XAFS studies of the local structure of Mn doped dilute magnetic semiconductors

The great expectation is put in so called diluted magnetic semiconductors (DMS). The desired ferromagnetic semiconductor should have the Curie (Tc) temperature above the room temperature and have the capability to create material with nand ptype of conductivity in the same crystal. One of the example of such a material is extensively studied GaAs with Mn added as the magnetic material. The highest ferromagnetic phase transition temperature (Tc) reported so far in GaMnAs is close to 170 K, for GaMnAs containing about 8% of Mn. Tc is proportional to the Mn content and to the concentration of valence band holes. High Tc can be achieved in the material from which compensating defects are removed during the post-growth annealing procedures. The composition of GaMnAs is limited to about 10% Mn due to the Mn segregation into MnAs precipitates observed above this limit.