Graphene/nitrogen-functionalized graphene quantum dot hybrid broadband photodetectors with a buffer layer of boron nitride nanosheets.

Hiroyuki Tetsuka,Akihiro Nagoya,Shin-Ichi Tamura

doi:10.1039/c6nr07707b

Hiroyuki Tetsuka, Akihiro Nagoya + Show 1 more

Open Access

https://doi.org/10.1039/c6nr07707b

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Abstract

A high performance hybrid broadband photodetector with graphene/nitrogen-functionalized graphene quantum dots (NGQDs@GFET) is developed using boron nitride nanosheets (BN-NSs) as a buffer layer to facilitate the separation and transport of photoexcited carriers from the NGQD absorber. The NGQDs@GFET photodetector with the buffer layer of BN-NSs exhibits enhanced photoresponsivity and detectivity in the deep ultraviolet region of ca. 2.3 × 106 A W-1 and ca. 5.5 × 1013 Jones without the application of a backgate voltage. The high level of photoresponsivity persists into the near-infrared region (ca. 3.4 × 102 A W-1 and 8.0 × 109 Jones). In addition, application in flexible photodetectors is demonstrated by the construction of a structure on a polyethylene terephthalate (PET) substrate. We further show the feasibility of using our flexible photodetectors towards the practical application of infrared photoreflectors. Together with the potential application of flexible photodetectors and infrared photoreflectors, the proposed hybrid photodetectors have potential for use in future graphene-based optoelectronic devices.

Highlights

Graphene has drawn considerable attention due to its outstanding electrical and optical properties
Insertion of the boron nitride nanosheets (BN-NSs) layer is intended to prevent the recombination of photoexcited carriers at the interface with the graphene/nitrogen-functionalized graphene quantum dots (NGQDs) layer and facilitate the transport of photogenerated electrons from the NGQD layer to graphene, through the vacancy states of BN-NSs formed in the bandgap near the lowest unoccupied molecular orbital (LUMO) levels of the DAN-graphene quantum dots (GQDs)
Graphene acts as the carrier transport channel, while the BN-NSs act as a buffer layer, and the DAN-GQDs are used as photon absorbers

Summary

Introduction

Graphene has drawn considerable attention due to its outstanding electrical and optical properties. Insertion of the BN-NS layer is intended to prevent the recombination of photoexcited carriers at the interface with the graphene/NGQD layer and facilitate the transport of photogenerated electrons from the NGQD layer to graphene, through the vacancy states of BN-NSs formed in the bandgap near the lowest unoccupied molecular orbital (LUMO) levels of the DAN-GQDs. A much faster response time and high photoresponsivity are expected as a result.

Results

Conclusion