Determination of the shape of self-organized InAs/GaAs quantum dots by reflection high energy electron diffraction

We report a reflection high energy electron diffraction study of InAs self-organized quantum dots grown on GaAs (001). We observe facet reflections along the [31̄0] and [13̄0] azimuths, which indicate that the quantum dot shape is pyramidal with bounding facets corresponding to a family of four {136} planes. The determined structure, which possesses C2v symmetry, is quite different both from square-base pyramidal geometries which have been assumed in recent electronic structure calculations, and from previously proposed structures which have been based upon incomplete reflection high energy electron diffraction data.