Effect of annealing on carrier density and Curie temperature in   epitaxial (Ga,Mn)As thin films
  We report a clear correspondence between changes in the Curie temperature and carrier density upon annealing in epitaxially grown (Ga,Mn)As layers with thicknesses in the range between 5 nm and 20 nm. The changes are dependent on the layer thickness, indicating that the (Ga,Mn)As - GaAs interface has importance for the physical properties of the (Ga,Mn)As layer. The magnetoresistance shows additional features when compared to thick (Ga,Mn)As layers, that are at present of unknown origin. 
B. Sorensen, J. Sadowski, R. Mathieu, P. Svedlindh, and P. E. Lindelof