Strain-free, symmetrical, InGaAs quantum dots as single photon emitters in the telecomC-band

TL;DR

This paper reports the design and fabrication of strain-free, symmetrical InGaAs quantum dots on GaAs(111)A substrates that serve as high-quality single-photon emitters in the telecom C-band, suitable for quantum communication.

Contribution

The authors introduce a novel strain-free growth method for symmetrical InGaAs quantum dots on GaAs(111)A, enabling efficient single-photon emission in the telecom C-band.

Findings

Quantum dots exhibit emission in the 1400–1600 nm range.

Exciton lifetimes are approximately 1.3–1.9 ns.

Single-photon purity confirmed with g^{(2)}(0) of 0.141 ± 0.027.

Abstract

Non-classical photon sources made of semiconductor quantum dots (QDs) emitting in the telecommunication C-band are crucial components for low-loss, long-distance photonic quantum communication networks. Here we designed and fabricated strain--free In$_{0.7}$Ga$_{0.3}$As/In$_{0.7}$Al$_{0.3}$As QDs grown on GaAs(111)A substrates working as single-photon emitters in the 1550 nm window. The QDs were grown via local droplet etching method in a molecular beam epitaxy environment, employing a thin In$_{0.7}$Al$_{0.3}$As metamorphic buffer layer with the same lattice constant of the QD material, thus allowing for a completely strain--free self-assembly of the QDs. The QDs exhibit a C$_{3v}$ symmetry with a ground state emission in the 1400--1600 nm range. The exciton lifetimes of $\approx$ 1.3--1.9 ns and linewidths as low as $\approx$ 300 $\mu$eV show the good quality of the fabricated QDs. Second-order autocorrelation measurements under pulsed excitation confirmed the single-photon purity of the emitters, yielding a $g^{(2)}(0)$ value of $0.141 \pm 0.027$