoured in the Σ3 (111) grain boundaries. When a metal impurity was placed at a substitutional site, a new state in the fundamental gap was observed in the density of states and the band-gap was reduced. The calculated magnetic moments for transition metal-doped grain boundaries showed that they were quenched for Ni, Fe or Cu point defects.

First-Principles Calculations on Σ3 Grain Boundary Transition Metal Impurities in Multicrystalline Silicon. A.Suvitha, N.S.Venkataramanan, R.Sahara, H.Mizuseki, Y.Kawazoe: Japanese Journal of Applied Physics, 2010, 49, 04DP02