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Enhanced Photoresponse in MoTe 2 Photodetectors with Asymmetric Graphene Contacts
Author(s) -
Wei Xia,
Yan Faguang,
Lv Quanshan,
Zhu Wenkai,
Hu Ce,
Patanè Amalia,
Wang Kaiyou
Publication year - 2019
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201900190
Subject(s) - photodetector , materials science , graphene , optoelectronics , photoconductivity , electric field , photovoltaic system , electrode , voltage , nanotechnology , electrical engineering , chemistry , physics , engineering , quantum mechanics
Atomically thin 2D materials are promising candidates for miniaturized high‐performance optoelectronic devices. This study reports on multilayer MoTe 2 photodetectors contacted with asymmetric electrodes based on n‐ and p‐type graphene layers. The asymmetry in the graphene contacts creates a large ( E bi ∼ 100 kV cm −1 ) built‐in electric field across the short ( l = 15 nm) MoTe 2 channel, causing a high and broad (λ = 400–1400 nm) photoresponse even without any externally applied voltage. Spatially resolved photovoltage maps reveal an enhanced photoresponse and larger built‐in electric field in regions of the MoTe 2 layer between the two graphene contacts. Furthermore, a fast (∼10 µs) photoresponse is achieved in both the photovoltaic and photoconductive operation modes of the junction. The findings can be extended to other 2D materials and offer prospects for the implementation of asymmetric graphene contacts in future low‐power optoelectronic applications.