Formation of self-assembled quantum dots induced by the Stranski–Krastanow transition: a comparison of various semiconductor systems

To account for the occurrence (or not) of the Stranski–Krastanow (SK) transition (two-dimensional to 3D change of surface morphology) during the epitaxial growth of various lattice-mismatched semiconductor systems, we present a simple equilibrium model taking into account not only the lattice mismatch, but also the dislocation formation energy and the surface energy. It demonstrates the importance of these parameters especially for II–VI systems such as CdTe/ZnTe and CdSe/ZnSe. For II–VIs indeed, as misfit dislocations are easier to form than in III–Vs (such as InAs/GaAs) or IV systems (Ge/Si), the 3D elastic transition is short-circuited by the plastic transition. Nevertheless, by lowering the surface energy cost, telluride and selenide quantum dots can also be grown as predicted by our model and as shown experimentally by reflection high-energy electron diffraction (RHEED), atomic force microscopy and optical measurements. This model is also applied to the case of GaN/AlN, before discussing its limits.