Open AccessSub‐bandgap activated charges transfer in a graphene‐MoS 2 ‐graphene heterostructure
Author(s) -
Kumar Sunil,
Singh Arvind,
Nivedan Anand,
Kumar Sandeep,
Yun Seok Joon,
Lee Young Hee,
Tondusson Marc,
Degert Jérôme,
Oberle Jean,
Freysz Eric
Publication year - 2021
Publication title -
nano select
Language(s) - English
Resource type - Journals
ISSN - 2688-4011
DOI - 10.1002/nano.202000159
Subject(s) - monolayer , graphene , materials science , photodetection , optoelectronics , heterojunction , photoexcitation , molybdenum disulfide , band gap , phosphorene , direct and indirect band gaps , charge carrier , terahertz radiation , nanotechnology , photodetector , excited state , physics , nuclear physics , metallurgy
Monolayers of transition metal dichalcogenides are semiconducting materials which offer many prospects in optoelectronics. A monolayer of molybdenum disulfide (MoS 2 ) has a direct bandgap of 1.88 eV. Hence, when excited with optical photon energies below its bandgap, no photocarriers are generated and a monolayer of MoS 2 is not of much use in either photovoltaics or photodetection. Here, we demonstrate that large size MoS 2 monolayer sandwiched between two graphene layers makes this heterostructure optically active well below the band gap of MoS 2 . An ultrafast optical pump‐THz probe experiment reveals in real‐time, transfer of carriers between graphene and MoS 2 monolayer upon photoexcitation with photon energies down to 0.5 eV. It also helps to unravel an unprecedented enhancement in the broadband transient THz response of this tri‐layer material system. We propose possible mechanism which can account for this phenomenon. Such specially designed heterostructures, which can be easily built around different transition metal dichalcogenide monolayers, will considerably broaden the scope for modern optoelectronic applications at THz bandwidth.