# Low-Density InGaAs/AlGaAs Quantum Dots in Droplet-Etched Nanoholes

## TL;DR

This paper introduces a new method for creating quantum dots with improved properties for quantum photonics applications.

## Contribution

The paper presents InGaAs/AlGaAs quantum dots with extended emission wavelengths while maintaining low strain and controllable density.

## Key findings

- QD densities of ∼0.25 μm–2 were achieved.
- FSS values as low as 3 μeV were observed.
- Emission wavelengths extended to ∼900 nm at cryogenic temperatures.

## Abstract

Over the past two decades, epitaxial semiconductor quantum
dots
(QDs) have demonstrated very promising properties as sources of single
and entangled photons on-demand. Among different growth methods,
droplet etching epitaxy has allowed the growth of almost strain-free
QDs, with low and controllable surface densities, small excitonic
fine structure splitting (FSS), and fast radiative decays. Here, we
extend the technique to In­(Ga)As QDs in AlGaAs, thereby increasing
the achievable emission wavelength range beyond that accessible to
GaAs/AlGaAs QDs while preserving some of the key advantages of this
growth method. We observe QD densities of ∼0.25 μm–2, FSS values as small as 3 μeV, and short
radiative lifetimes of ∼300 ps, while extending the
achievable emission wavelength to ∼900 nm at cryogenic temperatures.
We envision these QDs to be particularly suitable for integrated quantum
photonics applications.