InAs quantum dots in multilayer GaAs-based heterostructures

Multilayer GaAs-based heterostructures grown by molecular beam epitaxy are studied by X-ray diffraction, and the mechanisms of formation of InAs quantum dots are discussed. Quantum dots, nearly pyramidal in shape, can be randomly or orderly distributed in the GaAs matrix. Ordering is already present in heterostructures containing as few as three layers of quantum dots. Superlattices of two types, coexisting in the same heterostructure, are formed. One of them is constituted of quantum dots and the other of equally spaced InAs wetting layers.