2D materials: Silicene and beyond

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FLEURENCE Laboratory
Research Associate Professor：FLEURENCE, Antoine Gilles Valery

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［Research areas］
Applied Physics, Surface Sciences
［Keywords］
Nano and 2D materials, thin films, silicene, scanning tunneling microscopy

Skills and background we are looking for in prospective students　

The students need knowledge in solid state physics, which can also be acquired by students having a good capability of learning by themselves and curious. Skills in doing experimental work are required and it is better for the students to be good with their hands.

What you can expect to learn in this laboratory

Besides teaching them the scientific knowledge they need for their research, I tried to make students develop qualities which will be very useful in their future professional and personal life. By doing a cutting-edge research work and by performing difficult experiments autonomously, they learn how to carry out important projects autonomously. The analysis of the experimental results and the interpretation of their significance improve their critical thinking skills. Nevertheless, by talking frequently in English together about their research, the students become more and more confident in communicating in English.

Research outline

Owing to their flexibility, perfect smoothness and high surface sensitivity, two-dimensional (2D) materials which are thin films with a thickness down to a single atom, are promising for reducing further the dimensions of electronic components, to limit the heat dissipation in them and to allow for the fabrication of 2D devices which can be integrated in daily life items.

I have dedicated my current research to the fabrication and the study of 2D materials made of atoms from the same column as C in the periodic table and similar to graphene, a single layer of graphite. This research started few years ago with one of the very first reported experimental observation of silicene, done in our group. Silicene, as the ultimately thin form of silicon, has great expectation to allow for scaling down further the silicon-based nanotechnologies. For this purpose, many challenges need to be addressed: They are the objects of my current and future research.

1. We are investigating methods for tuning the electronic properties of silicene for instance by means atoms or molecules.
2. We try to find solutions to grow silicene on insulating or semiconducting substrates and to protect it from degradation in air.
3. We keep exploring the same column of the periodic table by trying to fabricate other 2D materials made of element like Ge or Sn.
4. We study the integration of silicene with other 2D materials.

Most of these experiments are done in ultra high vacuum (UHV) chambers in order to preserve these 2D materials from degradation. We characterize the 2D materials by means of surface sciences techniques including scanning tunneling microscopy (STM), a local probe technique capable of imaging the atomic structure of surfaces or 2D materials.Additionally, we perform experiments at synchrotron light source facilities in Japan and abroad aimed at determining the electronic properties of our 2D materials by angle-resolved photoemission spectroscopy (ARPES).

Key publications

1. Experimental evidence for epitaxial silicene on diboride thin films, A. Fleurence, et al., Phys. Rev. Lett. 108, 245501 (2012).
2. Insights into the spontaneous formation of silicene sheet on diboride thin films, A. Fleurence, and Y. Yamada-Takamura, Appl. Phys. Lett. 110, 041601 (2017).
3. Single-domain epitaxial silicene on diboride thin films A. Fleurence, et al., Appl. Phys. Lett. 108, 151902 (2016).

Equipment

• UHV system with STM at variable temperature, Low energy electron diffraction, Auger electron spectroscopy
• UHV system with STM, X-ray Photoemission spectroscopy
• UHV system for chemical vapor deposition of diboride
• Atomic force microscopy
• X-Ray diffractometer