Effect of Facet Occurrence on Polytype Destabilization during Bulk Crystal Growth of SiC by Seeded Sublimation
Résumé
We report on polytype destabilization during bulk crystal growth of Silicon Carbide by seeded sublimation method. Polytype transitions are experimentally obtained and a thermodynamic analysis using classical 2D nucleation theory is used towards the understanding of the experimental results. Whether it is a thin lamella or an inclusion, it is found that the polytype transitions systematically occur on the (0001) facet. This suggests that the polytype switch takes place through classical 2D nucleation at the facet. We will show that two criteria must be fulfilled for the occurrence of a foreign polytype: i) minimization of nucleation energy and ii) presence of a facet. This is directly depending on the crystal shape (convex or concave) and its evolution with growth time.