Place : 1 avenue Augustin-Fresnel, 91767 Palaiseau, France
Manager : Manuel BIBES, manuel.bibes@cnrs-thales.fr
Scientific Context
Ferroelectrics are polar materials whose switchable polarization can be used to store non-volatile information. Among them, BaTiO₃ (BTO) stands out for its low-voltage switching and high endurance in thin-film form. Remarkably, BTO can also become conducting when doped with electrons, leading to a rare coexistence of ferroelectricity and metallicity. This unconventional combination raises key questions: how do structural distortions, carrier density, and electrostatic screening interact at the nanoscale? How does this balance evolve with film thickness, doping level, or epitaxial strain? Beyond fundamental interest, creating a 2D conducting channel – either a two-dimensional electron gas (2DEG) or a lightly
doped polar metal – within the same ferroelectric matrix offers a new route to mitigate interface defects that limit the performance of ferroelectric field-effect transistors (FeFETs).
Work program & skills acquired during internship
The goal of the internship is to grow epitaxial BaTiO3 films by hybrid molecular beam epitaxy (MBE), a technique enabling atomic-scale control and the highest material quality. The intern will:
- Learn and assist in the operation of the hybrid-MBE system to deposit BTO and SrRuO3 bottom electrodes;
- Characterize films using X-ray diffraction, atomic-force microscopy, pizeoresponse-force microscopy and electrical measurements;
- Generate and study ultrathin conducting layers in BTO, either by controlled La doping or by inducing a 2DEG at the surface;
- Fabricate SRO/BTO/SRO capacitors and measure ferroelectric properties (switching voltage, endurance, retention);
- Use conducting BTO layers as channels for FeFETs, and analyze their transport characteristics.
This internship will provide strong hands-on experience in thin-film growth, advanced characterization, and device physics. Depending on progress, it can be extended into a PhD thesis focusing on the physics and applications of ferroelectric-metallic oxides.
Work environment
You will work at C2N with Thomas Maroutian for film growth, and at the Laboratoire Albert Fert with Manuel Bibes for ferroelectric characterization and device studies.