Reversed truncated cone composition distribution of In0.8Ga0.2As quantum dots overgrown by an In0.1Ga0.9As layer in a GaAs matrix

We present cross-sectional scanning tunneling microscopy results of self-organized ${\mathrm{In}}_{\text{0.8}}{\mathrm{Ga}}_{\text{0.2}}\mathrm{As}$ quantum dots covered by an ${\mathrm{In}}_{\text{0.1}}{\mathrm{Ga}}_{\text{0.9}}\mathrm{As}$ film inside a GaAs matrix prepared by metalorganic chemical vapor deposition. From images of quantum dots with atomic resolution, we determine a spatial distribution of the In composition within the dots with a shape of a reversed truncated cone. The wetting layer and the overgrown ${\mathrm{In}}_{\text{0.1}}{\mathrm{Ga}}_{\text{0.9}}\mathrm{As}$ layer show vertical intermixing.