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Subject of the Master's internship

Growth of High Quality 2D Hexagonal Boron Nitride on a Liquid Metal Catalyst

Descriptif en français. Internship may to be followed by a PhD-thesis on the same subject
Published on 14 September 2022
The CEA and CNRS are major French research agencies. IRIG and Institut Néel are two of their institutes devoted to fundamental research in the Grenoble Minatec ( area. The European Synchrotron ESRF is a multinational research institute situated in Grenoble, which operates one of the most powerful synchrotron X-ray sources. It offers a highly dynamic, exciting, and multinational working environment in the French Alps. As part of a collaborative research project, we propose for the 2022-2023 academic year.

The subjet
Two-dimensional (2D) materials are one or few atom thick crystals with high stability and physical properties governed by extreme quantum confinement. With its unique crystalline structure, graphene exhibits a plethora of unconventional electronic phenomena, whose exploration was awarded the 2010 Nobel Prize in Physics. Graphene is part of a larger family of 2D materials: one of its cousins, hexagonal boron nitride (h-BN), shares the same crystal lattice but exhibits different properties. For example, it is a wide band-gap semiconductor that can serve as a hyperbolic material in the infrared, and it hosts defects relevant to engineer quantum sources of light. Additionally, it turns out to be the ideal material to encapsulate more fragile 2D materials. This allows preserving their properties and building artificial multi-functional materials consisting of stacks of 2D materials.
Despite these attributes, the widespread development of 2D h-BN faces a significant challenge: it is still difficult to control its thickness and structural quality over large scales. One solution to this problem is to finely control the synthesis of the material from the bottom-up, i.e., to assemble the atomic building blocks one by one and grow the largest possible single crystal this way. The most promising method is chemical vapor deposition (CVD), in which a fine control of the experimental conditions via the temperature and the precursor vapor pressures is needed. We recently achieved the CVD growth of graphene of the highest quality and over large areas by using liquid instead of solid metal as both substrate and catalyst of the precursor decomposition. This was made possible by finely monitoring the growth, realized in situ and in real-time, using three complementary techniques (optical microscopy, Raman spectrometry, synchrotron X-ray diffraction), allowed by our home-built state-of-the-art reactor, and real-time feedback on the growth parameters (see and Jankowski et al, ACS Nano 2021, 15, 9638−9648).
In this work, we propose to apply the same approach to the growth of 2D h-BN. As a result, we expect a very significant improvement in the structural quality and size of the grown material.
Beyond the unique physics of 2D growth at the heart of the Ph.D. thesis, the work connects with our local collaborators, on the one hand addressing the exceptional optical properties of the material and on the other hand using the produced h-BN to build 2D stacks of much improved properties.

The work and working environment
The experimental work will be performed at a dedicated laboratory located at the ESRF, hosting a CVD reactor with associated in situ characterization tools: emission mode optical microscopy, Raman spectroscopy, and synchrotron X-ray scattering and reflectivity. You will work with the ESRF local team, in close connection with two external teams, one from CNRS/Institut Néel and one from CEA/IRIG.
First, you will find the experimental conditions to grow h-BN on liquid metals. These will be analyzed at different length scales from nanometric to macroscopic and over different time scales in relation to experimental conditions (temperature, reactive gas pressure, and fluxes). Then, the results will be interpreted in close collaboration with theoreticians. In a later stage, you will be involved in transferring the h-BN layers on other substrates or 2D materials and performing experiments to investigate (in collaboration) some of their physical properties.

Qualifications ans experience
You should hold a Master degree in Physics, Chemistry, Materials Science, Nanoscience, or closely related. Interest in the field of liquids/soft matter and growth of materials would be an asset.
You should be motivated by experimental work, data acquisition and analysis, and possibly by developing analysis programs.

In addition, you should have:
· Ability to get to the heart of the problem and take it effectively through to completion;
· Self-motivation and initiative attitude;
· Good interpersonal, communication, and presentational skills;
· Good organizational and planning skills;
· Will to work as part of a multi-disciplinary team.

We expect the Master 2 internship to be followed by a PhD-thesis on the same subject.

The internship is expected to start in spring 2023 for a minimum duration of four months
Interested applicants should submit:
- A 1-page letter stating motivations,
- A curriculum vitae, and
- Contact information for 2 references (reference letters are not required at this time)
to Maciej Jankowski, Johann Corau and Gilles Renau.

Before the application deadline of January 15, 2023.

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