Melt Grown Crystals

For the most part, single crystals are grown from a melt of the compound, provided that melting the compound does not cause it to decompose, i.e.-... 

Difference in the environmental phases. Since the interface roughness will be different for the same crystal species depending on whether the crystal was grown from the melt, solution, or vapor phases, different growth forms are expected for different environmental phases. This implies that the Tracht of the same crystal species will depend on the structure of the environmental phases, the degree of condensation, and the solute-solvent interaction. 

It turns out to be simple. Nature rarely works with crystals as ideal as the ones considered in Section 7.12.3. Crystals are grown, e.g., from a melt, and in the general rush of crystallization, the majority of crystals grow with built-in defects and imperfections in the way in which their atoms are arranged. It is one type of these imperfections that contains the secret of nonvanishing, self-perpetuating steps. The... 

As is obvious, if the stoichiometric GaAs shows a congruent melting, the composition of the melt, from which a solid crystal is grown, has to be coincident with that of the grown crystal, i.e. stoichiometric. This seems not to be the case (see Figs 3.50 and 3.51). 

Fig. 15 Lateral habit of solution- and melt-grown polyethylene single crystals. The drawing are based on electron micrographs of Organ and Keller [64]—grown from solution—and of Toda [107]—grown from the melt...

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