Structural distortions in nitrogen-doped GaP and GaAs

Using the tight-binding approximation we investigated the effect of structural relaxation on nitrogen-induced states in GaP and GaAs. We show that deformation energies of the impurity depend on mutual orientation of nitrogen atoms and possibilities for them to relax. The calculated deformation energies that allowed us to remove the strain by changing atomic positions can determine the final position of cluster states. We show that the lowest nitrogen bound state is associated with the [1 1 0] nitrogen pair, while the upper bound state corresponds to the [2 0 0] pair. The contribution of Γ, L and X conduction band minimums into nitrogen-induced states is evaluated.