POST-DOC: Ferroelectric control of superconducting 2-dimensional electron gases (M/F)

Job Description

Missions

Develop field-effect transistors combining a KTaO3-based two-dimensional electron gas (2DEG) with a HfZrO2 (HZO) ferroelectric gate. The project aims to achieve nonvolatile control of the electronic properties of the 2DEG through ferroelectric polarization while preserving the quality of the conducting interface.
The successful candidate will investigate the relationship between polarization, carrier density and mobility, then explore control of the superconducting state in heterostructures that remain superconducting after gate integration.

Activity

• Grow HZO thin films by atomic layer deposition (ALD) and/or pulsed laser deposition (PLD). Optimize deposition conditions, annealing and electrode materials to obtain switchable polarization while preserving the 2DEG.
• Characterize heterostructure structure, morphology and composition using X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy.
• Fabricate capacitors and transistors in the cleanroom using optical and/or electron-beam lithography, electrode deposition and etching.
• Measure ferroelectric properties using polarization loops, positive-up-negative-down (PUND) protocols and piezoresponse force microscopy. Assess retention and endurance and distinguish ferroelectric switching from charge trapping or ionic migration.
• Perform resistance and Hall measurements before and after gate integration, then following voltage pulses, with readout at zero gate voltage.
• Explore at low temperature how the critical temperature and, where accessible, the superconductor-insulator transition depend on polarization and KTaO3 orientation.
• Analyze data, document experimental protocols and write scientific publications. Present results to project partners and at conferences.

Your Profil

Skills

• Strong background in condensed matter physics and thin-film electronic devices.
• Experimental experience in oxide thin-film growth, particularly ALD or PLD. Experience with hafnia-based ferroelectrics would be particularly valuable.
• Knowledge of structural characterization methods and electrical measurements of ferroelectrics. Experience with PUND protocols or piezoresponse force microscopy would be an asset.
• Experience in cleanroom microfabrication and optical or electron-beam lithography is desirable.
• Skills in electronic transport, Hall measurements and low-temperature experiments are desirable. Knowledge of oxide 2DEGs or superconductivity would be an asset.
• Proficiency in data analysis and scientific programming, particularly Python. Experience in measurement automation, for example using LabVIEW, is desirable.
• Experimental rigor, independence and the ability to work within a team. Good scientific writing and communication skills in English.

Your Work Environment

The position is based at Laboratoire Albert Fert (CNRS, Thales, Université Paris-Saclay) in Palaiseau, within the Oxitronics team, under the supervision of Manuel Bibes. The project combines ferroelectricity, oxide interface physics and two-dimensional superconductivity.
The successful candidate will work with the laboratory's researchers, engineers and PhD students and have access to thin-film growth, characterization and microfabrication facilities. Measurements at very low temperatures will be conducted in collaboration with Nicolas Bergeal at ESPCI Paris. Comparisons between KTaO3 (111), (110) and (001) will enable investigation of the role of crystal orientation.

Constraints and risks

• Experimental work involving vacuum deposition equipment, thermal treatments and cleanroom processes.
• Use of chemicals and deposition precursors in accordance with safety procedures and following the required training.
• Measurements under magnetic fields and at cryogenic temperatures, subject to the safety procedures of the relevant facilities.
• Careful documentation of fabrication processes, reproducible measurements and control of interface quality are essential.

Compensation and benefits

Compensation

3131,32 to 3569,85€ gross per month

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions