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Electrical contacts to two-dimensional semiconductors

Abstract

The performance of electronic and optoelectronic devices based on two-dimensional layered crystals, including graphene, semiconductors of the transition metal dichalcogenide family such as molybdenum disulphide (MoS2) and tungsten diselenide (WSe2), as well as other emerging two-dimensional semiconductors such as atomically thin black phosphorus, is significantly affected by the electrical contacts that connect these materials with external circuitry. Here, we present a comprehensive treatment of the physics of such interfaces at the contact region and discuss recent progress towards realizing optimal contacts for two-dimensional materials. We also discuss the requirements that must be fulfilled to realize efficient spin injection in transition metal dichalcogenides.

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Figure 1: Interface geometries of metal–2D contacts.
Figure 2: Different types of metal–SC junction and their respective band diagrams.
Figure 3: Various 'seamless' contact schemes.
Figure 4: Charge-injection mechanisms and extraction of the SBH.
Figure 5
Figure 6: Current crowding at the contact edge region.
Figure 7: Contact resistance for top-contacted 2D SCs.
Figure 8: Spin injection and contact resistance.

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Acknowledgements

This work was performed in frames of the Marie Curie ITN network MoWSeS (grant no. 317451). We acknowledge funding by the European Commission under the Graphene Flagship (grant agreement no. 604391), the US National Science Foundation under Grant CCF-1162633 and the US Air Force Office of Scientific Research under Grant FA9550-14-1-0268 (R18641).

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Allain, A., Kang, J., Banerjee, K. et al. Electrical contacts to two-dimensional semiconductors. Nature Mater 14, 1195–1205 (2015). https://doi.org/10.1038/nmat4452

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