Role of strain in the stability of hetero-epitaxial island on nanopillars

Optoelectronics and microelectronics call for new techniques aiming at producing even smaller crystalline components of higher quality. Hetero-epitaxial growth on nanopatterned substrates such as nanopillar forests, is a promising direction to reduce mismatch strain and to obtain higher quality crystals. Indeed, 3D islands are grown on top of the pillars in a configuration which is similar to that of superhydrophobic liquid drops. However, as opposed to the case of liquids, elastic strain plays a major role in hetero-epitaxy. Using Kinetic Monte Carlo Simulations including elastic effects, we have studied in details the stability of a solid hetero-epitaxial island at the top of a nanopillar. We show that mismatch strain strain induces novel states for the island, including spontaneous symmetry-breaking and partial impalement of the islands in the nanopillars. Our results also suggest possible instabilities for solid-state catalytic particles governing nanowire growth.\\[4pt] [1] M. Ignacio, Y. Saito, P. Smereka, O. Pierre-Louis, preprint (2013).\\[0pt] [2] M. Ignacio, O. Pierre-Louis, Phys Rev. B 86 23410 (2012).\\[0pt] [3] K. Takano, Y. Saito, O. Pierre-Louis, Phys Rev B 82 075410 (2010).