After a bachelor’s degree in Physics and Technology in Nantes, Baptiste Gonon-Mathieu continued at École Polytechnique in Palaiseau, where he followed a general engineering curriculum with a focus on Energy and Electronics. He later specialized in satellite design at ISAE-SUPAERO in Toulouse and joined the French Ministry of Defence procurement agency (DGA) before deciding to pursue a PhD at the intersection of physics and electronics at CEA-Leti’s cooled infrared imaging laboratory.

His doctoral work centers on electron transport in superlattices used for infrared detectors. These structures are built by stacking nanometer-thick layers of two semiconductors, InAs and InAsSb, to absorb infrared radiation. Because researchers believe these materials are highly anisotropic — meaning their properties vary depending on direction — a major challenge is to understand how electrons actually move through them and to develop reliable measurement methods for future infrared sensors.

Baptiste adapted an EBIC-based method to etched samples, allowing him to separate vertical and lateral electron transport and analyze the results with 3D models. Unlike surface-only observations, his approach also probes the material in depth. The work, published in the Journal of Electronic Materials and presented at the II-VI Workshop in Chicago, is described as one of the first direct experiments in the literature to quantify this anisotropy.

The measurements showed an anisotropy of about 2.7, notably lower than expected. That matters because anisotropy directly affects infrared sensor performance: electrons must be collected at the right place to form a sharp image, and excessive lateral movement can blur the result. The finding therefore has practical implications for the design of next-generation infrared detectors.

This was Baptiste’s first international conference, an important milestone in a relatively small research community where scientists know one another well and young researchers need to establish visibility. His PhD is carried out in collaboration with Lynred, the laboratory’s industrial partner, with the goal of better understanding superlattice behavior and supporting the development of new infrared sensors.

The broader significance is technological as well as industrial. Infrared detectors have historically relied on II-VI materials, while superlattices belong to the more recent III-V semiconductor family and are seen as a promising route toward more stable infrared sensors. Infrared imaging has wide applications in defense, industry, and science, including surveillance and Earth observation, and this research feeds directly into Lynred’s R&D efforts as a major French player in infrared sensors.

News|Headlines|Success|Nomination|Profile

After completing a bachelor program in Physics and Technology in Nantes, France, Baptiste began his engineering studies at École Polytechnique (Palaiseau, France), where he followed a general engineering curriculum with a focus on Energy and Electronics. He then specialized in satellite design at ISAE-SUPAERO (Toulouse, France) and joined the French Ministry of Defence procurement agency (DGA).

It was during this time that he decided to pursue a PhD at the crossroads of physics and electronics, within CEA-Leti's cooled infrared imaging laboratory.

His research focuses on electron transport in the superlattices used in infrared detectors. These novel materials, made by repeatedly stacking nanometer-scale layers of two different semiconductors, InAs and InAsSb[1], enable infrared radiation to be absorbed.

Researchers suspect that these materials are highly anisotropic, meaning that their properties differ depending on the direction in which they are measured. The goal is therefore to understand how electrons actually move within these structures. Developing robust measurement methods is a key challenge in the development of future infrared sensors.

Baptiste adapted this method to etched samples in order to decouple the vertical and horizontal motion of electrons, and then analyzed the observations using 3D models. The distinctive feature of his approach is that observations are no longer limited to the surface but can also be performed in depth.

The results were published in the Journal of Electronic Materials and presented at the II-VI Workshop in Chicago. The paper describes a new method for measuring anisotropy using EBIC. It represents one of the first direct experiments reported in the literature to quantify this anisotropy.

Measurements of the lateral and vertical movement of charges revealed an anisotropy of approximately 2.7, significantly lower than expected. This result is particularly important because anisotropy is a key parameter determining infrared sensor performance.

Electrons must be collected at the right location to produce a sharp image. If they move too far laterally due to anisotropy, the resulting image becomes blurred.

For the PhD student, this international conference was a first. The infrared research community is relatively small, and researchers know one another well, making it important for young scientists to establish themselves.

This research is being conducted in collaboration with Lynred, as an industrial partner of the laboratory. The aim is to gain a deeper understanding of the behavior of superlattices in order to develop new infrared sensors.

Historically, infrared detectors have relied on II-VI materials. Superlattices, on the other hand, belong to the III-V semiconductor family, a more recent technology platform that holds promise for more stable infrared sensors.

Infrared imaging has applications across defense, industry, and science, including surveillance and Earth observation.

This research directly contributes to the R&D activities of Lynred, a key French player in the field of infrared sensors.

[1] InAs (indium arsenide) and InAsSb (indium arsenide-antimonide) are semiconductor materials belonging to the III-V semiconductor family.​

EBIC Characterization of Vertical Transport of Minority Carriers in Gallium-Free Type-II Superlattices for Infrared Detectors(https://doi.org/10.1007/s11664-026-12938-3)

Learn more about the conference:https://www.ii-viworkshop.org/

Learn more about Baptiste's PhD research:Link to PhD videohttps://www.youtube.com/shorts/cSxHQfSfGyk​​​