Investigation of Facetted Growth in Heavily Doped Silicon Crystals Grown in Mirror Furnaces

Abstract

Herein, facets and related phenomena are studied for silicon crystals grown in the and directions, using the Zone Melting and Floating Zone techniques. Investigating the central facets of dislocation-free crystals as a baseline allowed for the determination of the local temperature gradients. When comparing these results to dislocated crystals, the presence of dislocations caused a clear reduction in the facet size, correlated with a reduction in the required local supercooling to estimated maximum values of around 0.6 K. Furthermore, for crystals grown on the rough {100} interface, attempts to provoke a morphological instability of the local phase boundary succeeded for crystallization velocities in the range of 10–16 mm/min, in good agreement with theory. Contrary to this observation, crystals grown in the direction remained morphologically stable even at higher crystallization velocities due to the stabilizing effect of the atomically smooth interface. Additionally, crystals grown in the direction with an oxygen skin by the Zone Melting technique reproducibly showed a non-periodic fluctuation of the central facet diameter at a certain translation velocity.

Keywords

• silicon
• floating zone
• zone melting
• facet
• dislocations
• growth kinetics