Epitaxial growth and magnetic properties of ferromagnetic semiconductor Ge1-xFex thin films epitaxially grown on Si(001) substrates

Ferromagnetic semiconductor Ge1-xFex thin fins were grown on Si(001) substrates by low-temperature molecular ream epituxy. The crystal structure of the Ge1-xFex films was of diamond type for 0 <= x <= 17.5%. and their lattice constant monotonically decreased with increasing Fe content x. No precipitations of any other Fe-Ge phase were detected in structural characterizations. Magnetic circular dichroism (MCD) characterizations revealed that the origin of the ferromagnetic ordering, in the Ge1-xFex films comes from the diamond-type semiconductor phase. The anomalous Hall effect was clearly observed and their ferromagnetic behavior was consistent with the results of the MCD observations. As the Fe content increased. the resistivity of the film monotonically decreased. and simultaneously, the Curie temperature monotonically increased. All the experimental results indicate that the Ge1-xFex films grown on Si(001) have the properties of intrinsic ferromagnetic semiconductor.