Substrate effects on the speed limiting factor of WSe2 photodetectors

We investigate the time-resolved photoelectric response of WSe2 crystals on glass and flexible polyimide substrates to determine the effect of a changed dielectric environment on the speed of the photodetectors. We show that varying the substrate material can alter the speed-limiting mechanism: whil...

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Bibliographic Details
Published inPhysical chemistry chemical physics : PCCP Vol. 24; no. 41; pp. 25383 - 25390
Main Authors Schedel, Christine, Strauß, Fabian, Kohlschreiber, Pia, Geladari, Olympia, Meixner, Alfred J, Scheele, Marcus
Format Journal Article
LanguageEnglish
Published Cambridge Royal Society of Chemistry 27.10.2022
Subjects
Depletion
Diffusion layers
Diffusion rate
Electric fields
Glass substrates
Limiting factors
Photoelectricity
Photometers
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Summary:We investigate the time-resolved photoelectric response of WSe2 crystals on glass and flexible polyimide substrates to determine the effect of a changed dielectric environment on the speed of the photodetectors. We show that varying the substrate material can alter the speed-limiting mechanism: while the detectors on polyimide are RC limited, those on glass are limited by slower excitonic diffusion processes. We attribute this to a shortening of the depletion layer at the metal electrode/WSe2 interface caused by the higher dielectric screening of glass compared to polyimide. The photodetectors on glass show a tunable bandwidth, which can be increased to 2.6 MHz with increasing the electric field.
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ISSN:1463-9076
1463-9084
DOI:10.1039/d2cp03364j