Direct View of Hot Carrier Dynamics in Graphene

Johannsen, J.; Ulstrup, Søren; Cilento, Federico; Crepaldi, Alberto; Zacchigna, M.; Cacho, Céphise; Turcu, I. C. Edmond; Springate, E.; Fromm, Felix; Raidel, Christian; Seyller, Thomas; Parmigiani, F.; Grioni, M.; Hofmann, Philip

doi:10.1103/physrevlett.111.027403

Cited by 370 publications

(497 citation statements)

References 35 publications

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“…14 The maximum temperature reached after the thermalization (i.e for t > 40 fs) is significantly lower in the n-doped (2000 K) than in the p-doped graphene (3300 K), as seen in Fig. 2(e).…”

Section: (C) This Is In Agreement With Our Previous Study On P-dopedmentioning

confidence: 80%

Tunable Carrier Multiplication and Cooling in Graphene

et al. 2014

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Time-and angle-resolved photoemission measurements on two doped graphene samples displaying different doping levels reveal remarkable differences in the ultrafast dynamics of the hot carriers in the Dirac cone. In the more strongly (n-)doped graphene, we observe larger carrier multiplication factors (> 3) and a significantly faster phonon-mediated cooling of the carriers back to equilibrium compared to in the less (p-)doped graphene. These results suggest that a careful tuning of the doping level allows for an effective manipulation of graphene's dynamical response to a photoexcitation.

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“…14 The maximum temperature reached after the thermalization (i.e for t > 40 fs) is significantly lower in the n-doped (2000 K) than in the p-doped graphene (3300 K), as seen in Fig. 2(e).…”

Section: (C) This Is In Agreement With Our Previous Study On P-dopedmentioning

confidence: 80%

Tunable Carrier Multiplication and Cooling in Graphene

et al. 2014

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“…This, in combination with the small electron heat capacity, compared to the phonon heat capacity, means that the electrons can reach a temperature easily exceeding 1000 K for a photon fluence on the order of a µJ cm −2 [22,26,[29][30][31][32]. This high electron temperature together with the considerable Seebeck coefficient of graphene leads to a substantial PTE photovoltage in graphene devices.…”

Section: The Photo-thermoelectric Effect In Graphenementioning

confidence: 99%

“…This is followed by ultrafast (<50 fs) electron heating, which creates a quasi-equilibrium distribution that can be described by an increased electron temperature. The details of this heating process have been addressed in a number of experimental [22,23,26,27,[29][30][31][32][33] and theoretical [24,25,28,42,43] studies. The system returns to its original (pre-photoexcitation) state through cooling of the hot electrons, which can occur through interaction with graphene lattice optical or acoustic phonons, and substrate phonons [12,17,28,[44][45][46].…”

Section: Time-resolved Photocurrentmentioning

confidence: 99%

“…So a lower cooling rate (longer lifetime of hot electrons) leads to a larger photocurrent. The electron heating and cooling dynamics in bulk graphene have been studied using pump-probe measurements, such as optical pumpprobe [22,31,33,34], femtosecond time-resolved angleresolved photo-electron spectroscopy (ARPES) [30,32], and time-resolved optical pump-terahertz (THz) probe spectroscopy [26,[35][36][37][38][39][40][41]. The photoexcited carrier dynamics have also been studied in graphene-based devices through time-resolved photocurrent scanning microscopy [7,8,17,29].…”

Section: Time-resolved Photocurrentmentioning

confidence: 99%

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Hot-carrier photocurrent effects at graphene–metal interfaces

Tielrooij¹,

Massicotte²,

Piątkowski³

et al. 2015

J. Phys.: Condens. Matter

102

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Photoexcitation of graphene leads to an interesting sequence of phenomena, some of which can be exploited in optoelectronic devices based on graphene. In particular, the efficient and ultrafast generation of an electron distribution with an elevated electron temperature and the concomitant generation of a photo-thermoelectric voltage at symmetry-breaking interfaces is of interest for photosensing and light harvesting. Here, we experimentally study the generated photocurrent at the graphene-metal interface, focusing on the time-resolved photocurrent, the effects of photon energy, Fermi energy and light polarization. We show that a single framework based on photo-thermoelectric photocurrent generation explains all experimental results.

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“…Hot carriers in graphitic materials hold enduring interest in culture, science, and technology [1][2][3][4][5][6][7][8]. In embers radiating blackbody radiation, hot carriers have provided a source of light and heat since the preindustrial age.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Multiphoton Thermionic Photoemission from Graphite

et al. 2017

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Electronic heating of cold crystal lattices in nonlinear multiphoton excitation can transiently alter their physical and chemical properties. In metals where free electron densities are high and the relative fraction of photoexcited hot electrons is low, the effects are small, but in semimetals, where the free electron densities are low and the photoexcited densities can overwhelm them, the intense femtosecond laser excitation can induce profound changes. In semimetal graphite and its derivatives, strong optical absorption, weak screening of the Coulomb potential, and high cohesive energy enable extreme hot electron generation and thermalization to be realized under femtosecond laser excitation. We investigate the nonlinear interactions within a hot electron gas in graphite through multiphoton-induced thermionic emission. Unlike the conventional photoelectric effect, within about 25 fs, the memory of the excitation process, where resonant dipole transitions absorb up to eight quanta of light, is erased to produce statistical Boltzmann electron distributions with temperatures exceeding 5000 K; this ultrafast electronic heating causes thermionic emission to occur from the interlayer band of graphite. The nearly instantaneous thermalization of the photoexcited carriers through Coulomb scattering to extreme electronic temperatures characterized by separate electron and hole chemical potentials can enhance hot electron surface femtochemistry, photovoltaic energy conversion, and incandescence, and drive graphite-to-diamond electronic phase transition.

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Direct View of Hot Carrier Dynamics in Graphene

Cited by 370 publications

References 35 publications

Tunable Carrier Multiplication and Cooling in Graphene

Tunable Carrier Multiplication and Cooling in Graphene

Hot-carrier photocurrent effects at graphene–metal interfaces

Ultrafast Multiphoton Thermionic Photoemission from Graphite

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