The transformation of the “core” for the tilt Σ5 θ = 37° [001]/(130) grain boundary in polycrystalline Si due to incorporation of C atoms was studied with a method of molecular orbital–linear combinations of atomic orbital in the PM3 approximation. Insertion of C atoms into 5- or 7-fold interstitial positions at GB “core” formed donor-like complexes which were composed of combined Si2C, Si3C or Si4C configurations depending on number x of incorporated C-atoms. Energy levels of such complexes were shifted to the bottom of the conductive band from EC-0.536eV to EC-0.043eV with increasing x from 1 to 4.

Simulation of Carbon-Containing Complexes at Silicon–Silicon Grain Boundaries in Cluster Approximation. A.L.Pushkarchuk, A.M.Saad, A.K.Fedotov, S.A.Kuten: Thin Solid Films, 2005, 487[1-2], 142-6