XFab

an ERC Consolidator Grant

XFab is an ERC CoG 2017 grant (no. 776621) to Alessandro Molle carried out in the Agrate Unit of the CNR-IMM from 2018 to 2023. X stands for Xenes, monoelemental 2D-materials beyond graphene made of X atoms (silicene, germanene, stanene, etc.). Fab means production, process standardization, and device integration of the Xenes. XFab activity bridges the epitaxy of Xenes with the development of process schemes enabling Xene integration into devices in a wealth of nanotechnology fields (electronics, photonics, energy, etc.).

Related to XFab are the ERC PoC projects XMem and TNext.

The Xene Scenario

2D monoelemental crystals beyond graphene are an emerging branch that ranges from exfoliable flakes of phosphorene to epitaxial 2D lattices on substrate such as silicene. The latter subclass is usually referred to as Xenes with X initially denoting the group IVA semiconductors (Si, Ge, and Sn resulting in silicene, germanene, and stanene, respectively) and recently being extended to some elements in the group IIIA (e.g. B), VA (P,As,Sb,Bi), and VIA (Se,Te) of the Mendeleev table, other transition and nobel metals (Be, Mo, Au) . Different from graphene, #Xenes are epitaxially grown crystals with a buckled lattice structure. Epitaxy is the scalable path through which the Xenes are grown on suitable templates on large areas (up to cm2). More recently, chemical methods including the topotactic deintercalation and the liquid exfoliation, proved to be feasible approaches to massive production of Xenes.

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The Book of the Xenes

edited by Alessandro Molle & Carlo Grazianetti

This is the first full-comprehensive book of the Xenes. You can find the updated list of nowadays available Xenes, and all their relevant properties and applications. Available for purchase on the Elsevier website.

Outline

1. Silicene by E. Solomon, T. Angot, L. L. Y. Voon, and G. Le Lay

2. Germanene by H. J. W. Zandvliet

3. Stanene and Plumbene by A. Zhao

4. Borophene by B. Feng, L. Chen, and K. Wu

5. Gallenene by N. Gaston

6. Phosphorene by Y. Zheng, J. Gao, Y. Huang, T. Niu, and W. Chen

7. Arsenene and Antimonene by N. Antonatos, E. Kovalska, and Z. Sofer

8. Bismuthene by H. Zhao, S. Guo, W. Zhong, S. Zhang, L. Tao, and H. Zeng

9. Selenene and Tellurene by P.-Y. Lao, J. K. Qin, G. Qiu, Y. Wang, W. Wu, and P. Ye

10. Technical evolution for the identification of Xenes:

from microscopy to spectroscopy by M. Zhao, H. Feng, and Y. Du

11. Chemical methods for Xenes by W. L. B. Huey and J. E. Goldberger

12. Topological physics of Xenes by Y. Li, Z. Xu, Z. Zhang, J. Li, and Y. Xu

13. Optical properties of Xenes by P. Gore, F. Bechstedt, and O. Pulci

14. Two-dimensional magnetism in Xenes by A. M. Tokmachev, D. V. Averyanov,

I. S. Sokolov, A. N. Taldenkov, O. E. Parfenov, I. A. Karaten, and V. G. Storchak

15. Xenes heterostructures by C. Grazianetti and A. Molle

16. Integration paths for Xenes by G. Faraone, Md. H. Alam, X. Xu,

Z. Dang, L. Tao, D. Akinwande, and D. Tanneja

Goals

Fill the gap

The number of synthetic Xenes is nowadays tremendously expanding and so is their potential in applications. Some of them may work for electronic devices with benefit on the power consumption; some are suitable for topological matters and more. Overall, a viable technology integration path is still missing, and fulfil this gap is the key enabling step for a Xene to have an impact on applications (nanoelectronics, photonics, energy, etc.) as well as societal challenges (internet of things, smart living, etc.)

Put pieces together

Nowadays, Xenes are a puzzle of different materials. Some Xenes are produced as nanoscale pieces, The XFab objective is reassemble the Xene puzzle in a unitary framework where only the Xenes that can bear a viable application will be selected. Requisites are large-scale synthesis and atomically-resolved identification.

One step closer to applications

Field-effect transistor is the flag-vehicle to disclose the Xene ID. But it is not the only technology enabler. Xenes can be reduced to junctions or other gated structures for energy and photonics applications as well. Main bottlenecks are the stabilization and handling from the pristine form of epitaxial 2D lattices. Xene integration into operational devices will be a key-target.

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