Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 13: Symposium Modern Metallic Materials Design III
MM 13.8: Vortrag
Dienstag, 28. März 2006, 12:30–12:45, IFW B
Metal-like growth of silicon during rapid solidification — •Riping Liu1, Q. Wang1, Q. Jing1, M. Z. Ma1, Christian Panofen2, and Dieter M. Herlach2 — 1Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, Hebei, P. R. China — 2Institute of Space Simulation, German Aerospace Center DLR, D-51170 Koeln, Germany
In the theory of crystal growth, two idealized mechanisms, lateral growth and continuous growth, have been proposed. Systems with atomically rough or diffuse interfaces are thought to grow by the continuous growth mechanism. In this case, the solid-liquid interface is assumed to be rough on atomic scale so that the atoms can attach themselves uniformly on the interface. The grown crystals present non-faceted surface morphologies, as for metals. On the other hand, the solid-liquid interface may be atomically smooth except for the presence of atomic steps. Crystal growth in this case is lateral or edgewise. Atoms transferring from liquid to solid are first attached to the steps. The finally grown crystals often present faceted morphologies, as for silicon, germanium, and most of compounds.
Silicon is normally considered to grow in a faceted way. From our experiments on solidification of undercooled melt, however, growth of silicon at the beginning is continuous, just like that of metals. But with increasing of the crystal size or decreasing of the undercooling level, it will be transited to the faceted way.