Abstract:
We use the density-functional calculations to investigate the compositional dependence of the lattice constant of (Ga,Mn)As with various native defects. The lattice constant of perfect mixed crystals does not depend on the concentration of Mn but it increases if some Mn atoms occupy interstitial positions. The same happens if As antisite defects are present. A quantitative agreement with the observed compositional dependence is obtained for materials close to a complete compensation due to these two donors. The increase of the lattice constant of (Ga,Mn)As is correlated with the degree of the compensation: the materials with low compensation should have lattice constants close to the lattice constant of GaAs crystal.