Description du sujet de thèse

The aim of this thesis project is to develop single photon sources emitting at 1.55 µm from InAs quantum dots obtained by selective epitaxy on an InP substrate. It will involve the growth and morphological and optical characterisation of the quantum dots and the development of high quality factor Bragg mirrors on an InP substrate for ultra-bright photon sources.
Although this technology exists for the GaAs/AlAs material system, sources on GaAs substrates cannot emit at 1.55 μm, a wavelength that is very important for fiber quantum communications and applications such as quantum key distribution, quantum cryptography and distributed quantum computing. Until now, obtaining very pure and indistinguishable single photons at 1.55 μm has been limited to frequency conversion or the use of MoTe2, but the results in terms of indistinguishability and brilliance remain limited. Thanks to the progress made in recent years at IEMN in the nanofabrication of masks for selective area epitaxy, it is now possible to envisage the definition of a silicon oxide mask with apertures with a diameter of less than 30 nm. In addition, the selective epitaxy of III-V semiconductors demonstrated by the EPIPHY group for the growth of planar nanowires [1] could be used to grow InAs boxes in these nanometric openings. With regard to Bragg mirror epitaxy, the PhD student will benefit from the arrival in 2025 of a new growth reactor equipped with a system for precisely controlling the composition of the alloys by measuring in real time the curvature of the substrate caused by the stresses in the epitaxial layer.
Thanks to the deterministic nature of this technology, which enables the quantum dots to be precisely located on the surface of the substrate, we hope to significantly improve the yield and integration possibilities of these sources, while achieving ultra-high single-photon emission rates that exceed the 17% extraction efficiency found in the literature.
During his/her thesis, the candidate will be trained in various nanofabrication technologies, including molecular beam epitaxy and electron lithography, as well as various morphological (AFM), structural (XRD) and optical (PL) characterization techniques, enabling him/her to demonstrate the emission of single photons by quantum dots.
During his/her thesis, the candidate will be trained in various nanofabrication technologies, including molecular beam epitaxy and electron lithography, as well as various morphological (AFM), structural (XRD) and optical (PL) characterization techniques, enabling him/her to demonstrate the emission of single photons by quantum dots.
References :
[1] Desplanque et al 2018 Nanotechnology 29 305705

Contexte de travail

The work will be performed at the Institut d'Electronique de Microélectronique et de Nanotechnologie (IEMN) located in Villeneuve-d'Ascq near Lille in the Hauts-de-France region. IEMN is a research laboratory bringing together 500 people (professors, international researchers, engineers, technicians and students) from the CNRS, the University of Lille, the Polytechnique Hauts de France University and the Centrale Lille and Junia-ISEN engineering schools. The laboratory focuses on micro and nanotechnologies and their applications in the fields of information, communication, transport and health. Our researchers have access to exceptional experimental resources, in particular technological and characterization resources whose capacities and performance are at the highest European level.
The PhD candidate will be co-supervised by an expert in epitaxy and nanodevice fabrication [2], an expert in quantum phenomena and optical characterisation [3] and an expert in near-field characterisation and quantum materials [4]. This training objective aims to develop the PhD candidate's skills in the field of quantum technologies, both in terms of engineering and physics. Collaboration with the Jülich Research Centre in Germany will also be possible to study the structural properties of epitaxial materials using transmission electron microscopy.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

A large part of the activity will be performed in clean room.