Xenon-ion-induced and thermal mixing of Co/Si bilayers and their interplay |
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Authors: | M Novakovi? K ZhangM Popovi? N Bibi? H HofsässKP Lieb |
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Affiliation: | a VINCA Institute of Nuclear Sciences, 11001 Belgrade, Serbia b II. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany |
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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 50 nm on Si(1 0 0) 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, Δσ2/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. |
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Keywords: | Ion beam mixing Thermal mixing Silicides TEM RBS XRD |
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