Missions

The recruited candidate will carry out fabrication processes in a cleanroom and characterization experiments in the infrared on laser devices and detectors. Depending on their profile, they will also contribute to their design using electromagnetic modeling tools for photonic devices. They will participate in meetings with national and international partners and contribute to the dissemination and promotion of results through international research conferences and publications in peer-reviewed journals.

Activités

The postdoctoral researcher will conduct initial studies on the design and development of devices for normal-incidence detection on an active layer deposited on a silicon substrate. Approaches leveraging optical field enhancement through electromagnetic resonance will be explored using vertical cavity Metal-Semiconductor-Metal (MIM) structures. Initial experimental demonstrators will be fabricated using the micro-nano-fabrication facilities at C2N.

A second focus will involve the integration of such detectors with laser sources based on microdisk, ring, and photonic crystal cavity designs. There is also strong interest in GeSn due to its potential for achieving a direct bandgap alignment, enabling optical gain in a laser—something that is not possible with Ge, Si, or SiGe alloys.
The C2N team has been conducting research for several years to develop silicon-compatible laser sources by alloying Ge with Sn and using strain engineering to optimize the band structure and optical gain properties. This low-cost laser technology has only recently emerged (with the first publication in 2015 reporting lasing at temperatures below 100 K), thanks to the use of GeSn alloys and tensile strain engineering.
In a previous project supported by the IPCEI-Nano 2022 initiative in collaboration with STMicroelectronics, the C2N team demonstrated, for the first time, laser operation up to room temperature (300 K). To achieve this, a specific transfer technology for the GeSn active layer onto an insulating substrate (GeSnOI) was employed and will also be utilized in this project.
New opportunities have now emerged with the recent development of GeSn-based quantum well structures, which will be further explored in this project.

Compétences

Skills in cleanroom micro-nanofabrication are appreciated, as well as experience in the characterization of photonic devices in the infrared.

Contexte de travail

The ambition of the project is to provide a fundamental technological building block for infrared detection and imaging based on GeSn, a semiconductor material compatible with the low-cost manufacturing processes of the silicon industry. GeSn offers a reduced bandgap energy compared to Si and Ge, making it an attractive candidate for infrared applications.
Leveraging GeSn alloys, the demonstrators will focus on infrared detection in the 2 µm–5 µm wavelength range, which cannot currently be covered by the silicon technology platform (Si, Ge, SiGe). This will enable laboratory-on-chip spectroscopy applications with the potential to integrate all Group IV photonic circuits into interconnected devices.
Achieving this goal requires the development of low-cost components operating in the 2–5 µm infrared range, which is currently only accessible through expensive niche technologies, such as those based on antimonide compounds (InSb, GaSb, etc.). In contrast, a technology based on GeSn compounds would represent a major breakthrough and a decisive advantage for the rapidly growing field of silicon photonics.
This technology is expected to expand low-cost detection capabilities, enabling large-scale deployment in portable devices. The development of GeSn materials will be carried out in collaboration with existing partners of C2N, including CEA (France), Juelich (Germany), and UARK (USA).

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.

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

Chemical hazard and cleanroom safety training must be completed upon arrival at the laboratory.