Researchers Look to Develop a Method for Mass Adoption of Graphene

August 05, 2021 by Ahmad Ezzeddine

Several research groups look to control the growth of graphene with the use of synchrotron x-ray diffraction, synchrotron x-ray reflectivity, Raman spectroscopy, and radiation-mode optical microscopy.

A European research team has recently released their findings on the real-time multiscale monitoring and tailoring of the growth of graphene on liquid copper.

An illustration of the experimental setup, in situ microscopy, and Raman mapping on the layer.  Image courtesy of ACS nano.

Graphene has a thin hexagonal arrangement of carbon. Due to this arrangement graphene has a high electrical conductivity property. Therefore, graphene is expected to be a major material used in several applications ranging from the biomedical industry into energy and electronic manufacturing industries and more.

The experiment needed a specific setup to ensure the growth of graphene on liquid copper. Also, specific observation methods were used.


Experimental Setup

The researchers used this setup to perform the experiment:

  1. A cylindrical-shaped reactor.
  2. An X-ray transparent beryllium wall.
  3. A quartz window is needed in order to monitor the process.
  4. A heater that could provide temperatures up to 1600 K.
  5. A tungsten disk to place the heater in contact with the reactor.
  6. A gas handling system that delivers a mixture of reactant gases to the reactor after mixing them.


Graphene Growth on Liquid Copper

To form the liquid copper, the researcher molted ultrapure foils of copper after adding them to the sample holder.

Then the researchers used chemical vapor deposition to grow a graphene layer on top of the liquid copper. Therefore, a CH4 is pressurized toward the liquid copper and dissociated catalytically, releasing a graphene layer on top of the liquid copper.


Observation Methods

To monitor the process the researchers used three observation methods:

  1. Raman Spectroscopy: The researchers used Raman spectroscopy in order to characterize the growth of graphene on the liquid copper. It is used to monitor the defect density, number of graphene layers, and stacking type.
  2. X-ray Based Measurement: The X-ray measurement provides an out-of-plane density profile in which the researchers deduced a low roughness rate in the graphene layer.
  3. Optical Microscopy: A digital optical microscope that can record a 30 fps video with a high resolution was used to observe and record various growth conditions of graphene. The microscope recorded only light radiated from the sample. Therefore, researchers observed the difference between graphene and liquid copper.

The researchers: Maciej Jankowski, Mehdi Saedi, Francesco La Porta, Anastasios C. Manikas, Christos Tsakonas, Juan S. Cingolani, Mie Andersen, Marc de Voogd, Gertjan J. C. van Baarle, Karsten Reuter, Costas Galiotis, Gilles Renaud, Oleg V. Konovalov, and Irene M. N. Groot contributed to completing the practical methods for synthesis of defectless two-dimensional materials such as graphene.

This project (LMCat) has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement 736299. Some research leading to this publication has been supported by the project CALIPSOplus under Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020.