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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