Equilibrium shape changes of nanocrystals induced by strain
Résumé
In this paper we establish a generalized Wulf-Kaishew theorem giving the equilibrium shape of a 3D crystal A deposited Ž. coherently onto a lattice mismatched planar substrate B. Our mains results are: 1 The epitaxial strain acts against wetting Ž. so that globally it leads to a thickening of the equilibrium shape. 2 Owing to the coherent strain the equilibrium shape changes with size. More precisely the various facet extensions change during the growth, some facets decreasing, some Ž. others increasing. 3 Each dislocation entrance, necessary for relaxing too large crystals having thus stored a prohibitive elastic energy, modifies abruptly the equilibrium shape and thus the different facet extension. Some experimental evidences are discussed. q