Experimentally accessible signatures of Auger scattering in graphene

Winzer, Torben; Jago, Roland; Malić, Ermin

doi:10.1103/physrevb.94.235430

Cited by 15 publications

(17 citation statements)

References 26 publications

(34 reference statements)

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“…We have shown that a model used for the Auger neutralization involving the filling of a hole in an incident ion can also predict the decay of the hole in the valence band of a homogeneous material, and the model has allowed us to estimate the branching ratio for the Auger decay of valence holes in graphene. The finding that the Auger decay of the valence hole happens more than 80% of the time correlates well with earlier results on the prominence of the Auger-like processes in the graphene valence band resulting in hole multiplication 22 . Extending our measurements to other materials (like Si) will allow us to test theories of Auger relaxation in the valence band that are important in modelling fluorescence droop 23 and charge multiplication 24 in semiconductors.…”

Section: Discussionsupporting

confidence: 91%

“…The finding that the Auger decay of the valence hole happens more than 80% of the time correlates well with earlier results on the prominence of the Auger-like processes in the graphene valence band resulting in hole multiplication22. Extending our measurements to other materials (like Si) will allow us to test theories of Auger relaxation in the valence band that are important in modelling fluorescence droop23 and charge multiplication24 in semiconductors.…”

Section: Discussionsupporting

confidence: 86%

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Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation

et al. 2017

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Auger processes involving the filling of holes in the valence band are thought to make important contributions to the low-energy photoelectron and secondary electron spectrum from many solids. However, measurements of the energy spectrum and the efficiency with which electrons are emitted in this process remain elusive due to a large unrelated background resulting from primary beam-induced secondary electrons. Here, we report the direct measurement of the energy spectra of electrons emitted from single layer graphene as a result of the decay of deep holes in the valence band. These measurements were made possible by eliminating competing backgrounds by employing low-energy positrons (<1.25 eV) to create valence-band holes by annihilation. Our experimental results, supported by theoretical calculations, indicate that between 80 and 100% of the deep valence-band holes in graphene are filled via an Auger transition.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 86%

Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation

et al. 2017

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“…Few studies have used optical pump with energies lower than optical phonon energy and reported significant slowing of the carrier relaxation 16 . However, owing to the excitation of a large density of hot carriers, optical phonon emission remained the predominant relaxation channel 11,17 . In spite of intensive work, the investigation of recombination dynamic for carriers at low photon energy and fluence remains elusive in graphene, notably under dc bias control.…”

mentioning

confidence: 99%

Ultra-long carrier lifetime in neutral graphene-hBN van der Waals heterostructures under mid-infrared illumination

et al. 2020

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Graphene/hBN heterostructures are promising active materials for devices in the THz domain, such as emitters and photodetectors based on interband transitions. Their performance requires long carrier lifetimes. However, carrier recombination processes in graphene possess sub-picosecond characteristic times for large non-equilibrium carrier densities at high energy. An additional channel has been recently demonstrated in graphene/hBN heterostructures by emission of hBN hyperbolic phonon polaritons (HPhP) with picosecond decay time. Here, we report on carrier lifetimes in graphene/hBN Zener-Klein transistors of 30 ps for photoexcited carriers at low density and energy, using mid-infrared photoconductivity measurements. We further demonstrate the switching of carrier lifetime from 30 ps (attributed to interband Auger) down to a few picoseconds upon ignition of HPhP relaxation at finite bias and/or with infrared excitation power. Our study opens interesting perspectives to exploit graphene/hBN heterostructures for THz lasing and highly sensitive THz photodetection as well as for phonon polariton optics.

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“…When pump laser fluences is > 1 mW mm -2 , the scattered electron occupation close to the charge neutrality point (0.37-0.42 eV, Fig. 4a) and the upshift of a fraction of hot-electrons to the energies comparable to SBH (E > hvpump) are clear indications of Auger recombination (AR) 26 . In this fluence regime, the combination of impact excitation dominated in the initial tens of femtoseconds and AR prevailed subsequently result in a large pool of hot-electrons with energies near SBH ( ) (Fig.…”

mentioning

confidence: 99%

Macroscopic Assembled Graphene for Silicon Mid-Infrared Photodetectors

Gao¹,

Li²,

Du³

et al. 2020

Preprint

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Graphene with linear energy dispersion and weak electron-phonon interaction is highly anticipated to harvest hot-electrons in a broad wavelength range from ultraviolet to terahertz. However, the limited absorption (~2.3%) and serious backscattering of hot-electrons associated with single-layer graphene result in inadequate quantum yields, impeding their practically broadband photodetection, especially in the mid-infrared range. Here, we report a macroscopic assembled graphene (MAG)/silicon heterojunction for ultrafast mid-infrared photodetection. The highly crystalline 2-inch scale MAG with tunable thickness from 10 to 60 nm is produced by scalable wet-assembly of commercial graphene oxide followed by thermal annealing. The MAG/Si Schottky diode exhibits broadband photodetection capability in 1-10 μm at room temperature with fast response (120-130 ns, 4 mm2 window) and high detectivity (1011 to 106 Jones), outperforming single-layer graphene/Si photodetectors by 2 to 8 orders in transient photocurrent. This optoelectronic performance is attributed to the superior advantages of MAG (~40% of light absorption, ~23 ps of carrier relaxation time, and high quasi-equilibrated hot-carrier-multiplication gain), atomic-scale contact interface of MAG and silicon, and impact-ionization avalanche gain (~100 times) from silicon. The MAG provides a long-range platform to understand the hot-carrier dynamics in stacked 2D materials, leading to next-generation broadband silicon-based image sensors.

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Experimentally accessible signatures of Auger scattering in graphene

Cited by 15 publications

References 26 publications

Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation

Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation

Ultra-long carrier lifetime in neutral graphene-hBN van der Waals heterostructures under mid-infrared illumination

Macroscopic Assembled Graphene for Silicon Mid-Infrared Photodetectors

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