Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 55: Topical Session Growth Kinetics V

MM 55.1: Talk

Thursday, March 25, 2010, 14:00–14:15, H4

Atomic scale simulations of silicon growth from the melt: Formation of twins and stacking faults studied by molecular dynamics and Monte Carlo methods — •Johan Pohl and Karsten Albe — Institut für Materialwissenschaft, TU Darmstadt, Petersenstr. 32, D-64287 Darmstadt

Formation of twin boundaries and stacking faults at the silicon growth front is studied by lattice Monte Carlo and molecular dynamics (MD) simulations. First, we show how to construct a computationally efficient lattice-based Monte Carlo model that includes stacking faults and twin boundaries and allows to simulate crystal growth of large systems. Data on the importance of stacking faults for the roughening transition of the (111) interface and parallel twin growth velocities are extracted from the model.

In a further step, MD simulations reveal that twins do not nucleate on (111) microfacets in the perfect crystal, but exclusively occur in the vicinity of grain boundaries [1]. Only at an undercooling of 150 K we observe the formation of metastable twin bounded loops with incoherent interfaces to the matrix consisting of coherency and anticoherency dislocations. We conclude that the nucleation of stable twins in silicon growth requires the presence of a grain boundary or more general of a three-phase boundary, but is unlikely to occur on ideal (111) facets because of the excess energy of the interfacial area between matrix and twinned crystal.