Hot carriers in graphene – fundamentals and applications

Massicotte, Mathieu; Soavi, Giancarlo; Principi, Alessandro; Tielrooij, Klaas‐Jan

doi:10.1039/d0nr09166a

Cited by 89 publications

(108 citation statements)

References 349 publications

(636 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We observe that the PC for low LLs does not saturate, whereas the high LL PC saturates much easier. This is consistent with our model since the PC for low LLs is mainly a sum of the electron and hole currents; whereas in the high LL regime the PC saturates much easier since it is the difference of electron and hole currents and thus bottlenecked by the difference of relaxation rates of electrons and holes [25,45]. This is evidenced by the observed markedly different saturation powers, P 0 for low and high LL ( We also see a peculiar double-bent saturation behavior which occurs predominately at high LLs, as shown in the inset of Fig.…”

Section: Discussionsupporting

confidence: 91%

“…Our work provides an unique study of carrier relaxations using a continuous excitation, which extends beyond the ultrafast regime studied in most pump-probe measurements. We believe our coherent model of PC from graphene in the quantum Hall regime will further the development of applications using graphene such as single-photon detection [46][47][48] and light-harvesting [49,50], as an electrically-measured CM has been longcoveted [25]. The quantum Hall regime can be realized with a synthetic gauge field [51].…”

Section: Discussionmentioning

confidence: 90%

“…However, a unified picture of the PC is still missing. Despite many attempts with optical methods [22][23][24], definitive evidence of CM in a Landau quantized monolayer graphene using electric measurements is still ambiguous [16,25,26]. Experimentally, PC measurements from graphene in the quantum Hall regime are commonly obscured by the sample's substantially varying impedance when sweeping the Fermi level through many LLs [27].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Chiral transport of hot carriers in graphene in the quantum Hall regime

Cao¹,

Graß²,

Gazzano³

et al. 2021

Preprint

View full text Add to dashboard Cite

Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Chiral transport of hot carriers in graphene in the quantum Hall regime

Cao¹,

Graß²,

Gazzano³

et al. 2021

Preprint

View full text Add to dashboard Cite

“… 22 , 57 Cooling via diffusion depends on the electronic heat diffusivity D , which increases with charge mobility and Fermi energy. 58 In the case of pump–probe measurements, the observed evolution of the electron temperature increase due to lateral heat diffusion depends on both pump and probe spot sizes (σ pump and σ pr , respectively), according to (see Supporting Information ): Using this equation, we calculate that, for spot sizes below 1 μm, “diffusive cooling” can become the dominant cooling channel in high-mobility graphene samples, even at room temperature. In the measurements we performed on WSe 2 -encapsulated graphene, “diffusive cooling” does not play a large role, due to the relatively large spot sizes that we used (see Figure S12 of the Supporting Information ).…”

Section: Results and Discussionmentioning

confidence: 99%

Hot-Carrier Cooling in High-Quality Graphene Is Intrinsically Limited by Optical Phonons

et al. 2021

Self Cite

View full text Add to dashboard Cite

Many promising optoelectronic devices, such as broadband photodetectors, nonlinear frequency converters, and building blocks for data communication systems, exploit photoexcited charge carriers in graphene. For these systems, it is essential to understand the relaxation dynamics after photoexcitation. These dynamics contain a sub-100 fs thermalization phase, which occurs through carrier–carrier scattering and leads to a carrier distribution with an elevated temperature. This is followed by a picosecond cooling phase, where different phonon systems play a role: graphene acoustic and optical phonons, and substrate phonons. Here, we address the cooling pathway of two technologically relevant systems, both consisting of high-quality graphene with a mobility >10 000 cm 2 V –1 s –1 and environments that do not efficiently take up electronic heat from graphene: WSe 2 -encapsulated graphene and suspended graphene. We study the cooling dynamics using ultrafast pump–probe spectroscopy at room temperature. Cooling via disorder-assisted acoustic phonon scattering and out-of-plane heat transfer to substrate phonons is relatively inefficient in these systems, suggesting a cooling time of tens of picoseconds. However, we observe much faster cooling, on a time scale of a few picoseconds. We attribute this to an intrinsic cooling mechanism, where carriers in the high-energy tail of the hot-carrier distribution emit optical phonons. This creates a permanent heat sink, as carriers efficiently rethermalize. We develop a macroscopic model that explains the observed dynamics, where cooling is eventually limited by optical-to-acoustic phonon coupling. These fundamental insights will guide the development of graphene-based optoelectronic devices.

show abstract

“…Previous studies have revealed that graphene and CNTs are excellent "hot carriers" emitters (33)(34)(35). It is well known that graphene and CNTs have unique optoelectronic properties due to their Dirac conical and gapless band structure (34,36). This allows them to absorb the laser photons efficiently and easily achieve a population inversion state because of the excitation of hot electrons and the bottleneck of the relaxation at the Dirac point.…”

Section: Resultsmentioning

confidence: 99%

Nanoalloy libraries from laser-induced thermionic emission reduction

et al. 2022

View full text Add to dashboard Cite

Nanoalloys, especially high-entropy nanoalloys (HENAs) that contain equal stoichiometric metallic elements in each nanoparticle, are widely used in vast applications. Currently, the synthesis of HENAs is challenged by slow reaction kinetics that leads to phase segregation, sophisticated pretreatment of precursors, and inert conditions that preclude scalable fabrication of HENAs. Here, we report direct conversion of metal salts to ultrafine HENAs on carbonaceous support by nanosecond pulsed laser under atmospheric conditions. Because of the unique laser-induced thermionic emission and etch on carbon, the reduced metal elements were gathered to ultrafine HENAs and stabilized by defective carbon support. This scalable, facile, and low-cost method overcomes the immiscible issue and can produce various HENAs uniformly with a size of 1 to 3 nanometers and metal elements up to 11 with productivity up to 7 grams per hour. One of the senary HENAs exhibited excellent catalytic performance in oxygen reduction reaction, manifesting great potential in practical applications.

show abstract

Hot carriers in graphene – fundamentals and applications

Abstract: Hot charge carriers in graphene exhibit fascinating physical phenomena and have great promise for exciting optoelectronic applications. The current understanding of the relevant fundamental physics and the most promising applications are reviewed.

Cited by 89 publications

References 349 publications

Chiral transport of hot carriers in graphene in the quantum Hall regime

Chiral transport of hot carriers in graphene in the quantum Hall regime

Hot-Carrier Cooling in High-Quality Graphene Is Intrinsically Limited by Optical Phonons

Nanoalloy libraries from laser-induced thermionic emission reduction

Contact Info

Product

Resources

About