Direct View of Hot Carrier Dynamics in Graphene
Jens Christian Johannsen,Søren Ulstrup,Federico Cilento,Alberto Crepaldi,Michele Zacchigna,Cephise Cacho,I. C. Edmond Turcu,Emma Springate,Felix Fromm,Christian Raidel,Thomas Seyller,Fulvio Parmigiani,Marco Grioni,Philip Hofmann +13 more
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TLDR
A dynamical view on the Dirac cone is presented by time- and angle-resolved photoemission spectroscopy to show the quasi-instant thermalization of the electron gas to a temperature of ≈2000 K, and to disentangle the subsequent decay into excitations of optical phonons and acoustic phonons.Abstract:
The ultrafast dynamics of excited carriers in graphene is closely linked to the Dirac spectrum and plays a central role for many electronic and optoelectronic applications. Harvesting energy from excited electron-hole pairs, for instance, is only possible if these pairs can be separated before they lose energy to vibrations, merely heating the lattice. Until now, the hot carrier dynamics in graphene could only be accessed indirectly. Here, we present a dynamical view on the Dirac cone by time-and angle-resolved photoemission spectroscopy. This allows us to show the quasi-instant thermalization of the electron gas to a temperature of approximate to 2000 K, to determine the time-resolved carrier density, and to disentangle the subsequent decay into excitations of optical phonons and acoustic phonons (directly and via supercollisions).read more
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Photodetectors based on graphene, other two-dimensional materials and hybrid systems
Frank H. L. Koppens,Thomas Mueller,Phaedon Avouris,Andrea C. Ferrari,Miriam S. Vitiello,Marco Polini +5 more
TL;DR: An overview and evaluation of state-of-the-art photodetectors based on graphene, other two-dimensional materials, and hybrid systems based on the combination of differentTwo-dimensional crystals or of two- dimensional crystals and other (nano)materials, such as plasmonic nanoparticles, semiconductors, quantum dots, or their integration with (silicon) waveguides are provided.
Journal ArticleDOI
Observation of the Dirac fluid and the breakdown of the Wiedemann-Franz law in graphene
Jesse Crossno,Jing K. Shi,Ke Wang,Xiaomeng Liu,Achim Harzheim,Andrew Lucas,Subir Sachdev,Subir Sachdev,Philip Kim,Takashi Taniguchi,Kenji Watanabe,Thomas A. Ohki,Kin Chung Fong +12 more
TL;DR: Employing high-sensitivity Johnson noise thermometry, an order of magnitude increase in the thermal conductivity and the breakdown of the Wiedemann-Franz law is reported in the thermally populated charge-neutral plasma in graphene, a signature of the Dirac fluid and constitutes direct evidence of collective motion in a quantum electronic fluid.
Journal ArticleDOI
Multifunctional Energy Storage and Conversion Devices
TL;DR: Smart energy devices are defined to be energy devices that are responsive to changes in configurational integrity, voltage, mechanical deformation, light, and temperature, called self-healability, electrochromism, shape memory, photodetection, and thermal responsivity.
Journal ArticleDOI
Snapshots of non-equilibrium Dirac carrier distributions in graphene
Isabella Gierz,Jesse C. Petersen,Jesse C. Petersen,Matteo Mitrano,Cephise Cacho,Edmond Turcu,Emma Springate,Alexander Stöhr,Axel Kohler,Ulrich Starke,Andrea Cavalleri,Andrea Cavalleri +11 more
TL;DR: In this article, the authors used time and angle-resolved photo-emission spectroscopy with femtosecond extreme-ultraviolet pulses to directly probe the non-equilibrium response of Dirac electrons near the K-point of the Brillouin zone.
Journal ArticleDOI
Snapshots of non-equilibrium Dirac carrier distributions in graphene
Isabella Gierz,Jesse C. Petersen,Jesse C. Petersen,Matteo Mitrano,Cephise Cacho,Edmond Turcu,Emma Springate,Alexander Stöhr,Axel Kohler,Ulrich Starke,Andrea Cavalleri,Andrea Cavalleri +11 more
TL;DR: Time- and angle-resolved photoemission spectroscopy with femtosecond extreme-ultraviolet pulses are used to directly probe the non-equilibrium response of Dirac electrons near the K-point of the Brillouin zone, and no indication of carrier multiplication is found, questioning the applicability of graphene for light harvesting.
References
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