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Abstract: Heavy-ion irradiation of ferromagnetic thin layers changes their micromagnetic and microstructural properties, due to the production of defects, relaxation or build-up of stress, or changes of grain size. When the ion range exceeds the layer thickness, ion mixing processes take place, leading to the formation of silicide phases. The present study deals with Co(30 or 55nm)/Si bilayers irradiated at room temperature with 100- or 200keV Xe ions to fluences of up to 15×1015/cm2. The Si(100) wafers were either crystalline or pre-amorphized by 1keV Ar+ implantation. Rutherford backscattering spectroscopy, in-plane magneto-optical Kerr effect, and X-ray diffraction served to analyse the samples before and after irradiation. The results will be compared with those obtained for other heavy-ions for Co/Si bilayers and in similar studies on Fe/Si bilayers. [Copyright &y& Elsevier]

Abstract: Charge-state equilibration of ions moving in matter occurs within femtoseconds and when penetrating nanometer depths. Ion-beam mixing in bilayers, tens of nm thick, should therefore not depend on the charge state of the projectiles. As the experimental situation for metal/silicon bilayers irradiated with noble-gas ions of different charge-states is ambiguous, we studied interface mixing of Fe/Si(100) bilayers, induced by 100keV 40Ar, 180keV 86Kr and 250keV 132Xe ions, either singly and multiply charged (Ar8+, Kr11+, Xe17+). No significant influence of the ionic charge-state was established for Kr and Xe ions; a slightly higher mixing rate was found for Ar8+ than for Ar1+ irradiation. [Copyright &y& Elsevier]

Abstract: The present study deals with CrN/Si bilayers irradiated at room temperature (RT) with 120keV Ar ions. The CrN layers were deposited by d.c. reactive sputtering on Si(100) wafers, at different nitrogen partial pressures (2×10−4, 3.5×10−4 and 5×10−4 mbar), to a total thickness of 240–280nm. The substrates were held at room temperature (RT) or 150°C during deposition. After deposition the CrN/Si bilayers were irradiated up to fluences of 1×1015 and 1×1016 ions/cm2. Structural characterization was performed with Rutherford backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (XTEM) and grazing angle X-ray diffraction (XRD). For the highest nitrogen pressure (5×10−4 mbar) a pure stoichiometric CrN phase was achieved. The results showed that Ar ion irradiation resulted in the variation of the lattice constants, micro-strain and mean grain size of the CrN layers. The observed microstructural changes are due to the formation of the high density damage region in the CrN thin film structure. [ABSTRACT FROM AUTHOR]

Titanium nitride (TiN) thin films thickness of ∼260 nm prepared by dc reactive sputtering were irradiated with 200 keV silver (Ag) ions to the fluences ranging from 5 × 10 15 ions/cm 2 to 20 × 10 15 ions/cm 2 . After implantation TiN layers were annealed 2 h at 700 °C in a vacuum. Ion irradiation-induced microstructural changes were examined by using Rutherford backscattering spectrometry, X-ray diffraction and transmission electron microscopy, while the surface topography was observed using atomic force microscopy. Spectroscopic ellipsometry was employed to get insights on the optical and electronic properties of TiN films with respect to their microstructure. The results showed that the irradiations lead to deformation of the lattice, increasing disorder and formation of new Ag phase. The optical results demonstrate the contribution of surface plasmon resonace (SPR) of Ag particles. SPR position shifted in the range of 354.3–476.9 nm when Ag ion fluence varied from 5 × 10 15 ions/cm 2 to 20 × 10 15 ions/cm 2 . Shift in peak wavelength shows dependence on Ag particles concentration, suggesting that interaction between Ag particles dominate the surface plasmon resonance effect. Presence of Ag as second metal in the layer leads to overall decrease of optical resistivity of TiN. [ABSTRACT FROM AUTHOR]

Reactively sputtered CrN layer, deposited on Si(1 0 0) wafer, was implanted at room temperature with 80-keV V + ions to the fluence of 2 × 10 17 ions/cm 2 . After implantation the sample was annealed in a vacuum, for 2 h at 700 °C. The microstructure and chemical composition of CrN films was investigated using Rutherford backscattering spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and cross-sectional transmission electron microscopy (conventional and high-resolution), together with fast Fourier transformation analyses. It was found that vanadium atoms are distributed in the sub-surface region of CrN layer, with the maximum concentration at ∼20 nm. After annealing the formation of VN nanoparticles was observed. The nanoparticles are spherical shaped with a size of 8–20 nm in diameter. [ABSTRACT FROM AUTHOR]

Abstract: Studies on ion-irradiated transition-metal/silicon bilayers demonstrate that interface mixing and silicide phase formation depend sensitively on the ion and film parameters, including the structure of the metal/Si interface. Thin Co layers e-gun evaporated to a thickness of 50nm on Si(100) wafers were bombarded at room temperature with 400-keV Xe+ ions at fluences of up to 3×1016 cm−2. We used either crystalline or pre-amorphized Si wafers the latter ones prepared by 1.0-keV Ar-ion implantation. The as-deposited or Xe-ion-irradiated samples were then isochronally annealed at temperatures up to 700°C. Changes of the bilayer structures induced by ion irradiation and/or annealing were investigated with RBS, XRD and HRTEM. The mixing rate for the Co/c-Si couples, Δσ 2/Φ =3.0(4)nm4, is higher than the value expected for ballistic mixing and about half the value typical for spike mixing. Mixing of pre-amorphized Si is much weaker relative to crystalline Si wafers, contrary to previous results obtained for Fe/Si bilayers. Annealing of irradiated samples produces very similar interdiffusion and phase formation patterns above 400°C as in the non-irradiated Co/Si bilayers: the phase evolution follows the sequence Co2Si→CoSi→CoSi2. [Copyright &y& Elsevier]

Abstract: This paper presents a study of the structure and composition of reactively sputtered Cr-N layers as a function of deposition parameters, and the effects of ion implantation on these structures. The layers were deposited on (100) Si substrates to a thickness of 240–280nm, at different nitrogen partial pressure, and subsequently irradiated with 120keV Ar ions. Structural characterisation of the samples was performed with Rutherford backscattering spectroscopy, transmission electron microscopy and X-ray diffraction analysis. We also measured their electrical resistivity with a four point probe. It was found that the layers grow in form of columnar structures, and their composition, Cr2N or CrN, strongly depends on the nitrogen partial pressure during deposition. Ion irradiation induces local micro-structural changes, formation of nano-particles and defects, which can be nicely correlated to the measured electrical resistivity. [Copyright &y& Elsevier]

Thin Fe and Ta layers of 30–45 nm thickness, deposited via magnetron sputtering on Si (1 0 0) substrates, were bombarded at room temperature with 100 keV Ar1+ or Ar8+ or with 250 keV Xe1+ or Xe19+ ions in order to test the influence of the ion charge state on the surface sputtering and interface mixing. The samples were characterized by means of Rutherford backscattering at 0.9–3.0 MeV α-particle energy, time-of-flight elastic recoil detection analysis with a 53 MeV 127I10+ beam and atomic force microscopy. No influence of the charge state on the sputtering and athermal mixing rate was observed in the case of the Ta/Si system. However, in the case of the Fe/Si system, the ion charge was observed to have an influence on the mixing rate. [Copyright &y& Elsevier]

Abstract: This paper reports on a study of microstructrual changes in TiN/Si bilayers due to 200keV Ar+ ions irradiation at room temperature. The 240nm TiN/Si bilayers were prepared by d.c. reactive sputtering on crystalline Si (100) substrates. The TiN films were deposited at the substrate temperature of 150°C. After deposition the TiN/Si bilayers were irradiated to the fluences of 5×1015 and 2×1016 ions/cm2. The structural changes induced by ion irradiation in the TiN/Si bilayers were analyzed by Rutherford Backscattering Spectroscopy (RBS), X-ray diffraction analyses (XRD) and Transmission Electron Microscopy (TEM). The irradiations caused the microstructrual changes in TiN layers, but no amorphization even at the highest argon fluence of 2×1016 ions/cm2. It is also observed that the mean crystallite size decreases with the increasing ion fluence. [Copyright &y& Elsevier]