Stark effect on the exciton spectra of vertically coupled quantum dots: horizontal field orientation and non-aligned dots

TL;DR

This paper investigates how electric fields affect exciton spectra in vertically coupled quantum dots, revealing that non-perfect alignment influences the Stark effect primarily under perpendicular fields and can be detected through field rotation.

Contribution

It introduces a method to detect non-perfect alignment of quantum dots by analyzing exciton energy shifts under rotated horizontal electric fields.

Findings

Non-perfect alignment does not qualitatively change the Stark effect for vertical fields.

Perpendicular electric fields can reveal non-alignment.

Rotation of horizontal fields detects the direction of dot misalignment.

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.