# Inversion of the exciton built-in dipole moment in In(Ga)As quantum dots via nonlinear piezoelectric effect

## TL;DR

This paper demonstrates that anisotropic biaxial stress can invert the exciton dipole moment in In(Ga)As quantum dots through nonlinear piezoelectric effects, combining experimental, modeling, and theoretical approaches.

## Contribution

It provides the first experimental evidence of exciton dipole moment inversion via nonlinear piezoelectricity in quantum dots, supported by a comprehensive model and k.p calculations.

## Key findings

- Biaxial stress can invert the exciton dipole moment.
- Nonlinear piezoelectric effects are essential to explain the observations.
- The phenomenon is linked to significant changes in diode current-voltage characteristics.

## Abstract

We show that anisotropic biaxial stress can be used to tune the built-in dipole moment of excitons confined in In(Ga)As quantum dots up to complete erasure of its magnitude and inversion of its sign. We demonstrate that this phenomenon is due to piezoelectricity. We present a model to calculate the applied stress, taking advantage of the so-called piezotronic effect, which produces significant changes in the current-voltage characteristics of the strained diode-membranes containing the quantum dots. Finally, self-consistent k.p calculations reveal that the experimental findings can be only accounted for by the nonlinear piezoelectric effect, whose importance in quantum dot physics has been theoretically recognized although it has proven difficult to single out experimentally.