In situ investigation and operando monitoring of graphene growth on liquid copper

Start Date
06-02-2020 10:00
End Date
06-02-2020 11:00
Room 337, Central Building
Speaker's name
Speaker's institute
CEA Grenoble
Contact name
Eva Jahn
Host name
Oleg Konovalov
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Two-dimensional materials (2DMs) are at the center of attention due to their unique electronic, mechanical, thermal, and optical properties. The chemical vapor deposition (CVD) growth of 2DMs on liquid metals is an emerging and promising route towards the controlled fabrication of high-quality 2DMs, not achievable on solid substrates.  However, gaining insight into fundamental processes occurring on liquid metals during growth was up to now challenging, even impossible, due to harsh prevailing conditions inside CVD reactors excluding most experimental methods.

Graphene (Gr) is a prototypical 2D material, which synthesis generally relies on CVD growth on solid substrates, mainly copper. Despite recent progress and fine-tuning of growth procedures, there are significant obstacles in transferring the current knowledge towards the mass production of good quality sheets over large-scales. The main showstoppers are slow procedures of 2DMs separation from solids, their environmental unfriendliness, and low quality of produced layers. All of these factors significantly affect process costs, speed, and waste production.

The primary purpose of this contribution is to present the first experimental results of Gr growth on liquid copper in a newly developed CVD reactor, dedicated to the study of chemical reactions on liquid metal catalysts (LMCats). By combining in situ surfaces X-ray diffraction (SXRD) and optical microscopy, supported by ex situ Raman spectroscopy, it is possible to resolve in real-time the growth dynamics and atomic structure of graphene during its growth on liquid copper. Contrary to solid surfaces, this later is an atomically smooth, isotropic and mobile medium, which allows producing graphene crystals of high-quality and large sizes limited only by the size of the liquid bath surface. A myriad of intriguing growth scenarios was observed which allowed to fine-tune the fabrication procedures and to identify critical factors affecting the growth of individual flakes, their self-assembly and further association into a single layer with a coherent atomic structure.  These findings open new possibilities for the growth of 2D materials with unprecedented control over growth kinetics, hardly achievable by any method up to now.

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