ABSTRACT
Defect engineering in heteroepitaxial layers refers to efforts to control the densities, types, or arrangements of defects, especially dislocations. This chapter presents the theory and practice of the most common defect engineering approaches. In a number of heteroepitaxial material systems, it has been reported that the insertion of a strained layer superlattice (SLS) can reduce the threading dislocation density of the heteroepitaxial material, compared to the case of direct growth without an SLS. Nanoheteroepitaxy is a substrate-patterning approach that involves the growth of nanometer-scale islands on a mismatched heteroepitaxial substrate. A number of defect engineering approaches for heteroepitaxial layers have emerged. These include buffer layer approaches, patterned growth, patterning and annealing, epitaxial lateral overgrowth, nanoheteroepitaxy, and compliant substrates, to name a few. The proliferation of defect engineering methods could be taken as an indication that none of them are uniquely suited to the purpose for all material systems.
