Disorder-Induced Effects in III-V Semiconductors with Mn

The substitution of Mn in the III-V diluted magnetic semiconductors leads to a strong electron scattering on impurities. Besides the features induced in the valence band by the hybridization with the Mn d-states, also the conduction band is affected by the absence of the Mn s-states at its edge. Also the high concentration of compensating donors modifies the band structure. This is shown on the absorption coefficientε$\text{}_{2}$(ω) of GaP doped with Mn and Se. The absorption evaluated by ab initio density functional calculations starts with a smooth tail and does not show the structure typical of III-V materials. We analyze these features and the role of the donors on model systems using the tight-binding coherent potential approach.