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DS: Fachverband Dünne Schichten
DS 40: Thin Film Properties: Structure, Morphology and Composition I
DS 40.4: Vortrag
Donnerstag, 19. März 2020, 15:45–16:00, CHE 89
Impurity-Enhanced Solid-State Amorphization and Its Influence on Thin Film Formation — •Koen van Stiphout — Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven, Belgium — 2nd Institute of Physics, Georg-August-University Göttingen, 37077 Göttingen, Germany
The growth of amorphous compound thin films at the interface between a metal film and a semiconductor substrate upon annealing, has been studied extensively in the past. However, little is known about the influence of impurities of such a solid-state amorphization (SSA) reaction. Using in situ techniques, including synchrotron X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS), we show that when small amounts of nitrogen impurities (< 2 at.%) are implanted under the right conditions, the amorphous, intermixed layer during the Ni-Si reaction can reach thicknesses of almost 70 nm before crystallizing, an order-of-magnitude thicker than in the unimplanted system1. The delayed crystallization of the amorphous layer has profound effects on the reaction path of the system, as the early stages of phase formation become an interplay of long-range diffusion and kinetic nucleation barriers. Furthermore, we show that the increased stability of the amorphous phase is not just a particularity of the solid-phase reaction, but a general property of the Ni-Si system. At the heart of this impurity-enhanced SSA reaction lies the strong asymmetry in atomic mobility of the elements, which is increased due to the addition of an immobile, insoluble impurity element.
1 K. van Stiphout et al. 2019, J. Phys. D: Appl. Phys. 52, 145301