Graphene photodetectors with ultra-broadband and high responsivity at room temperature
The ability to detect light over a broad spectral range is central to several technological applications in imaging, sensing, spectroscopy and communication 1 , 2 . Graphene is a promising candidate material for ultra-broadband photodetectors, as its absorption spectrum covers the entire ultraviolet...
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Published in | Nature nanotechnology Vol. 9; no. 4; pp. 273 - 278 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group UK
01.04.2014
Nature Publishing Group |
Subjects | |
Online Access | Get full text |
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Summary: | The ability to detect light over a broad spectral range is central to several technological applications in imaging, sensing, spectroscopy and communication
1
,
2
. Graphene is a promising candidate material for ultra-broadband photodetectors, as its absorption spectrum covers the entire ultraviolet to far-infrared range
3
,
4
. However, the responsivity of graphene-based photodetectors has so far been limited to tens of mA W
−1
(refs
5
,
6
,
7
,
8
,
9
,
10
) due to the small optical absorption of a monolayer of carbon atoms. Integration of colloidal quantum dots in the light absorption layer can improve the responsivity of graphene photodetectors to ∼1 × 10
7
A W
−1
(ref.
11
), but the spectral range of photodetection is reduced because light absorption occurs in the quantum dots. Here, we report an ultra-broadband photodetector design based on a graphene double-layer heterostructure. The detector is a phototransistor consisting of a pair of stacked graphene monolayers (top layer, gate; bottom layer, channel) separated by a thin tunnel barrier. Under optical illumination, photoexcited hot carriers generated in the top layer tunnel into the bottom layer, leading to a charge build-up on the gate and a strong photogating effect on the channel conductance. The devices demonstrated room-temperature photodetection from the visible to the mid-infrared range, with mid-infrared responsivity higher than 1 A W
−1
, as required by most applications
12
. These results address key challenges for broadband infrared detectors, and are promising for the development of graphene-based hot-carrier optoelectronic applications.
A pair of stacked graphene layers separated by a tunnel barrier show sensitive photodetection capabilities. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 |
ISSN: | 1748-3387 1748-3395 |
DOI: | 10.1038/nnano.2014.31 |