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Workshops

Two-dimensional inorganic materials (2DIM): property simulations from band structure to devices

January 20, 2014 to January 23, 2014
Location : CECAM-HQ-EPFL, Lausanne, Switzerland
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Unusual conduction at semiconductor surfaces and in non-planar few-layer quasi-2D systems

David Tomanek
Michigan State University, USA

Abstract

Current interest in 2D semiconductors has focused on monolayer (graphene and BN) and few-layer (transition metal chalcogendides such as MoS2) structures. By means of topological protection, 2D conduction may also occur at specific carbon foam surfaces that are completely saturated with hydrogen. Close inspection reveals that the unusual conduction state is related to p|| orbitals in the surface plane of the foam and unrelated to dangling bonds [1]. Topological defects, such as non-hexagonal rings in the honeycomb lattice of graphene[2] and BN, cause ripples in otherwise planar monolayers. Deviation of planarity is of much less consequence for in-layer transport[2-4] than for the inter-layer interaction in few-layer quasi-2D systems. Whereas randomly arranged defects generally reduce the inter-layer coupling, periodic arrangement of ripples and ridges may improve the inter-layer coupling, thereby modifying the electronic structure of few-layer systems. This becomes especially important in systems with natural rather than artificially induced structural rippling.

This study has been performed in collaboration with Zhen Zhu and was supported by the National Science Foundation Cooperative Agreement No. EEC-0832785, titled "NSEC: Center for High-rate Nanomanufacturing."



References

[1] Zhen Zhu, Zacharias G. Fthenakis, Jie Guan, and David Tománek, Phys. Rev. Lett. 112 (2014).
[2] Zacharias G. Fthenakis, Zhen Zhu, and David Tománek (submitted for publication).
[3] Ceren Tayran, Zhen Zhu, Matteo Baldoni, Daniele Selli, Gotthard Seifert, and David Tománek, Phys. Rev. Lett. 110, 176805 (2013).
[4] Daniele Selli, Igor Baburin, Stefano Leoni, Zhen Zhu, David Tománek and Gotthard Seifert, J. Phys.: Cond. Mat. 25, 435302 (2013).