AVS 66th International Symposium & Exhibition
    2D Materials Monday Sessions
       Session 2D+AP+EM+MI+MN+NS+PS+TF-MoA

Paper 2D+AP+EM+MI+MN+NS+PS+TF-MoA5
van der Waals Heterojunction Photothermoelectric Effect in MoS2/Graphene Monolayers

Monday, October 21, 2019, 3:00 pm, Room A226

Session: Nanostructures including Heterostructures and Patterning of 2D Materials
Presenter: Yunqiu Kelly Luo, The Ohio State University
Authors: YK. Luo, The Ohio State University
T. Zhou, University at Buffalo, State University of New York
M. Newburger, The Ohio State Univesity
R. Bailey-Crandell, The Ohio State University
I. Lyalin, The Ohio State University
M. Neupane, U.S. Army Research Laboratory
A. Matos-Abiague, Wayne State University
I. Zutic, University at Buffalo, State University of New York
R. Kawakami, The Ohio State University
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Two-dimensional (2D) van der Waals (vdW) heterostructures provide a vast playground for exploring new phenomena due to its unique ability to tailor and combine dissimilar materials with atomic precision. In particular, the combination of graphene and transition metal dichalcogenides (TMDC) garners immense interest due to their novel optoelectronic, valleytronic and spintronic properties. Here, we report the observation of a highly tunable vdW heterojunction photothermoelectric effect (HPTE) in dual-gated MoS2/graphene heterostructures, identified by a signature six-fold photocurrent pattern as a function of heterojunction bias and carrier density. In stark contrast to photovoltaic and photothermionic effects, we discover a new mechanism arising from photoexcitation of hot electrons in graphene and subsequent thermoelectric transport across the vdW junction. While analogous to lateral photothermoelectric effects at quasi-1D junctions in single layers, the vertical geometry of HPTE offers area scaling of 2D active regions and establishes, for the first time, the photothermoelectric response in vdW heterostructures. Operating at both low (18 K) and room temperatures, the discovery of HPTE creates new possibilities for electrically-tunable broadband photodetectors and atomically-thin spin caloritronic devices.