Stark effect on the exciton spectra of vertically coupled quantum dots: Horizontal field orientation and nonaligned dots

We study the effect of an electric field on an electron-hole pair in an asymmetric system of vertically coupled self-assembled quantum dots taking into account their nonperfect alignment. We show that the nonperfect alignment does not qualitatively influence the exciton Stark effect for the electric field applied in the growth direction, but can be detected by application of a perpendicular electric field. We demonstrate that the direction of the shift between the axes of nonaligned dots can be detected by rotation of a weak electric field within the plane of confinement. Already for a nearly perfect alignment the two-lowest energy bright exciton states possess antilocked extrema as a function of the orientation angle of the horizontal field which appear when the field is parallel to the direction of the shift between the dot centers.