Unipolar optical doping and extended photocarrier lifetime in graphene by band-alignment engineering

Graphene is an attractive material for optoelectronic applications due to its superior charge transport properties and strong and broadband light-matter interaction. In photodetector or photovoltaic devices with graphene as the active material, light absorption generates electron-hole pairs in graph...

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Bibliographic Details
Published in:Nano futures 2018-09, Vol.2 (3), p.35003
Main Authors: Lane, Samuel D, Zhao, Hui
Format: Article
Language:English
Subjects:
graphene
two-dimensional material
ultrafast dynamics
van der Waals heterostructure
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Summary:Graphene is an attractive material for optoelectronic applications due to its superior charge transport properties and strong and broadband light-matter interaction. In photodetector or photovoltaic devices with graphene as the active material, light absorption generates electron-hole pairs in graphene, which give rise to photoconductivity or photovoltaics. However, the lifetime of photocarriers in graphene is only a few picoseconds, which has been a major obstacle for high-performance graphene-based devices. Here we show that by interfacing graphene with two other semiconducting monolayers, unipolar optical doping of graphene can be achieved, which increases its photocarrier lifetime by about two orders of magnitude. In this scheme, by band-alignment engineering, photoexcited electrons and holes are separated in different layers, which suppresses their recombination. Since the efficiency of photodetectors and photovoltaic devices depends strongly on photocarrier lifetime, these new van der Waals materials can significantly improve the performance of graphene-based optoelectronic devices.
ISSN:2399-1984
2399-1984
DOI:10.1088/2399-1984/aace6c