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Unusually efficient photocurrent extraction in monolayer van der Waals heterostructure by tunnelling through discretized barriers

TitleUnusually efficient photocurrent extraction in monolayer van der Waals heterostructure by tunnelling through discretized barriers
Publication TypeJournal Article
Year of Publication2016
AuthorsYu, Woo Jong, Vu Quoc An, Oh Hyemin, Nam Hong Gi, Zhou Hailong, Cha Soonyoung, Kim Joo-Youn, Carvalho Alexandra, Jeong Munseok, Choi Hyunyong, Neto A. H. Castro, Lee Young Hee, and Duan Xiangfeng
JournalNat. Commun.
Volume7
Pagination13278
Date Published11/2016
ISSN2041-1723
Keywordscrystals, electronics, films, graphene heterostructures, insulator-transition, layered materials, MoS2, transistors, transition-metal dichalcogenides, vertical heterostructures
Abstract

Two-dimensional layered transition-metal dichalcogenides have attracted considerable interest for their unique layer-number-dependent properties. In particular, vertical integration of these two-dimensional crystals to form van der Waals heterostructures can open up a new dimension for the design of functional electronic and optoelectronic devices. Here we report the layer-number-dependent photocurrent generation in graphene/MoS2/graphene heterostructures by creating a device with two distinct regions containing one-layer and seven-layer MoS2 to exclude other extrinsic factors. Photoresponse studies reveal that photoresponsivity in one-layer MoS2 is surprisingly higher than that in seven-layer MoS2 by seven times. Spectral-dependent studies further show that the internal quantum efficiency in one-layer MoS2 can reach a maximum of 65%, far higher than the 7% in seven-layer MoS2. Our theoretical modelling shows that asymmetric potential barriers in the top and bottom interfaces of the graphene/one-layer MoS2/graphene heterojunction enable asymmetric carrier tunnelling, to generate usually high photoresponsivity in one-layer MoS2 device.

DOI10.1038/ncomms13278

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