Strain-induced interfacial hole localization in self-assembled quantum dots: Compressive InAs∕GaAs versus tensile InAs∕InSb

Using an atomistic pseudopotential approach, we study how the shape of the dot (spherical vs lens shaped) affects the position-dependent strain and the electronic properties of tensile (InAs∕InSb) and compressive (InAs∕GaAs) quantum dots. We compare the strain profiles, strained modified band offsets, confined levels, and atomistic wave functions of these dots. We show (i) how the existence of position-dependent strain in nonflat heterostructures can control the electronic properties, leading, for example, to interfacial localization of hole states on the interface of matrix-embedded dots and (ii) how the dots shape can control the level sequence and degeneracy. For example in spherical dots, one finds degenerate light-hole (LH) and heavy-hole (HH) states, whereas in lens-shaped dots one can have as the highest-occupied hole state either (a) a LH state inside the dot, becoming a HH state outside the dot (InAs∕InSb tensile case) or (b) a HH state inside the dot, becoming a LH states outside the dot (InAs∕GaAs compressive case).