Simulation of oxygen-containing complexes at silicon–silicon interface in cluster approximation

Abstract

Transformation of the “core” at the tilt Σ5 θ = 37° [001]/(130) grain boundary (GB) in silicon due to incorporation of oxygen atoms is studied using a method of molecular orbitals – linear combinations of atomic orbitals (MO LCAO) in PM3 approximation. A simple picture is proposed to interpret the calculated energy levels of cluster model. The results indicate that the oxygen aggregations in the grain boundary “core” may induce electrically active centers in the energy gap of silicon. In particular, a study of the electronic structure of the obtained SiOx complexes in the grain boundary “core” shows that the formation of oxygen-containing complexes with x = 2, 3 and 4, having three-fold coordinated O-atoms, results in the arising of bound states in the forbidden zone shifted to the band gap center with increasing x. Also it was shown that these states possess amphoteric properties, i.e. they can be both traps and donors for majority carriers.