PhD position / Thèse CIFRE

Topic: Selective growth and optical spectroscopy of carbon nanotubes for quantum technologies between Laboratoire Charles Coulomb (L2C), Université de Montpellier & CNRS, Montpellier & C12 Quantum Electronics.

Carbon nanotubes (CNT) represent a fascinating class of one-dimensional crystals, characterized by a very high aspect ratio (diameter of the order of 1 nm for typical lengths of 1 to 1000 µm). They feature several possible crystal structures (also known as chiralities) varying in diameter and chiral angle and described by a pair of indices (n,m) called Hamada indices. In terms of electronic transport, carbon nanotubes can be either metallic (if n-m is a multiple of 3) or semiconducting (if n-m is not a multiple of 3), and exhibit ballistic transport at room temperature.

As a consequence of their one-dimensional nature, their optical properties are also remarkable, with absorption at precise energies characteristic of each chirality. However, despite their extraordinary potential, a major challenge remains: precise control of the structure of carbon nanotubes remains elusive during their growth. CNT growth is based on a catalyst-assisted chemical vapor deposition (CVD) process. In this process, metal nanoparticles act both as growth catalysts and as templates for the formation of nanotubes with diameters close to 1-3 nm. Under standard conditions, there is little or no structural selectivity. For quantum technologies applications, another challenge arises from the formation of defects and amorphous carbon clusters along the CNT length, suspected of being largely responsible for the yield reduction of functional CNT-based devices.

The recruited PhD student will develop novel CVD growth methods with high selectivity for specific types of nanotubes, ultralow defect density and ultralow contamination level, using local electric field and methane-based gas mixtures, for the purpose of integrating them into quantum devices. To sustain these developments, he/she will develop metrology protocols based on advanced optical spectroscopy techniques and high-resolution transmission electron microscopy. Ultimately, the results of the developments will be validated by the electronic transport signature of the grown CNTs embedded in circuits, known to be sensitive to the lowest number of defects, at room and cryogenic temperatures.

The PhD student will be part of a project team made up of researchers and engineers from the Charles Coulomb laboratory, internationally renowned in the field of carbon nanotubes, and the high-tech company C12, at the forefront of the development of new quantum computers.

• An applied research project involving a strong partnership between an academic research laboratory based in Montpellier and an innovative company in the heart of Paris.
• Access to state-of-the-art nanoscience research equipment and training in investigative methods mastered by just a few teams worldwide: growth of individual and suspended carbon nanotubes, resonance Raman spectroscopy, resonant Rayleigh scattering spectroscopy, cleanroom for nanofabrication, cryostats for electronic transport measurement.
• Participation in international conferences and the international summer school we organize every two years on the optical properties of low-dimensional systems.
• Our network of national and international collaborations with both academic and industrial partners.
• Optimal working conditions in fully renovated research buildings at the heart of the University of Montpellier's science campus.
• At the end of the PhD, significant recruitment opportunities over the next ten years, both in the academic sector (due to numerous retirements within universities) and in the private sector (with the industrial development of carbon nanotubes).
• Contract type: CIFRE thesis
• Duration: 3 years

• Master's degree or engineering diploma in Chemistry, Physics or Materials Science by September 30, 2025
• Strong motivation for experimental research work
• Strong motivation for a research career, in academia or industry

• Thesis director is Pr Vincent Jourdain (Laboratoire Charles Coulomb, Montpellier) E-mail: vincent.jourdain@umontpellier.fr Profile: https://www.researchgate.net/profile/Vincent-Jourdain-2 Application
• If you would like to apply for this position, apply directly here or send your application (CV, motivation letter, contact details of 1-3 references) before May 15, 2025 to the following addresses: vincent.jourdain@umontpellier.fr or eileen@c12qe.com
• C12 Quantum Electronics
• Laboratoire Charles Coulomb
• University of Montpellier