Exciton level crossing in coupled InAs/GaAs quantum dot pairs

The electronic and optical properties of vertical pairs of capped, structur ally identical InAs pyramidal quantum dots with {101} facets in GaAs are in vestigated theoretically. For distances smaller than 17 ML a strong distanc e dependent quantum coupling between the two dots is predicted for electron s, leading to a term splitting between the ground and the first excited sta te. Holes are asymmetrically affected by the strain and the piezoelectric p otential which, together, prevent a term splitting like in the electron cas e. The excited hole states vary in their character, dependent on the spacer thickness. Consequently, exciton absorption spectra significantly depend o n the vertical dot distance, regarding the energetic range, order, and shap e of peaks, and the polarization anisotropies.