Hot Carrier–Assisted Intrinsic Photoresponse in Graphene

Gabor, Nathaniel; Song, Justin C. W.; Ma, Qiong; Nair, Nityan; Taychatanapat, Thiti; Watanabe, Kenji; Taniguchi, Takashi; Levitov, L. S.; Jarillo‐Herrero, Pablo

doi:10.1126/science.1211384

Cited by 951 publications

(1,192 citation statements)

References 47 publications

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“…The interference between surface plasmon polaritons and the incident wave introduces new functionalities, such as light flux attraction or repulsion from the contact edges, enabling the tailored design of the photodetector's spectral response. This architecture can also be used for surface plasmon bio-sensing with direct-electricreadout, eliminating the need of complicated optics.Graphene-based photodetectors (PDs) [1,2] have been reported with ultra-fast operating speeds (up to 262GHz from the measured intrinsic response time of graphene carriers [3]) and broadband operation from the visible and infrared [3][4][5][6][7][8][9][10][11][12][13][14][15][16] up to the THz [17][18][19]. The simplest graphene-based photodetection scheme relies on the metal-graphene-metal (MGM) architecture [5,7,8,11,[20][21][22], where the photoresponse is due to a combination of photo-thermoelectric and photovoltaic effects [5,7,8,11,[20][21][22].…”

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confidence: 99%

Surface Plasmon Polariton Graphene Photodetectors

et al. 2015

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The combination of plasmonic nanoparticles and graphene enhances the responsivity and spectral selectivity of graphene-based photodetectors. However, the small area of the metal-graphene junction, where the induced electron-hole pairs separate, limits the photoactive region to sub-micron length scales. Here, we couple graphene with a plasmonic grating and exploit the resulting surface plasmon polaritons to deliver the collected photons to the junction region of a metal-graphenemetal photodetector. This results into a 400% enhancement of responsivity and a 1000% increase in photoactive length, combined with tunable spectral selectivity. The interference between surface plasmon polaritons and the incident wave introduces new functionalities, such as light flux attraction or repulsion from the contact edges, enabling the tailored design of the photodetector's spectral response. This architecture can also be used for surface plasmon bio-sensing with direct-electricreadout, eliminating the need of complicated optics.Graphene-based photodetectors (PDs) [1,2] have been reported with ultra-fast operating speeds (up to 262GHz from the measured intrinsic response time of graphene carriers [3]) and broadband operation from the visible and infrared [3][4][5][6][7][8][9][10][11][12][13][14][15][16] up to the THz [17][18][19]. The simplest graphene-based photodetection scheme relies on the metal-graphene-metal (MGM) architecture [5,7,8,11,[20][21][22], where the photoresponse is due to a combination of photo-thermoelectric and photovoltaic effects [5,7,8,11,[20][21][22]. For both mechanisms, the presence of a junction is required to spatially separate excited electronhole (e-h) pairs [5,7,8,11,[20][21][22]. At the metal-graphene junction, a work-function difference causes charge transfer and a shift of the graphene Fermi level underneath the contact [4,5,7,23], compared to that of graphene away from the contact [4,5,7,23], resulting into a build-up of an internal electric field (photovoltaic mechanism) [5,7,24,25] and into a difference of Seebeck coefficients (photo-thermoelectric mechanism) [11,21,26]. An alternative way to create a junction is to use a set of gate electrodes to electrostatically dope graphene [8,11].

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Surface Plasmon Polariton Graphene Photodetectors

et al. 2015

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“…To this end, we can take advantage of the excellent optical and electronic properties of graphene 9 , which include good photodetection capabilities 8,[10][11][12][13][14][15] , efficient energy absorption 3 and strong light-matter interactions at the nanoscale 16,17 . In particular, it has been reported recently that, because of graphene's specific properties, the near-field interaction between light emitters and graphene is greatly enhanced as compared to that of conventional metals [2][3][4][5][6] .…”

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Ultrafast electronic readout of diamond nitrogen–vacancy centres coupled to graphene

et al. 2014

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Non-radiative transfer processes are often regarded as loss channels for an optical emitter 1 because they are inherently difficult to access experimentally. Recently, it has been shown that emitters, such as fluorophores and nitrogen-vacancy centres in diamond, can exhibit a strong non-radiative energy transfer to graphene [2][3][4][5][6] . So far, the energy of the transferred electronic excitations has been considered to be lost within the electron bath of the graphene. Here we demonstrate that the transferred excitations can be read out by detecting corresponding currents with a picosecond time resolution 7,8 . We detect electronically the spin of nitrogen-vacancy centres in diamond and control the non-radiative transfer to graphene by electron spin resonance. Our results open the avenue for incorporating nitrogen-vacancy centres into ultrafast electronic circuits and for harvesting non-radiative transfer processes electronically.With the advancement of nanoscale photonics research it has become increasingly desirable to combine optical systems with electric circuits to create optoelectronic devices that can be miniaturized and integrated into chips. To this end, we can take advantage of the excellent optical and electronic properties of graphene 9 , which include good photodetection capabilities 8,10-15 , efficient energy absorption 3 and strong light-matter interactions at the nanoscale 16,17 . In particular, it has been reported recently that, because of graphene's specific properties, the near-field interaction between light emitters and graphene is greatly enhanced as compared to that of conventional metals 2-6 . This interaction manifests itself, for example, in a 100-fold enhancement of the excited-state decay rate of emitters placed 5 nm away from graphene as compared to the spontaneous emission of the emitter. The physical mechanism behind the interaction is the creation of an electron-hole pair in graphene through non-radiative energy transfer (NRET) from the emitter dipole 18 . The NRET process to graphene has been demonstrated to have an efficiency of nearly 100% when the emitter is less than 10 nm away from the graphene sheet 3 , which makes graphene an ideal material to detect electronically the optical properties of nearby emitters 6 . NRET has been studied extensively for fundamental as well as for biosensing applications. However, a fast energy transfer has not yet been observed because of quenching of the optical signal for short graphene-emitter distances. In contrast, an electronic readout of the NRET enables studies on fast energy processes. Moreover, if the transferred energy can be collected, as we show in this work, new ways for energy harvesting and biosensing can be implemented.We take advantage of the highly efficient NRET process to read out electronically, for the first time, the optical excitation of nitrogen-vacancy (NV) centres in diamond nanocrystals. To this end, we used graphene for the extraction of the excited-state energy of NV centres and converted it into a measurable ...

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“…We can isolate a dephasing rate of ~ (5 fs) -1 from excitonphonon coupling and a decay rate of ~ (10 fs) -1 from exciton-electron coupling at doping level of ~0.45 e/nm. Such knowledge on ultrafast relaxation will be important for optoelectronic applications employing hot electrons in carbon nanotube and graphene 29,30 .…”

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High-throughput optical imaging and spectroscopy of individual carbon nanotubes in devices

et al. 2013

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* These two authors contribute equally to this work 2 Two paramount challenges in carbon nanotube research are achieving chiralitycontrolled synthesis and understanding chirality-dependent device physics 1-7 . Highthroughput and in-situ chirality and electronic structural characterization of individual carbon nanotubes is crucial for addressing these challenges. Optical imaging and spectroscopy has unparalleled throughput and specificity 8-14 , but its realization for single nanotubes on substrates or in devices has long been an outstanding challenge.Here we demonstrate video-rate imaging and in-situ spectroscopy of individual carbon nanotubes on various substrates and in functional devices using a novel high-contrast polarization-based optical microscopy. Our technique enables the complete chirality profiling of hundreds of as-grown carbon nanotubes. In addition, we in-situ monitor nanotube electronic structure in active field-effect devices, and observe that high-order nanotube optical resonances are dramatically broadened by electrostatic doping. This unexpected behaviour points to strong interband electron-electron scattering processes that can dominate ultrafast dynamics of excited states in carbon nanotubes.3 Single-walled carbon nanotubes (SWNTs) comprise a large family of tubular carbon structures characterized by different chiral indices (n, m), each having distinct electronic structure and physical properties 1 . They are promising materials for next generation nanoelectronic and nano-photonic devices, including field-effect transistors, light emitters and photocurrent/photovoltaics device [1][2][3][4][5][6][7] . Currently nanotube research faces two outstanding challenges: (1) achieving chirality-controlled nanotube growth and (2) understanding chirality-dependent nanotube device physics. Addressing these challenges requires, respectively, high-throughput determination of nanotube chirality distribution on growth substrates and in-situ characterization of nanotube electronic structure in operating devices.Direct optical imaging and spectroscopy is well suited for these goals [8][9][10][11][12][13][14] , but its realization for single nanotubes on substrates or in devices has been an outstanding challenge due to small nanotube signal and unavoidable environment background. Here we demonstrate for the first time high-throughput real-time optical imaging and broadband spectroscopy of individual nanotubes in devices using a polarization-based microscopy combined with supercontinuum laser illumination. Our technique is generally applicable to semiconducting and metallic nanotubes in various configurations, such as on (transparent or opaque) substrates, between contact electrodes, and under top gates. This is in contrast to strong constraints limiting other prevailing single-tube spectroscopy techniques: single-tube fluorescence spectroscopy only works for isolated semiconducting nanotubes 8 ; Rayleigh scattering requires nanotubes suspended or oil-immersed on transparent substrate 9-12 ; and resonant Ra...

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Hot Carrier–Assisted Intrinsic Photoresponse in Graphene

Cited by 951 publications

References 47 publications

Surface Plasmon Polariton Graphene Photodetectors

Surface Plasmon Polariton Graphene Photodetectors

Ultrafast electronic readout of diamond nitrogen–vacancy centres coupled to graphene

High-throughput optical imaging and spectroscopy of individual carbon nanotubes in devices

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