ABSTRACT
Up to now, we focused on heterostructures where all single-layer materials have the same crystal structure and identical lattice constant. Then, perfect interfaces can be expected. However, when putting different materials epitaxially one on top of the other, this condition is not always perfectly fulfilled. In this chapter, we will discuss some consequences from lattice mismatch between layers in a heterostructure. In some cases, this leads to the development of strain, as discussed below. Originally, people tried to avoid such strain by controlling the compositions of the heterostructures accurately. Later, it turned out that strain may lead even to dramatic advantages in some applications.
