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Article: Ultrafast hot-carrier-dominated photocurrent in graphene

TitleUltrafast hot-carrier-dominated photocurrent in graphene
Authors
Issue Date2012
PublisherNature Publishing Group.
Citation
Nature Nanotechnology, 2012, v. 7 n. 2, p. 114-118 How to Cite?
AbstractThe combination of its high electron mobility, broadband absorption and ultrafast luminescence make graphene attractive for optoelectronic and photonic applications, including transparent electrodes, mode-locked lasers and high-speed optical modulators. Photo-excited carriers that have not cooled to the temperature of the graphene lattice are known as hot carriers, and may limit device speed and energy efficiency. However, their roles in charge and energy transport are not fully understood. Here, we use time-resolved scanning photocurrent microscopy to demonstrate that hot carriers, rather than phonons, dominate energy transport across a tunable graphene p-n junction excited by ultrafast laser pulses. The photocurrent response time varies from 1.5 ps at room temperature to 4 ps at 20 K, implying a fundamental bandwidth of approximately 500 GHz (refs 12, 13, 21). Gate-dependent pump-probe measurements demonstrate that both thermoelectric and built-in electric field effects contribute to the photocurrent, with the contribution from each depending on the junction configuration. The photocurrent produced by a single pulsed laser also displays multiple polarity reversals as a function of carrier density, which is a possible signature of impact ionization.
Persistent Identifierhttp://hdl.handle.net/10722/145924
ISSN
2015 Impact Factor: 35.267
2015 SCImago Journal Rankings: 19.832
ISI Accession Number ID
Funding AgencyGrant Number
DARPA YFA
US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and EngineeringDE-SC0002197
IBM4910031201
NSFDGE-0718124
Funding Information:

The authors thank Z. Zhong for helpful suggestions on device fabrication and T. Norris for useful discussions. X. Xu acknowledges support from DARPA YFA. The research was supported in part by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering (DE-SC0002197). D. Sun acknowledges partial support from IBM (4910031201). A. Jones was supported by the NSF Graduate Research Fellowship (DGE-0718124). Device fabrication was performed at the University of Washington Nanotechnology User Facility funded by the NSF. X. Xu thanks B. Heckel, B. Blinov and L. Sorensen for help with the laboratory set-up.

References

 

DC FieldValueLanguage
dc.contributor.authorSun, Den_HK
dc.contributor.authorAivazian, Gen_HK
dc.contributor.authorJones, AMen_HK
dc.contributor.authorRoss, JSen_HK
dc.contributor.authorYao, Wen_HK
dc.contributor.authorCobden, Den_HK
dc.contributor.authorXu, Xen_HK
dc.date.accessioned2012-03-27T09:02:09Z-
dc.date.available2012-03-27T09:02:09Z-
dc.date.issued2012en_HK
dc.identifier.citationNature Nanotechnology, 2012, v. 7 n. 2, p. 114-118en_HK
dc.identifier.issn1748-3387en_HK
dc.identifier.urihttp://hdl.handle.net/10722/145924-
dc.description.abstractThe combination of its high electron mobility, broadband absorption and ultrafast luminescence make graphene attractive for optoelectronic and photonic applications, including transparent electrodes, mode-locked lasers and high-speed optical modulators. Photo-excited carriers that have not cooled to the temperature of the graphene lattice are known as hot carriers, and may limit device speed and energy efficiency. However, their roles in charge and energy transport are not fully understood. Here, we use time-resolved scanning photocurrent microscopy to demonstrate that hot carriers, rather than phonons, dominate energy transport across a tunable graphene p-n junction excited by ultrafast laser pulses. The photocurrent response time varies from 1.5 ps at room temperature to 4 ps at 20 K, implying a fundamental bandwidth of approximately 500 GHz (refs 12, 13, 21). Gate-dependent pump-probe measurements demonstrate that both thermoelectric and built-in electric field effects contribute to the photocurrent, with the contribution from each depending on the junction configuration. The photocurrent produced by a single pulsed laser also displays multiple polarity reversals as a function of carrier density, which is a possible signature of impact ionization.en_HK
dc.languageengen_US
dc.publisherNature Publishing Group.en_US
dc.relation.ispartofNature Nanotechnologyen_HK
dc.subject.meshElectrodes-
dc.subject.meshElectrons-
dc.subject.meshGraphite - chemistry-
dc.subject.meshNanostructures - chemistry-
dc.subject.meshPhotons-
dc.titleUltrafast hot-carrier-dominated photocurrent in grapheneen_HK
dc.typeArticleen_HK
dc.identifier.emailXu, X: xuxd@uw.eduen_HK
dc.identifier.emailYao, W: wangyao@hkucc.hku.hk-
dc.identifier.authorityYao, W=rp00827en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1038/nnano.2011.243en_HK
dc.identifier.pmid22245859-
dc.identifier.scopuseid_2-s2.0-84862777523en_HK
dc.identifier.hkuros199048en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-84862777523&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume7en_HK
dc.identifier.issue2en_HK
dc.identifier.spage114en_HK
dc.identifier.epage118en_HK
dc.identifier.eissn1748-3395-
dc.identifier.isiWOS:000300398900013-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridXu, X=36672409300en_HK
dc.identifier.scopusauthoridCobden, D=6603922015en_HK
dc.identifier.scopusauthoridYao, W=35141935300en_HK
dc.identifier.scopusauthoridRoss, JS=55261611900en_HK
dc.identifier.scopusauthoridJones, AM=54892641700en_HK
dc.identifier.scopusauthoridAivazian, G=35725074000en_HK
dc.identifier.scopusauthoridSun, D=14830883600en_HK
dc.identifier.citeulike11500695-

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