Quantum confinement and excitonic effects in vertically coupled quantum dots

摘要

Recently, nearly perfect vertically coupled quantum dots have been constructed using self-organization method [1]. It has been demonstrated that either a blue shift or a red shift of the fundamental transition energy can be realized in different coupling conditions and it was proposed that this is due to the interplay of strain and electron - hole Coulomb interaction [2]. In this work, properties of excitons in vertically coupled GaAs/AlGaAs quantum dots were investigated using the variational method within the envelope function and effective mass approximations. It was found that the optical transition energy is reduced when the thickness of the spacer layer becomes less than about one exciton Bohr radius. This is a result of increased space extension of exciton due to the penetration of carrier wave functions into the spacer layer and corresponding reduction in confinement energy and Coulomb interaction between the electron and the hole.