Local Mn structures in III-V diluted magnetic semiconductor (In,Mn)As

We describe the local Mn structures obtained by the X-ray absorption fine structure (XAFS) measurements for MBE-grown (In,Mn)As epilayers with high Mn compositions (Mn>0.1). Both homogeneous and inhomogeneous epilayers were investigated. For the inhomogeneous layers grown at T_s = 280°C, the entire shell structures are similar to those of NiAs-type bulk MnAs. For the homogeneous layers grown at T_s = 210°C, the first shell around Mn was found to consist of disordered structure of six As atoms. This shell is then surrounded by twelve In atoms from the host InAs. These results suggest that a small six-fold Mn center (r ≲ 4Å) imbedded in the zincblende host matrix is the stabilized form of Mn in the homogeneous III-V diluted magnetic semiconductors.