ABSTRACT
The growth of coherent thin layers on rigid crystalline substrates is possible when biaxial compressive or
tensile strain in the layer accommodates the lattice mismatch between the film and substrate material.
When the stored strain energy exceeds a certain threshold, the heterostructure becomes metastable and
the film strain may give way to misfit dislocations. The basic energetic and kinetic parameters describing
mismatch accommodation by elastic strain and misfit dislocation in metastable heterostructures appear
to be well described by the framework of Matthews and Blakeslee [1-3] and Dodson and Tsao [4, 5].
However, it is evident that they cannot adequately explain the point of strain relief onset via plastic flow
and the work hardening behavior of strained layers at the end of thermal relaxation process. This stems
from ignoring the effects of elastic surface relaxation on the film lattice cells and the elastic interaction
between straight misfit dislocations within the film-substrate interface. The first includes the problem of
developing a relationship between the equilibrium critical thickness at which dislocations form and the
bulk lattice mismatch [6]. The latter involves balancing the force required to move misfit dislocations
against the internal elastic stress field due to dislocation-dislocation interactions [7]. Finally, suffice it to
say that classical equilibrium and kinetic models for strained layer case do not imply rigorously the
conditions of equilibrium at the boundary.
