Misfit accommodation at epitaxial interfaces

The papers presented in this special volume address the critical issues of the mechanisms by which epitaxial films accommodate the interfacial misfit through strain relaxation. In this concluding paper, we wish to highlight some of the important concepts associated with the misfit accommodation at epitaxial interfaces. Towards the goal of achieving defect free epitaxial layers, efforts are continuously made to understand the mechanisms of generation of misfit dislocations. Thermodynamic equilibrium considerations are important in this respect. However, nucleation and growth is considered to be the limiting step for the misfit dislocation generation in the semiconductor heterostructures. Strained superlattice structures have been used to reduce the propagation of threading dislocations. Similarly, patterned substrates are also employed to reduce the propagating dislocation density in the epilayers. These different ideas are used to produce defect free epitaxial structures for device construction. The present state of our understanding of dislocation nucleation and generation are critically examined in this paper and suggestions for future work are given in this paper.