Growth of an F Face of an Imperfect Crystal

Abstract

It is hard to imagine that a crystal of macroscopic dimension, obtained in real growth conditions, could be perfect. Imperfections of different kinds, from point defects and stacking faults to edge and screw dislocations, are almost unavoidably present in a crystal lattice. They can be introduced by external factors, such as impurities or foreign particles present in the mother phase and engulfed in the crystal during growth, by thermal stress due to temperature differences or quenching, and may even be a consequence of the growth mechanism itself, as is the inclusion and condensation of lattice vacancies, the incoherent encounter of growth fronts, etc. [211, 220]. In rare cases, nearly perfect crystals are obtained by pulling material from the melt in precise crystallographic directions that favor the climb of the dislocations and their elimination at the ingot surface [221].