Graphene- WS2 van der Waals Hybrid Heterostructure for Photodetector and Memory Device Applications

Mitra, S and Kakkar, S and Ahmed, T and Ghosh, A (2020) Graphene- WS2 van der Waals Hybrid Heterostructure for Photodetector and Memory Device Applications. In: Physical Review Applied, 14 (6).

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Abstract

The intriguing electronic properties of graphene and the strong light-matter interaction in layered transition-metal dichalcogenide (TMDC) make them a natural partner for hybrid devices, not only for optoelectronic device applications, but also to understand the conversion of light to electricity in this atomic scale prototype of a donor-acceptor complex. Here, we describe graphene-on-WS2 binary heterostructure FET device, displaying gate-tunable persistent photoconductivity. Our time-dependent photovoltage relaxation experiments suggest that the charge-transfer time scale in this heterostructure is dependent on the input optical power, contrary to what is observed for the bare TMDC and is orders of magnitude slower than that observed for various other vdW hybrids. The optoelectronic responsivity of this device at low optical power is found to be as high as 1010V/W, and thus shows the potential to be one of the most sensitive visible range photodetectors, while the gate tunability of the persistent photoconductivity can be utilized in the memory device applications. We identify that the photoresponse is the outcome of a photogating mechanism, due to the exciton dissociation under optical excitation, followed by the trapping of holes in WS2 and subsequent electron transfer to graphene. © 2020 American Physical Society.

Item Type:	Journal Article
Publication:	Physical Review Applied
Publisher:	American Physical Society
Additional Information:	Copyright to this article belongs to American Physical Society
Keywords:	Charge transfer; Electron transport properties; Electronic properties; Graphene; Photoconductivity; Photodetectors; Photons; Transition metals; Tungsten compounds; Van der Waals forces, Device application; Donor-acceptor complex; Electronic properties of graphene; Exciton dissociation; Light-matter interactions; Orders of magnitude; Persistent Photoconductivity; Transition metal dichalcogenides, Graphene devices
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	15 Jan 2021 05:23
Last Modified:	15 Jan 2021 05:23
URI:	http://eprints.iisc.ac.in/id/eprint/67612

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