56Fe +-ion implantation effects in Al 2O 3

Abstract

Single and polycrystalline Al 2O 3 were implanted at room temperature with 60 keV 56Fe + ions with the dose range from 2.0 × 10 16 up to 1.2 × 10 17 ions/cm 2 using a 200 keV ion implanter. 56Fe +-ion implantation effects in Al 2O 3 have been studied directly after by using four complementary techniques: Vibrating Sample Magnetometer (VSM), Rutherford Backscattering Spectroscopy (RBS), Grazing-angle X-ray Diffraction (GXRD) and X-ray Photoelectron Spectroscopy (XPS). The specimens implanted with above 6.5 × 10 16 Fe +/cm 2 showed the behavior of paramagnetism or ferromagnetism which depend upon the ion dose or the size of α-Fe particles precipitated inside Al 2O 3 regardless of the crystallinity. The precipitation of α-Fe has been confirmed by the grazing-angle X-ray diffraction. From X-ray diffraction line broadening, it has been confirmed that the size of α-Fe particles in the single Al 2O 3 monotonically increases from 6.0 to 10.8 nm with the variation of the ion dose. The single Al 2O 3 implanted with Fe + ions has had larger effective magneton number and the coercivity than those of polycrystalline Al 2O 3. The difference in the effective magneton number and the coercivity with the crystallinity is due to the differences in Fe depth profiles in the implanted layers. From XPS depth profiles, the relative ratio of metallic Fe is increased according to the increase of Fe concentration regardless of the crystallinity but oxide states of Fe were nearly constant throughout the depth profiles.