Laser-induced white-light emission from graphene ceramics–opening a band gap in graphene

Stręk, W.; Cichy, Bartłomiej; Radosiński, Łukasz; Głuchowski, Paweł; Marciniak, Ł.; Łukaszewicz, Mikołaj; Hreniak, D.

doi:10.1038/lsa.2015.10

Cited by 133 publications

(85 citation statements)

References 41 publications

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“…The principal advantage for such a success would be the simultaneous measurements of the photon's absorption and emission spectra in different layers of the BLG. The results of the presented paper are particularly important in the context of the recent experimental results [52,53] concerning the discovery of the laser-induced white light emission spectra in graphene ceramics. It was demonstrated in Ref.…”

Section: Resultsmentioning

confidence: 94%

Spectral properties of excitons in the bilayer graphene

Apinyan

Kopeć

2018

Physica E: Low-dimensional Systems and Nanostructures

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In this paper, we consider the spectral properties of the bilayer graphene with the local excitonic pairing interaction between the electrons and holes. We consider the generalized Hubbard model, which includes both intralayer and interlayer Coulomb interaction parameters. The solution of the excitonic gap parameter is used to calculate the electronic band structure, single-particle spectral functions, the hybridization gap, and the excitonic coherence length in the bilayer graphene. We show that the local interlayer Coulomb interaction is responsible for the semimetal-semiconductor transition in the double layer system, and we calculate the hybridization gap in the band structure above the critical interaction value. The formation of the excitonic band gap is reported as the threshold process and the momentum distribution functions have been calculated numerically. We show that in the weak coupling limit the system is governed by the Bardeen-Cooper-Schrieffer (BCS)-like pairing state. Contrary, in the strong coupling limit the excitonic condensate states appear in the semiconducting phase, by forming the Dirac's pockets in the reciprocal space.PACS numbers: 68.65. Pq, 73.22.Pr, 73.22.Gk, 71.35.Lk, 71.10.Li, 78.67.Wj, 73.30.+y INTRODUCTIONThe electronic band gap of semiconductors and insulators largely determines their optical, transport properties and governs the operation of semiconductor based devices such as p-n junctions, transistors, photodiodes and lasers [1]. Opening up a band gap in the bilayer graphene (BLG), by applying the external electric field and finding a suitable substrate are two challenges for constituting the modern nano-electronic equipment [2,3]. The imposition of external electrical field can tune the bilayer graphene from the semimetal to the semiconducting state [2]. On the other hand, the possibility of formation of the excitonic insulator state and the excitonic condensation in the bilayer graphene structures remains controversial in the modern solid state physics [4][5][6][7][8][9][10][11][12][13][14]. In difference with the quasi two-dimensional (2D) semiconducting systems, where those two states have been observed experimentally and well discussed theoretically [15][16][17][18][19][20][21][22][23][24][25][26][27], the formation of the excitonic condensate states in the BLG system, from the original electron-hole pairing states, is much more obscure because of the complicated nature of the single-particle correlations in these systems [6,8,10,13,14]. The weak correlation diagrammatic mechanism, discussed in the Refs.13, 14, is restricted only to the closed loop expansion in the diagrammatic series, and in this case, only the density fluctuation effects could affect the formation of the excitonic condensate states. Meanwhile, it has been shown [28][29][30] that even the undoped graphene can provide a variety of electron-hole type pairing chiral symmetry breaking * Corresponding author. Tel.: +48 71 3954 284; E-mail address: v.apinyan@int.pan.wroc.pl.orders especially for the strong C...

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Section: Resultsmentioning

confidence: 94%

Spectral properties of excitons in the bilayer graphene

Apinyan

Kopeć

2018

Physica E: Low-dimensional Systems and Nanostructures

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“…More recently, graphene has been identified as a material with remarkable optical and electronic properties for numerous applications [9][10][11] and has sparked interest in novel physical properties of two-dimensional (2D) materials [12,13]. 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].…”

Section: Introductionmentioning

confidence: 99%

“…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%

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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“…The results have been discussed in terms of blackbody radiation. Recent studies on light emission from graphene ceramics have shown that white-light emission may also be observed under intense laser excitation27. In the experiments, the graphene ceramics were compacted from multilayer (1–4 sheets each) graphene flakes by isostatic high pressure sintering at 8 GPa and 500 °C.…”

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confidence: 99%

Laser induced white lighting of graphene foam

Stręk¹,

Tomala²,

Łukaszewicz³

et al. 2017

Sci Rep

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Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources.

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Laser-induced white-light emission from graphene ceramics–opening a band gap in graphene

Cited by 133 publications

References 41 publications

Spectral properties of excitons in the bilayer graphene

Spectral properties of excitons in the bilayer graphene

Ultrafast Multiphoton Thermionic Photoemission from Graphite

Laser induced white lighting of graphene foam

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