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

Abstract

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 non-perfect alignment. We show that the non-perfect 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 non-aligned 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 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.

Coupled Quantum Dots - Spatial Correlations between Interacting Carriers

“…In a more realistic quantum disk model of confinement [14] the lateral localization radius for typical size and depth of the quantum well is about 1.2-1.5 times smaller than the one for the electron. The overestimated localization of the hole in the discussed model [7] does not introduce any qualitative consequences for the electric field effect applied in the vertical direction -as confirmed by our recent studies [10,12,11] where we used the three-dimensional quantum wells for modeling the confinement potential (Sects. 6 and 7).…”

“…In our modeling [6][7][8][9][10][11][12] we used the following Hamiltonian for the electronhole pair:…”

“…Results of this paper are discussed in this section. We considered nonidentical dots in later papers [7,[10][11][12] (see Sects. 5, 6, and 7).…”

“…[3] for instance). We recently studied [10] the consequences of the horizontal shifts between the axes of the dots on the exciton photoluminescence spectra. We used three-dimensional quantum well model of the dots with diameter of 20 nm and height of 4 nm after the experimental work [4].…”

“…Such measurements for a single pair of dots separated of the entire ensemble have been realized only relatively recently [4,5]. In the present paper we review our work on interacting electrons and holes in vertically stacked InGaAs/GaAs self-assembled quantum dots [6][7][8][9][10][11][12] in context of the photoluminescence experiments performed in external electric field.…”