Growth process and characterization of magnetic semiconductors based on GeMn alloy films

The growth mechanism of thin Ge1–xMnx/Ge(100) diluted magnetic semiconductor films have been stud- ied by reflection high energy electron diffraction (RHEED) technique and correlated to the structural and magnetic properties of the films provided by X-ray diffraction (XRD) and magneto-optical Kerr effect (MOKE), respectively. The RHEED analysis evidenced a transition from a bi-dimensional to a three- dimensional growth mechanism at deposition temperature, TG, lower than 433 K while XRD characteriza- tion showed a polycrystalline structure with Ge grain size depending on TG. At low TG (343 K) all the Ge1–xMnx films behaved superparamagnetically, while at TG = 433 K hysteresis loops were observed, with a maximum Curie temperature of ≈ 250 K, for 0.027 < x < 0.044