Description du sujet de thèse

The proposed PhD aim to contribute to a collaborative project to develop the next-generation of betavoltaic (BV) energy sources. These devices are of increasing interest due to their potential to deliver long-lasting, maintenance-free power in extreme and remote environments, where conventional batteries or solar panels fail to meet operational requirements. Betavoltaic systems harness the kinetic energy of β-particles (electrons or positrons emitted by a radioisotope) and convert it into electrical energy through interactions within a semiconductor material—analogous to the photovoltaic effect observed in solar cells. The key advantage of BV generators lies in their exceptional operational longevity, which is governed by the half-life of the radioactive source rather than external environmental factors. This makes them highly durable, compact, and reliable for use in applications such as space exploration, structural health monitoring, biomedical implants, and defense systems.
However, the current generation of commercially available BV devices suffers from limited energy conversion efficiency due to their planar semiconductor architecture. These planar structures present constraints in optimizing both the absorption of β-particles and the efficient collection of generated charge carriers, leading to suboptimal performance. This PhD project proposes a transformative approach to overcome these limitations through the design, fabrication, and characterization of core-shell nanowire p-i-n junctions using wide-bandgap semiconductors such as gallium nitride (GaN) and aluminum gallium nitride (AlGaN).
The core-shell nanowire geometry presents a unique opportunity to decouple the paths of β-particle absorption and carrier collection. By leveraging radial heterostructures, the project aims to enhance carrier separation and collection efficiency while increasing the effective surface area for energy conversion without significantly increasing device footprint. GaN-based materials are particularly well-suited for this application due to their radiation hardness, thermal stability, and favorable electronic properties. The project will explore advanced growth techniques at CEA IRIG (e.g., molecular beam epitaxy or metal-organic chemical vapor deposition), nanofabrication strategies at Néel Institute, and detailed modeling of β-particle transport and energy deposition in complex nanostructured geometries.

Contexte de travail

The Institut NEEL, UPR 2940 CNRS, is one of the largest French national research institutes for fundamental research in condensed matter physics, enriched by interdisciplinary activities at the interfaces with chemistry, engineering and biology. The laboratory is attached to CNRS Physics. It is located at the heart of a unique scientific, industrial and cultural environment. It is part of one of Europe's largest high-tech environments for micro and nanoelectronics, right next to the French Alps.
Within the Institut Néel, the SC2G team specializes in the experimental study of wide band gap electronic and optoelectronic devices.
The NEEL Institute is a CNRS laboratory. The CNRS is a public scientific and technological establishment. Its mission is to identify, carry out or commission, alone or with its partners, all research of interest to the advancement of science and to economic, social and cultural progress. Internationally recognised for the excellence of its scientific work, the CNRS is a benchmark both in the world of research and development and for the general public.

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.

Informations complémentaires

PLUM Department