Atomic and electronic structures of stair-rod dislocations in Si and GaAs films were studied using first-principles calculations. It was shown that the stair-rod dislocation exhibited dimer-bond reconstruction in the core region and that there were two types of dimer-array configuration: parallel and zig-zag dimer structures. The bonding and anti-bonding states originating from these dimer bonds were embedded in valence and conduction bands in the case of Si, while they appeared as partially occupied mid-gap bands and acted as carrier traps in the case of GaAs. It was found that the adjacent dimer bonds in GaAs had differing lengths on different partial dislocation lines in order to stabilize the electronic band energy.

Atomic and Electronic Structures of Stair-Rod Dislocations in Si and GaAs. R.Kobayashi, T.Nakayama: Japanese Journal of Applied Physics, 2008, 47, 4417-21