Spatially resolved photoconductivity mapping of MoS<sub>2</sub> / WS<sub>2</sub> lateral heterostructures
ORAL
Abstract
The presence of free carriers directly affects the optical properties of transition metal dichalcogenides. For instance, free carriers directly underpin the competition between neutral excitons and carrier-bound trions and they strongly affect radiative and nonradiative decay pathways. However, despite their fundamental importance for TMDs, spatially resolved studies of the carrier distribution and the associated photoresponse remain challenging. Here we use scanning microwave microscopy (SMM, also called microwave impedance microscopy, MIM) to study the spatial carrier distribution in MoS2/WS2 lateral heterostructures under dark conditions as well as under illumination with photon energy-resolved narrowband illumination. We find strong spatial variations in the photoconductive response throughout the flakes studied. We further find significant long-term dynamics in the optically generated free carriers that manifest themselves in persistent charging and discharging and are strongly correlated with observed spatial variations in the steady-state photoconductive response. A comparison with spatially resolved photoluminescence mapping reveals excellent agreement between the local conductivity determined by SMM and the interplay between trion and exciton emission characteristics.
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Presenters
Samuel Berweger
National Institute of Standards and Technology Boulder, CO
Authors
Samuel Berweger
National Institute of Standards and Technology Boulder, CO
Hanyu Zhang
National Renewable Energy Laboratory, National Renewable Energy Laboratory, Golden, CO
Prasana K Sahoo
Indian Institute of Technology, Kharagpur
Benjamin M Kupp
Pennsylvania State University, State College, PA
Jeffrey L Blackburn
National Renewable Energy Laboratory, National Renewable Energy Laboratory, Golden, CO
Elisa M Miller
National Renewable Energy Laboratory, National Renewable Energy Laboratory, Golden, CO
Dmitri Voronine
Univ of South Florida, University of South Florida, Tampa, FL, Department of Physics, University of South Florida, University of South Florida
Thomas M Wallis
National Institute of Standards and Technology Boulder, CO
Pavel Kabos
National Institute of Standards and Technology, National Institute of Standards and Technology Boulder, CO, National Institute of Standards and Technology Boulder
Sanjini U Nanayakkara
National Renewable Energy Laboratory, National Renewable Energy Laboratory, Golden, CO
