Observation of Threading Dislocation Generation Process in Highly Lattice-Mismatched Heteroepitaxy

The generation process of threading dislocations in highly lattice-mismatched heteroepitaxy was investigated by transmission electron microscopy (TEM). In the growth of InAs epilayers on GaAs substrate, the misfit strain was partially accommodated by the formation of coherent three-dimensional islands before the generation of misfit dislocations. However, the misfit dislocation was eventually introduced in each grown three-dimensional island in order to relieve the misfit strain. It was clearly shown that the misfit dislocations propagate towards the growth direction; i.e., threading dislocations originated from the grown islands.