Context
An increasing number of flat-glass applications involve functionalization of the glass surface obtained by depositing a series of thin films (on the order of 10 - 100 nm in thickness) on the surface of the glass by PVD magnetron sputtering. We can cite, for example, low emissivity (insulating) windows, anti-reflective glazing, smart windows or solar control windshields. Nanostructuring of these films opens the new possibility to control surface properties like adhesion, wettability, wear or hydrophobia, and to provide new functionalities such as self-cleaning, anti-fouling, anti-bacterial, thermoregulation or controlled reflectivity. The laser engineering of surfaces has been growing fast for about two decades. A flexible, rapid and cost-effective approach to nanostructure surfaces is based on scanning lasers and self-organization mechanisms. These mechanisms can create periodic surface structures whose properties depend on several parameters of the material and laser processing, and can find different physical origins1 .
Subject of the thesis
The objective of this thesis is to investigate local phase transformations and surface nanostructuring induced by laser on metal-oxide and nitride thin films and to study their effect on the film properties. Different laser wavelengths, pulse durations, fluences, repetition rates and polarizations will be considered as well as various film thicknesses or stoichiometries. Time-resolved pumpprobe characterizations will be carried out to follow the kinetics of laser-induced crystallization. Post mortem characterizations, such as Raman microspectroscopy, atomic force microscopy, scanning and transmission electron microscopy, will be used to identify the spatial distributions of the phase changes at the nano- and micrometer scales2 . The experimental work will be supported by theoretical modelling of the basic mechanisms involved in such laser-induced transformations. With this study, we expect new surface properties of the films, which could be implemented on large areas or controlled at the micrometer scale. TiO2 thin films will be investigated as a first step, as the stoichiometry can be easily tuned from an absorbing metal to a transparent oxide. Then, the developed approach will be extended to titanium nitride
Two laboratories associate in this work:
• Saint-Gobain Research Paris through the team Surface du Verre et Interfaces, expert in glass and thin film manufacturing, material characterization and modelling.
• Hubert Curien Laboratory, expert in laser - matter interaction, optical and material characterization, and electromagnetic modelling.
The working time will be equally shared between the two laboratories, implying a significant number of journeys for the PhD student.
Considered experimental techniques
Ultrafast laser, time-resolved pump-probe spectroscopy, thin film preparation, laser-matter interactions, surface and material characterization techniques, physico-chemical modelling.
Candidate profile
This experimental PhD project is suitable for applicants graduated with a master or an engineering degree in physics, nanophotonics, photonics, optics or related topics. Good level in English is required. The PhD candidate should be interested in material science and have a strong motivation to answer the most important questions of the fundamental laser-induced physics and chemistry of thin films. He (she) should have a solid background in physics to carry out experimental research using and developing ultrafast laser instrumentation, spectroscopy, microscopy, and data analysis. The ability to take initiatives and to work with autonomy is compulsory to carry out this thesis, while relying on the skills of the different people involved in the project. Good communication and writing skills are also required to enable efficient communication between the two teams supervising the PhD work based in two different towns.
Application
Applications must be sent to all contact email addresses as soon as possible and before May 10th, 2021.
Application can be written in French or in English.
All applications must contain:
• a CV, with a possible list of publications and conferences, and the CEFR level in English (except if university courses were taught in English)
• a short motivation letter explaining why you should be successful in this research work
• Bachelor degree and transcripts
• Master transcripts (at least semester 1 and 2. Semester 3 if available)
• References of academics to be contacted (or recommendation letters).
Contacts
At Saint Gobain Research Paris:
• Ekaterina Burov : ekaterina.burov@saint-gobain.com
• Matteo Balestrieri : matteo.balestrieri@saint-gobain.com
• Iryna Gozhyk : iryna.gozhyk@saint-gobain.com
• Maria Malheiro Reymao : maria.malheiroreymao@saint-gobain.com
At Laboratoire Hubert Curien:
• Prof. Nathalie Destouches : nathalie.destouches@univ-st-etienne.fr