  Recently, diluted Magnetic Semiconductors (DMS) doped with a small
concentration of magnetic impurities, especially DMS doped with transition
metal, inducing ferromagnetic DMSs have attracted a great interest. Using the
Monte Carlo method within the Ising model,we study the magnetic properties of
doped Mn ions in semi-conductor for different carrier's concentration. For the
case of Zn1-xMnxO, the results of our calculations show the effect of carriers
in understanding the existence and the control of the magnetic order. We give
also the exact values of carriers' concentration that should be adopted or
avoided in order to get ferromagnetic phase with high Curie temperature.
