Impact of Auger processes on carrier dynamics in graphene

@article{Winzer2012ImpactOA,
  title={Impact of Auger processes on carrier dynamics in graphene},
  author={T. Winzer and E. Malic},
  journal={Physical Review B},
  year={2012},
  volume={85},
  pages={241404}
}
Auger processes are of great importance for both fundamental research and technological applications, since they change the number of charge carriers in a system. Here, we present a microscopic study on the influence of Auger relaxation channels on the carrier dynamics in graphene. The presented time-, momentum-, and angle-resolved calculations reveal the importance of the impact excitation giving rise to a significant multiplication of optically excited carriers and a remarkable Coulomb… Expand

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References

SHOWING 1-10 OF 47 REFERENCES
Carrier multiplication in graphene.
TLDR
It is shown, based on microscopic calculations within the density matrix formalism, that Auger processes do play an unusually strong role for the relaxation dynamics of photoexcited charge carriers in graphene, confirming the potential of graphene as a new material for high-efficiency photodevices. Expand
Very slow cooling dynamics of photoexcited carriers in graphene observed by optical-pump terahertz-probe spectroscopy.
TLDR
The model, which includes intraband carrier scattering and interband carrier recombination and generation, agrees very well with the experimental observations and is interpreted as resulting from the cooling of the photoexcited carriers via phonon emission. Expand
Ultrafast relaxation dynamics of hot optical phonons in graphene
Using ultrafast optical pump-probe spectroscopy, we study the relaxation dynamics of hot optical phonons in few-layer and multilayer graphene films grown by epitaxy on silicon carbide substrates andExpand
Slowing hot-carrier relaxation in graphene using a magnetic field
A degenerate pump-probe technique is used to investigate the nonequilibrium carrier dynamics in multilayer graphene. Two distinctly different dynamics of the carrier relaxation are observed. A fastExpand
Can impact excitation explain efficient carrier multiplication in carbon nanotube photodiodes?
TLDR
This work proposes a detailed mechanism based on carrier dynamics and impact excitation resulting in highly efficient multiplication of electron-hole pairs in carbon nanotube photodiodes at photon energies near the carrier multiplication threshold (twice the quasi-particle band gap). Expand
Ultrafast nonequilibrium carrier dynamics in a single graphene layer
Nonequilibrium carrier dynamics in single exfoliated graphene layers on muscovite substrates are studied by ultrafast optical pump-probe spectroscopy and compared with microscopic theory. The veryExpand
Carrier relaxation in epitaxial graphene photoexcited near the Dirac point.
TLDR
The experiments complemented by microscopic modeling reveal that the carrier relaxation is significantly slowed down as the photon energy is tuned to values below the optical-phonon frequency; however, owing to the presence of hot carriers, optical-Phonon emission is still the predominant relaxation process. Expand
Ultrafast Dynamics of Carrier Multiplication in Quantum Dots
A quantum-kinetic approach to the ultrafast dynamics of carrier multiplication in semiconductor quantum dots is presented. We investigate the underlying dynamics in the electronic subband occupationsExpand
High efficiency carrier multiplication in PbSe nanocrystals: implications for solar energy conversion.
TLDR
It is demonstrated for the first time that impact ionization (II) (the inverse of Auger recombination) occurs with very high efficiency in semiconductor nanocrystals (NCs) and can be used to considerably increase the power conversion efficiency of NC-based solar cells. Expand
Auger ionization in armchair-edge graphene nanoribbons
Free electron-hole (e-h) pair generation from excitons in armchair-edged graphene nanoribbons (AGNRs) is theoretically investigated. We consider the generation of free e-h pairs by the AugerExpand
...
1
2
3
4
5
...