Unusually efficient photocurrent extraction in monolayer van der Waals heterostructure by tunnelling through discretized barriers.
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 MoS2to exclude other extrinsic factors. Photoresponse studies reveal that photoresponsivity in one-layer MoS2is surprisingly higher than that in seven-layer MoS2by seven times. Spectral-dependent studies further show that the internal quantum efficiency in one-layer MoS2can 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 MoS2device.
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.|Department of Electronic and Electrical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.|Samsung-SKKU Graphene Center (SSGC), Suwon 16419, Republic of Korea.
Woo Jong
WJ
Yu
Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.|Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.|Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Quoc An
QA
Vu
Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.|Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Hyemin
H
Oh
Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.|Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Hong Gi
HG
Nam
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Hailong
H
Zhou
School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
Soonyoung
S
Cha
School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
Joo-Youn
JY
Kim
Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
Alexandra
A
Carvalho
Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.|Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Munseok
M
Jeong
School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
Hyunyong
H
Choi
Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
A H
AH
Castro Neto
Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, Republic of Korea.|Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.|Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Young Hee
YH
Lee
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.|California Nanosystems Institute, University of California, Los Angeles, California 90095, USA.
Xiangfeng
X
Duan