Microwave Photodetection in an Ultraclean Suspended Bilayer Graphene p-n Junction.
Nano Lett
; 16(11): 6988-6993, 2016 11 09.
Article
em En
| MEDLINE
| ID: mdl-27704863
ABSTRACT
We explore the potential of bilayer graphene as a cryogenic microwave photodetector by studying the microwave absorption in fully suspended clean bilayer graphene p-n junctions in the frequency range of 1-5 GHz at a temperature of 8 K. We observe a distinct photocurrent signal if the device is gated into the p-n regime, while there is almost no signal for unipolar doping in either the n-n or p-p regimes. Most surprisingly, the photocurrent strongly peaks when one side of the junction is gated to the Dirac point (charge-neutrality point CNP), while the other remains in a highly doped state. This is different to previous results where optical radiation was used. We propose a new mechanism based on the phototermal effect explaining the large signal. It requires contact doping and a distinctly different transport mechanism on both sides one side of graphene is ballistic and the other diffusive. By engineering partially diffusive and partially ballistic devices, the photocurrent can drastically be enhanced.
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MEDLINE
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En
Revista:
Nano Lett
Ano de publicação:
2016
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Article
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