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Nature of carrier injection in metal/2D-semiconductor interface and its implications for the limits of contact resistance

Somvanshi, Divya and Kallatt, Sangeeth and Venkatesh, Chenniappan and Nair, Smitha and Gupta, Garima and Anthony, John Kiran and Karmakar, Debjani and Majumdar, Kausik (2017) Nature of carrier injection in metal/2D-semiconductor interface and its implications for the limits of contact resistance. In: PHYSICAL REVIEW B, 96 (20).

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Official URL: http://doi.org/10.1103/PhysRevB.96.205423


Monolayers of transition metal dichalcogenides (TMDCs) exhibit excellent electronic and optical properties. However, the performance of these two-dimensional (2D) devices are often limited by the large resistance offered by the metal contact interface. To date, the carrier injection mechanism from metal to 2D TMDC layers remains unclear, with widely varying reports of Schottky barrier height (SBH) and contact resistance (Rc), particularly in the monolayer limit. In this paper, we use a combination of theory and experiments in Au and Ni contacted monolayer MoS2 device to elucidate the following points: (i) the carriers are injected at the source contact through a cascade of two potential barriers-the barrier heights being determined by the degree of interaction between the metal and the TMDC layer; (ii) the conventional Richardson equation becomes invalid due to the multidimensional nature of the injection barriers, and using Bardeen-Tersoff theory, we derive the appropriate form of the Richardson equation that describes such a composite barrier; (iii) we propose a novel transfer length method (TLM) based SBH extraction methodology, to reliably extract SBH by eliminating any confounding effect of temperature dependent channel resistance variation; (iv) we derive the Landauer limit of the contact resistance achievable in such devices. A comparison of the limits with the experimentally achieved contact resistance reveals plenty of room for technological improvements.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 07 Dec 2017 09:53
Last Modified: 07 Dec 2017 09:53
URI: http://eprints.iisc.ac.in/id/eprint/58388

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