Regensburg 2004 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 3: Ionenimplantation III

DS 3.5: Vortrag

Montag, 8. März 2004, 15:30–15:45, HS 31

Swift heavy ion beam induced solid-state reaction at metal-oxide/silicon interfaces — •Ammar Elsanousi¹, Wolfgang Bolse¹, Beate Schattat¹, and Siegfried Klaumünzer² — ¹Institut für Strahlenphysik, Universität Stuttgart — ²Hahn-Meitner Institut, Berlin

We have studied the induced effects that occur at the interfaces of metal-oxide/silicon bi-layers due to the irradiation with swift heavy ions. Three different systems were investigated: NiO/Si, TiO₂/Si, and Fe₂O₃/Si. The irradiations were carried out at liquid nitrogen temperature with ions ranging from 140 MeV Kr¹⁰⁺ to 350 MeV Au²⁶⁺ at fluences up to 3·10¹⁵ ions/cm². The samples were characterized by means of Rutherford Backscattering Spectrometry (RBS), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The as-deposited NiO films exhibit a large shift and broadening of the XRD peaks, which indicates strong in-plane stresses. At low irradiation fluences NiO/Si and Fe₂O₃/Si showed the usual random walk mixing behavior △σ² = kφ, while in TiO₂/Si a non-linear scaling △σ² = kφ + mφ² was observed, which indicates that mixing is driven by a chemical solid-state reaction. At higher fluences plateau-formation was observed at the low-energy Ni-edge in the RBS-spectra of NiO/Si, which indicates the formation of the Olivinephase Ni₂SiO₄. However, the XRD-spectra did not show any evidence for the crystalline form of this compound. At very high fluences, dewetting occurs for NiO and Fe₂O₃ and the former coherent oxide films agglomerate in small islands with micrometer dimension on top of the Si substrate.