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Droplet epitaxy symmetric InAs/InP quantum dots for quantum emission in the third telecom window: morphology, optical
Paweł Holewa1,2, Shima Kadkhodazadeh3,4, Michał Gawełczyk5,6
1DTU Fotonik, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark.
Nanophotonics (Berlin, Germany)
|December 5, 2024
Summary
Researchers developed symmetric InAs/InP quantum dots (QDs) using droplet epitaxy for quantum communication. These emitters achieve high single-photon purity in the third telecom window, overcoming previous limitations in entanglement generation.
Area of Science:
- Quantum communication technology
- Semiconductor quantum emitters
- Nanophotonics
Background:
- Quantum communication demands deterministic single-photon and entangled photon pair sources compatible with telecom wavelengths.
- Indium arsenide/indium phosphide (InAs/InP) quantum dots (QDs) are promising candidates due to their emission efficiency.
- Existing InAs/InP QDs suffer from in-plane asymmetry, leading to significant fine-structure splitting (FSS), hindering entangled photon generation.
Purpose of the Study:
- To engineer symmetric InAs/InP quantum dots for efficient generation of single photons and entangled photon pairs.
- To address the challenge of fine-structure splitting in InAs/InP quantum dots for improved quantum emitter versatility.
- To achieve high-quality quantum emission in the third telecom window for integration with existing infrastructure.
Main Methods:
- Utilized droplet epitaxy (DE) to synthesize low surface density InAsP QDs on an InP substrate.
- Developed an analytical model to explain pit formation and QD base shape modification during DE.
- Performed theoretical calculations of electronic states and optical investigations (ensemble and single QD spectroscopy) to characterize QD properties.
Main Results:
- Achieved InAsP QDs with symmetric in-plane profiles, located in etched pits with concave bases.
- Demonstrated negligible FSS in ensemble measurements, indicated by vanishing linear polarization.
- Observed moderate FSS in single QD spectra after post-growth processing, attributed to environmental changes.
- Attained high single-photon emission purity of 92.5% in the third telecom window.
Conclusions:
- Droplet epitaxy enables the fabrication of symmetric InAs/InP QDs with desirable properties for quantum communication.
- The developed DE method overcomes the FSS limitation, paving the way for versatile entangled photon pair sources.
- These QDs represent a significant advancement towards practical quantum communication systems operating in the third telecom window.
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