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나노 구조 물리 연구단
나노구조물리 연구단
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Unveiling the Hot Carrier Distribution in Vertical Graphene/h-BN/Au van der Waals Heterostructures for High-Performance Photodetector

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Title
Unveiling the Hot Carrier Distribution in Vertical Graphene/h-BN/Au van der Waals Heterostructures for High-Performance Photodetector
Author(s)
Young Rae Kim; Young Rae Kim; Yong Seon Shin; Won Tae Kang; Ui Yeon Won; Ilmin Lee; Ji Eun Kim; Kunnyun Kim; Young Hee Lee; Woo Jong Yu
Publication Date
2020-03
Journal
ACS APPLIED MATERIALS & INTERFACES, v.12, no.9, pp.10772 - 10780
Publisher
AMER CHEMICAL SOC
Abstract
© 2020 American Chemical Society. Graphene is one of the most promising materials for photodetectors due to its ability to convert photons into hot carriers within approximately 50 fs and generate long-lived thermalized states with lifetimes longer than 1 ps. In this study, we demonstrate a wide range of vertical photodetectors having a graphene/h-BN/Au heterostructure in which an hexagonal boron nitride (h-BN) insulating layer is inserted between an Au electrode and graphene photoabsorber. The photocarriers effectively tunnel through the small hole barrier (1.93 eV) at the Au/h-BN junction while the dark carriers are highly suppressed by a large electron barrier (2.27 eV) at the graphene/h-BN junction. Thus, an extremely low dark current of similar to 10(-13) A is achieved, which is 8 orders of magnitude lower than that of graphene lateral photodetector devices (similar to 10(-5) A). Also, our device displays an asymmetric photoresponse behavior due to photothermionic emission at the graphene/h-BN and Au/h-BN junctions. The asymmetric behavior generates additional thermal carriers (hot carriers) to enable our device to generate photocurrents that can overcome the Schottky barrier. Furthermore, our device shows the highest value of the I-ph/I-dark ratio of similar to 225 at 7 nm thick h-BN insulating layer, which is 3 orders of magnitude larger than that of the previously reported graphene lateral photodetectors without any active materials. In addition, we achieve a fast response speed of 12 mu s of rise time and 5 mu s of fall time, which are about 100 times faster than those of other graphene integrated photodetectors
URI
https://pr.ibs.re.kr/handle/8788114/7146
ISSN
1944-8244
Appears in Collections:
Center for Integrated Nanostructure Physics(나노구조물리 연구단) > Journal Papers (저널논문)
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