# Fine structure of excitons in InAs quantum dots on GaAs(110) planar layers and nanowire facets

## TL;DR

This study explores the optical properties of InAs quantum dots on GaAs(110) surfaces and nanowire facets, revealing insights into exciton behavior, polarization, and strain effects at low temperatures.

## Contribution

It provides new understanding of exciton fine structure and polarization control in InAs quantum dots on GaAs(110), including effects of strain and piezoelectric fields.

## Key findings

- Quantum dots emit between 1.1 and 1.4 eV at 10 K.
- Electron-hole coherence lengths are approximately 5 nm and 2 nm.
- Quantum dot photoluminescence is linearly polarized.

## Abstract

We investigate the optical properties of InAs quantum dots grown by molecular beam epitaxy on GaAs(110) using Bi as a surfactant. The quantum dots are synthesized on planar GaAs(110) substrates as well as on the {110} sidewall facets of GaAs nanowires. At 10 K, neutral excitons confined in these quantum dots give rise to photoluminescence lines between 1.1 and 1.4 eV. Magneto-photoluminescence spectroscopy reveals that for small quantum dots emitting between 1.3 and 1.4 eV, the electron-hole coherence length in and perpendicular to the (110) plane is on the order of 5 and 2 nm, respectively. The quantum dot photoluminescence is linearly polarized, and both binding and antibinding biexcitons are observed, two findings that we associate with the strain in the (110) plane This strain leads to piezoelectric fields and to a strong mixing between heavy and light hole states, and offers the possibility to tune the degree of linear polarization of the exciton photoluminescence as well as the sign of the binding energy of biexcitons.