The Physics behind the Modulation of Thermionic Current in Photodetectors Based on Graphene Embedded between Amorphous and Crystalline Silicon

In this work, we investigate a vertically illuminated near-infrared photodetector based on a graphene layer physically embedded between a crystalline and a hydrogenated silicon layer. Under near-infrared illumination, our devices show an unforeseen increase in the thermionic current. This effect has...

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Bibliographic Details
Published in:Nanomaterials (Basel, Switzerland) Switzerland), 2023-02, Vol.13 (5), p.872
Main Authors: Crisci, Teresa, Maccagnani, Piera, Moretti, Luigi, Summonte, Caterina, Gioffrè, Mariano, Rizzoli, Rita, Casalino, Maurizio
Format: Article
Language:English
Subjects:
Amorphous silicon
Analysis
Current carriers
encapsulation
Graphene
Graphite
I.R. radiation
Illumination
Infrared detectors
Interfaces
near infrared
photodetector
Photometers
Photovoltaic cells
Quantum dots
Silicon
silicon photonics
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Summary:In this work, we investigate a vertically illuminated near-infrared photodetector based on a graphene layer physically embedded between a crystalline and a hydrogenated silicon layer. Under near-infrared illumination, our devices show an unforeseen increase in the thermionic current. This effect has been ascribed to the lowering of the graphene/crystalline silicon Schottky barrier as the result of an upward shift in the graphene Fermi level induced by the charge carriers released from traps localized at the graphene/amorphous silicon interface under illumination. A complex model reproducing the experimental observations has been presented and discussed. Responsivity of our devices exhibits a maximum value of 27 mA/W at 1543 nm under an optical power of 8.7 μW, which could be further improved at lower optical power. Our findings offer new insights, highlighting at the same time a new detection mechanism which could be exploited for developing near-infrared silicon photodetectors suitable for power monitoring applications.
ISSN:2079-4991
2079-4991
DOI:10.3390/nano13050872