Ultrafast Carrier Dynamics in Graphite

Breusing, Markus; Ropers, Claus; Elsaesser, Thomas

doi:10.1103/physrevlett.102.086809

Cited by 428 publications

(484 citation statements)

References 22 publications

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“…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%

“…In the photo-thermoelectric effect, the temperature difference is created by photoexcitation. Absorbed photons in graphene lead to ultrafast [22,23] and efficient [24][25][26][27] carrier heating. The electron distribution after photoexcitation is characterized by an elevated 'hot' electron temperature T el,hot , compared to the electron temperature without photoexcitation T el,0 (see figure 1(a)).…”

Section: The Photo-thermoelectric Effect In Graphenementioning

confidence: 99%

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Hot-carrier photocurrent effects at graphene–metal interfaces

Tielrooij¹,

Massicotte²,

Piątkowski³

et al. 2015

J. Phys.: Condens. Matter

100

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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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Section: Time-resolved Photocurrentmentioning

confidence: 99%

Section: The Photo-thermoelectric Effect In Graphenementioning

confidence: 99%

Hot-carrier photocurrent effects at graphene–metal interfaces

Tielrooij¹,

Massicotte²,

Piątkowski³

et al. 2015

J. Phys.: Condens. Matter

100

View full text Add to dashboard Cite

show abstract

“…As a semimetal, under linear optical excitation, graphene is nonemissive, but under nonlinear optical or electrical stimulation, it can emit both intense incandescence characterized by blackbody radiation temperatures in excess of 3000 K and broadband coherent radiation [14][15][16][17]. Moreover, strong modulation of the carrier density through ultrafast optical excitation and the ensuing hot carrier multiplication drives the electron and hole distributions to different chemical potentials, enabling applications in energy harvesting, ultrafast electronics, and coherent optics [1,3,[16][17][18][19][20]. These novel properties derive from graphene's Dirac fermion band structure, weak screening, and strong, moleculelike electron correlation [21][22][23][24][25][26][27][28][29][30][31], which distinguish it from conventional metals and semiconductors [22,32,33].…”

Section: Introductionmentioning

confidence: 99%

“…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%

“…Hot electron dynamics in graphene and graphite have been investigated by optical, THz, photoemission, and theoretical methods [1][2][3][4][5][6][7][8][9]23,34,[39][40][41][42][43][44][45][46]. Xu et al [39] first applied ultrafast time-resolved two-photon photoemission (TR-2PP) spectroscopy to excite a hot electron population and monitor its energy-dependent decay in graphite.…”

Section: Introductionmentioning

confidence: 99%

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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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Ultrasensitive Terahertz Nano‐Probing for Semiconductors Using Nanogap Structures

Bahk

Seo

2021

Digital Encyclopedia of Applied Physics

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There has been a growing interest in exploring novel opto‐electrical behaviors and response of carriers under nonequilibrium conditions in semiconductor nanoscale materials for applications of photocurrent and operation of photodetectors. Terahertz waves have shown substantial promise for these applications, with the merit of direct observation of transient carrier dynamics and conductivity changes in semiconductor materials. Especially, to investigate surface carrier dynamics of such nanoscale semiconductor materials under photoexcitation, one can use nanosized materials such as nanofilms, nanowires, and nanoparticles, which have a very large surface‐to‐volume ratio. In this article, we introduce ultrafast phenomena in semiconductors investigated by terahertz probes. In particular, recent studies on how to observe carrier dynamics in a semiconductor with a spatial resolution of nanoscale levels below the diffraction limit of terahertz wave, using well‐tailored metallic nanogap structures are mainly introduced. Metallic nanostructures having the ability to confine electromagnetic waves in a volume much smaller than wavelength play an important role in many application areas such as subwavelength waveguides, metamaterials, biochemical sensing, and photovoltaic technology. Strong local electromagnetic field confinement and enhancement accompanied by metallic nanostructures including nanogaps and nanotips have been widely used to manipulate interaction between electromagnetic waves and target materials. In addition to their diverse applications, their fundamental importance has received a great deal of attention in nano‐optics and nano‐photonics. The tunability of resonances by the geometrical effect of metal nanostructures can be exploited to increase the interaction efficiency between the nanostructures and electromagnetic waves at specific wavelength regions of interest.

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Ultrafast Carrier Dynamics in Graphite

Cited by 428 publications

References 22 publications

Hot-carrier photocurrent effects at graphene–metal interfaces

Hot-carrier photocurrent effects at graphene–metal interfaces

Ultrafast Multiphoton Thermionic Photoemission from Graphite

Ultrasensitive Terahertz Nano‐Probing for Semiconductors Using Nanogap Structures

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