ABSTRACT
The term heteroepitaxy is really a misnomer for epitaxy itself, which implies the growth of layers of different crystal structure on substrates. It is used to emphasize the distinction from homoepitaxy, the growth of a crystal on itself, which is simply crystal growth and has little to do with epitaxy. The epitaxial relationship need not correspond to that in which the interface between the two crystals has minimum energy, although that may be the case. Although the details of interface structure in epitaxial systems will depend greatly on the nature of bonding at the boundary, there is an important common denominator associated with the presence of misfit: interface coherence. Since epitaxial layers are not in the equilibrium state, it is appropriate to consider the nature of nucleation. Epitaxy implies the growth of one crystalline substance on another in which the two have a fixed crystallographic relationship between each other.
