Strain relaxation through islands formation in epitaxial SiGe thin films

The mechanisms of strain relaxation and island formation have been investigated by transmission electron microscopy techniques in highly strained SiGe thin films. Furthermore the distribution of the strain field inside the substrate in proximity of the interface has been studied and qualitative information has been drawn. Results have shown that the substrate takes part to the relaxation process and that the strain field is mainly concentrated underneath islands with the higher values of the strain gradient located near the edges of each island.