Spatiotemporal carrier dynamics in graphene
Doktorsavhandling, 2019
Graphene as an atomically thin material exhibits remarkable optical and
electronic properties that suggest its technological application in novel optoelectronic
devices, such as graphene-based photodetectors and lasers. To understand
the properties of such devices on a microscopic level, we study the
interplay of optical excitation, carrier-carrier, carrier-phonon, and carrierphoton
scattering as well as diffusion processes. We apply a microscopic
model based on the density matrix formalism with spatiotemporal graphene
Bloch equations in its core. This approach provides microscopic access to
the temporally, spectrally and spatially resolved carrier dynamics both in
the presence and absence of an electric field, allowing the study of manyparticle
mechanisms behind photodetection and gain in graphene.
The focus of this thesis lies in modelling optics, dynamics and transport
phenomena on consistent microscopic footing. We predict the possibility to
achieve a stable population inversion in graphene, which is the crucial prerequisite
for using graphene as an active material in a nanolaser. Further,
we provide microscopic insights into the impact of an electric field on the
carrier dynamics revealing the appearance of an efficient dark carrier multiplication
that can even enhance the field-induced current. We also provide a
microscopic foundation for the photoconduction and the bolometric effect as
important mechanisms in a graphene based photodetector. Furthermore, we
provide insights into the spatiotemporal dynamics of optically excited carriers,
which create density and temperature gradients resulting in a diffusion
of carriers. The gained insights can be used to study the thermoelectric effect
and dynamics at interfaces of spatial inhomogeneities.
electronic properties that suggest its technological application in novel optoelectronic
devices, such as graphene-based photodetectors and lasers. To understand
the properties of such devices on a microscopic level, we study the
interplay of optical excitation, carrier-carrier, carrier-phonon, and carrierphoton
scattering as well as diffusion processes. We apply a microscopic
model based on the density matrix formalism with spatiotemporal graphene
Bloch equations in its core. This approach provides microscopic access to
the temporally, spectrally and spatially resolved carrier dynamics both in
the presence and absence of an electric field, allowing the study of manyparticle
mechanisms behind photodetection and gain in graphene.
The focus of this thesis lies in modelling optics, dynamics and transport
phenomena on consistent microscopic footing. We predict the possibility to
achieve a stable population inversion in graphene, which is the crucial prerequisite
for using graphene as an active material in a nanolaser. Further,
we provide microscopic insights into the impact of an electric field on the
carrier dynamics revealing the appearance of an efficient dark carrier multiplication
that can even enhance the field-induced current. We also provide a
microscopic foundation for the photoconduction and the bolometric effect as
important mechanisms in a graphene based photodetector. Furthermore, we
provide insights into the spatiotemporal dynamics of optically excited carriers,
which create density and temperature gradients resulting in a diffusion
of carriers. The gained insights can be used to study the thermoelectric effect
and dynamics at interfaces of spatial inhomogeneities.
spatiotemporal dynamics
density matrix formalism
graphene
relaxation dynamics
carrier multiplication
Bloch equations
photoconduction effect
bolometric effect
PJ-salen, Origo, Kemigården 1, Göteborg
Opponent: Professor Doris Reiter, Institute for Solid State Physics, University of Münster, Germany
Författare
Roland Jago
Chalmers, Fysik, Kondenserade materiens teori
Roland Jago, Raül Perea-Causin, Samuel Brem, and Ermin Malic Spatio-temporal dynamics in graphene
Microscopic origin of the bolometric effect in graphene
Physical Review B,; Vol. 99(2019)
Artikel i vetenskaplig tidskrift
Microscopic understanding of the photoconduction effect in graphene
Physical Review B,; Vol. 96(2017)p. Article no 085431 -
Artikel i vetenskaplig tidskrift
Current enhancement due to field-induced dark carrier multiplication in graphene
2D Materials,; Vol. 4(2017)
Artikel i vetenskaplig tidskrift
Recombination channels in optically excited graphene
Physica Status Solidi (B): Basic Research,; Vol. 252(2015)p. 2456-2460
Artikel i vetenskaplig tidskrift
Graphene as gain medium for broadband lasers
Physical Review B - Condensed Matter and Materials Physics,; Vol. 92(2015)
Artikel i vetenskaplig tidskrift
B. Semnani, R. Jago, S. Safavi-Naeini. A. H. Majedi, E. Malic, and P. Tassin Anomalous optical saturation of low-energy Dirac states in graphene and its implication for nonlinear optics
Unconventional double-bended saturation of carrier occupation in optically excited graphene due to many-particle interactions
Nature Communications,; Vol. 8(2017)
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Carrier Dynamics in Graphene: Ultrafast Many-Particle Phenomena
Annalen der Physik,; Vol. 529(2017)
Artikel i vetenskaplig tidskrift
Ultrafast momentum imaging of pseudospin-flip excitations in graphene
Physical Review B,; Vol. 96(2017)
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Experimentally accessible signatures of Auger scattering in graphene
Physical Review B: covering condensed matter and materials physics,; Vol. 94(2016)p. 235430-
Artikel i vetenskaplig tidskrift
Graphene as an atomically thin material exhibits remarkable optical and
electronic properties that suggests its technological application in novel op-
toelectronic devices, such as graphene-based lasers and photodetectors. We
show that it is possible to achieve a stable population inversion in graphene,
which is crucial for using graphene as an active material in a nanolaser.
Depending on the experimental conditions there are different mechanisms de-
termining the optical response and the resulting photocurrent. In this thesis
we provide microscopic insights into the photoconduction and the bolometric effect as
important mechanisms in a graphene based photodetector. With our
research we are able to identify microscopic knobs to tune the photocurrent.
Furthermore, we study the interplay of the carrier relaxation and transport
phenomena. We reveal that in the presence of an external electric field an efficient dark carrier multiplication occur, which increses the carrier density,
and even enhance the field-induced current. Moreover, we provide a micro-
scopic description of the spatiotemporal dynamics of optically excited carri-
ers, which create density and temperature gradients resulting in a diffusion
of carriers.
electronic properties that suggests its technological application in novel op-
toelectronic devices, such as graphene-based lasers and photodetectors. We
show that it is possible to achieve a stable population inversion in graphene,
which is crucial for using graphene as an active material in a nanolaser.
Depending on the experimental conditions there are different mechanisms de-
termining the optical response and the resulting photocurrent. In this thesis
we provide microscopic insights into the photoconduction and the bolometric effect as
important mechanisms in a graphene based photodetector. With our
research we are able to identify microscopic knobs to tune the photocurrent.
Furthermore, we study the interplay of the carrier relaxation and transport
phenomena. We reveal that in the presence of an external electric field an efficient dark carrier multiplication occur, which increses the carrier density,
and even enhance the field-induced current. Moreover, we provide a micro-
scopic description of the spatiotemporal dynamics of optically excited carri-
ers, which create density and temperature gradients resulting in a diffusion
of carriers.
Infrastruktur
C3SE (Chalmers Centre for Computational Science and Engineering)
Ämneskategorier
Atom- och molekylfysik och optik
Annan fysik
Den kondenserade materiens fysik
ISBN
978-91-7905-100-6
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4567
Utgivare
Chalmers
PJ-salen, Origo, Kemigården 1, Göteborg
Opponent: Professor Doris Reiter, Institute for Solid State Physics, University of Münster, Germany