The Fe-based III-V diluted magnetic semiconductor (III-V-DMS), (Ga, Fe)As, has been
grown successfully on GaAs(001) substrates by molecular beam epitaxy at a substrate
temperature T
s ranging from 260–350°C. Secondary ion mass spectroscopy analysis has
exhibited that the film composition can be expressed by Ga1-x
Fe
x
As. X-ray diffraction data
have indicated that the lattice constant of Ga1-x
Fe
x
As decreases with increasing Fe composition.
Magnetization data have exhibited that epilayers are predominantly paramagnetic, however,
their detailed behavior differs from that of Mn-based DMS systems. The work has
demonstrated that the physical properties of III-V-DMS can be changed significantly by the
choice of transition metals.
Preparation of GaAs–Fe composite structures has been studied by molecular-beam epitaxy. Enhanced magnetization has been observed under the red-light irradiation at 160 K. Through the study of both magnetization and magnetotransport characteristics, we believe that enhanced magnetization is strongly related to the interaction between photogenerated carriers and magnetic inclusions.
Extended x-ray absorption fine structure and near-edge x-ray absorption fine structure techniques are employed to investigate the local structure and valency about Fe atoms in the diluted magnetic alloy semiconductor system Ga 1Ϫx Fe x As prepared by molecular-beam epitaxy under various conditions. This experiment is aimed at elucidating possible correlations between the microstructures in these diluted magnetic semiconductors and some physical properties. Our x-ray results offer direct evidence of Fe substitution for Ga sites in GaAs prepared at relatively low substrate temperatures, wherein the Ga 1Ϫx Fe x As compound is mainly paramagnetic. However, the Fe impurity atoms could form small Fe clusters and/or Fe-As complexes when the samples are grown at high temperatures.
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