Group-IV-diluted magnetic semiconductor Fe_xSi_(1_x) thin films grown by molecular beam epitaxy

摘要

Fe_xSi_(1-x)-diluted magnetic semiconductor films with thickness 40 nm but different Fe concentrations of 4% and 7% were grown on Si(100) substrates at 200 or 250℃ by molecular beam epitaxy. Cross-sectional transmission electron microscopy observation confirms the epitaxial growth of the Fe_xSi_(1-x) films on Si substrate, and no Fe-related clusters are found in the films. Uniform distributions of Fe are observed along the growth direction in the films, showing no significant surface segregation of Fe atoms during the growth of the films. Measurements of the Hall effect at room temperature show that the carrier type is hole in the films. Anomalous Hall effect is observed at 26 K, suggesting that ferromagnetic ordering may exist in the films below 26 K.