Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 55: Nanomaterials - Nanocrystalline & Porous Materials II

MM 55.5: Talk

Thursday, March 14, 2013, 12:45–13:00, H25

Diffusion-induced recrystallization in Si/Ge — •Michael Kasprzak, Sebastian Manuel Eich, Dietmar Baither und Guido Schmitz — Institut für Materialphysik, Westfälische Wilhelms-Universität, Münster

In size-mismatched thin film interdiffusion couples, Diffusion-Induced Recrystallization (DIR) appears rather than conventional Fickian interdiffusion. New grains formed in the diffusion zone reveal characteristic stepwise composition levels. Based on experiments with metallic thin films, we derived recently a quantitative model which combines thermo-elastic driving forces and grain boundary migration [1-3]. Observed concentration levels are such that the stress in front of the moving grain boundary reaches a maximum. This stress is rather high, close to the theoretical maximum strength of the material at the relevant temperature. In new experiments, we study this effect in semi-conductor layers, Ge on Si, for the first time. Heat treatment was performed in two stages: first annealing at 650°C to crystallize the pure Ge layer; second annealing at higher temperatures to initiate interdiffusion. Transmission electron microscopy and energy dispersive X-ray spectroscopy show that new grains of characteristic composition are indeed formed towards the Ge side of the diffusion couple similar as previously observed with fcc metals. Characteristic concentrations are derived from XRD data and compared with the suggested model.

[1] Schmitz et al. Scr Mater 63 (2010) 484; [2] Kasprzak et al. Acta Mater 59 (2011) 1734; [3] Eich et al. Acta Mater 60 (2012) 3469