Xenon plasma-focused ion beam milling as a method to deterministically fabricate bright and high-purity single-photon sources operating at C-band

TL;DR

This paper introduces Xenon plasma-focused ion beam milling as a novel 3D nanofabrication method for creating high-purity, high-efficiency single-photon sources at C-band, outperforming traditional electron beam lithography.

Contribution

It demonstrates a new 3D shaping technique using Xe-PFIB for photonic nanostructures with quantum dots, enabling improved photon extraction efficiency and purity.

Findings

Achieved photon extraction efficiency of 0.89 with FDTD simulations.

Demonstrated 99% purity of pulsed single-photon emission.

Surpassed previous electron beam lithography performance in the C-band.

Abstract

Electron beam lithography is a standard method for fabricating photonic nanostructures around semiconductor quantum dots (QDs), which are crucial for efficient single and indistinguishable photon sources in quantum information processing. However, this technique lacks direct 3D control over the nanostructure shape, complicating the design and enlarging the 2D footprint to suppress in-plane photon leakage while directing photons into the collecting lens aperture. Here, we present an alternative approach to employ Xenon plasma-focused ion beam (Xe-PFIB) technology as a reliable method for the 3D shaping of photonic nanostructures containing low-density self-assembled InAs/InP quantum dots emitting in the C-band range of the 3rd telecommunication window. We explore both deterministic and non-deterministic fabrication approaches, resulting in mesas naturally shaped as truncated cones. As a demonstration, we fabricate mesas using a heterogeneously integrated structure with a QDs membrane atop an aluminum mirror and silicon substrate. Finite-difference time-domain (FDTD) simulations show that the angled sidewalls significantly increase photon extraction efficiency, achieving {\eta} = 0.89 for NA = 0.65. We demonstrate experimentally a high purity of pulsed single-photon emission (~99%) and a high extraction efficiency of {\eta} = 0.24, with the latter surpassing the highest reported values obtained using electron beam lithography in the C-band.