Surface Concentration Mapping of InAs/GaAs Quantum Dots

By using X-Ray Photoemission Electron Microscopy we have obtained two-dimensional maps of the in-plane surface composition of InAs/GaAs self-assembled quantum dots. The chemical analysis reveals a higher In composition on the dot surface, with respect to the surrounding wetting layer, with a concentration increasing from the sides to the center of the dots. Comparison with concentrations found in the core of similar dots suggests strong In segregation on their surface, similarly to the surrounding wetting layer.