Blue Shift of the Exciton Resonance due to Exciton-Exciton Interactions in a Multiple-Quantum-Well Structure

Peyghambarian, N.; Gibbs, H. M.; Jewell, J. L.; Antonetti, A.; Migus, A.; Hulín, D.; Mysyrowicz, A.

doi:10.1103/physrevlett.53.2433

Cited by 229 publications

(124 citation statements)

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“…with interacting bosons. Exciton-exciton interaction and the resulting exciton blueshift has been extensively studied in the 80's [30,31] and recently revisited within the framework of excitonic polaritons [32]. Polariton-polariton interaction originates from coulomb interaction between the fermionic constituents (electron and hole) of their exciton part.…”

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confidence: 99%

Polariton Laser Using Single MicropillarGaAs−GaAlAsSemiconductor Cavities

et al. 2008

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Polariton lasing is demonstrated on the zero dimensional states of single GaAs/GaAlAs micropillar cavities. Under non resonant excitation, the measured polariton ground state occupancy is found to be as large as 10 4 . Changing the spatial excitation conditions, competition between several polariton lasing modes is observed, ruling out Bose-Einstein condensation. When the polariton state occupancy increases, the emission blueshift is the signature of self-interaction within the halflight half-matter polariton lasing mode.PACS numbers: 78.55. Et, 71.36.+c, 78.45.+h Boson statistics can lead to massive occupation of a single quantum state and trigger final state stimulation. This stimulation is responsible for the bright coherent emission of light in a laser. Another fascinating property of massive bosons in thermal equilibrium is their ability to accumulate in the lowest energy state under a given critical temperature. First predicted in 1925,[1] the experimental observation of Bose Einstein condensation was achieved in the mid 1990s for ultra-cold atoms. [2,3] Demonstrating such bosonic effects with matter waves in a solid state system is very interesting both from fundamental point of view but also for applications since it could provide a new source of coherent light. Cavity polaritons are an example of quasi-particles behaving as bosons at low density. [4,5] They are the exciton-photon mixed quasi-particles arising from the strong coupling regime between quantum well (QW) excitons and a resonant optical cavity mode. Because of their very small effective mass (10 −8 times that of the hydrogen atom) cavity polaritons are expected to condensate at unusually high temperatures (up to room temperature in wide band gap microcavities).[6] These last years, massive occupation of a polariton state has been observed in semiconductor two-dimensional (2D) cavities and attributed to Bose Einstein condensation [7,8] or to polariton lasing. [9] More recently, polariton condensation has been claimed in a localized energy trap [10] where the trap dimensions are sufficiently large for the system to present a 2D continuum of polariton states. In these experiments, the clear distinction of a thermodynamic phase transition (Bose Einstein condensation) from a kinetic stimulated scattering (polariton lasing) is still debated.In this letter, we demonstrate polariton lasing in micrometric sized GaAs/GaAlAs micropillar cavities. In such zero-dimensional (0D) cavities, polariton states are confined in all directions and present a well defined discretized energy spectrum. [11,12] The absence of translation invariance lifts the wave-vector conservation selection-rules in polariton scatterings. In GaAs 2D microcavities, these selection rules are responsible for inefficient polariton-phonon or polariton-polariton scattering, preventing the build-up of a large occupancy in the lower energy states. [13,14,15,16] In this work, we show that polariton scattering is very efficient in micropillar cavities. Under non resonant excitation, a thres...

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confidence: 99%

Polariton Laser Using Single MicropillarGaAs−GaAlAsSemiconductor Cavities

et al. 2008

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“…Insight from microscopic theory reveals that the redshift observed at low excitation density mainly arises from plasma-induced bandgap renormalization and screening of the exciton binding energy. We note that the observed energy shift is much larger than those reported in conventional semiconductors such as GaAs quantum wells (-0.1 meV) [124][125][126][127][128] as a consequence of the much enhanced manybody interactions in the 2D material. Our model is further supported by the temperature dependent exciton energy shift observed in the time-resolved absorption measurements.…”

Section: Many-body Interactions In 2d Tmdsmentioning

confidence: 44%

Coherent Light-Matter Interactions in Monolayer Transition-Metal Dichalcogenides

Sie

2018

Springer Theses

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Semiconductors that are thinned down to a few atomic layers can exhibit novel properties beyond those encountered in bulk forms. Transition-metal dichalcogenides (TMDs) such as MoS 2 , WS 2 and WSe 2 are prime examples of such semiconductors. They appear in layered structure that can be reduced to a stable single layer where remarkable electronic properties can emerge. Monolayer TMDs have a pair of electronic valleys which have been proposed as a new way to carry information in next generation devices, called valleytronics. However, these valleys are normally locked in the same energy level, which limits their potential use for applications.This dissertation presents the optical methods to split their energy levels by means of coherent light-matter interactions. Experiments were performed in a pump-probe technique using a transient absorption spectroscopy on MoS 2 and WS 2 , and a newly developed XUV light source for time and angle-resolved photoemission spectroscopy (TR-ARPES) on WSe 2 and WTe 2 . Hybridizing the electronic valleys with light allows us to optically tune their energy levels in a controllable valley-selective manner. In particular, by using off-resonance circularly polarized light at small detuning, we can tune the energy level of one valley through the optical Stark effect. At larger detuning, we observe a separate contribution from the so-called Bloch-Siegert effect, a delicate phenomenon that has eluded direct observation in solids. The two effects obey opposite selection rules, which enables us to separate the two effects at two different valleys.Monolayer TMDs also possess strong Coulomb interaction that enhances many-body interactions between excitons, both bonding and non-bonding interactions. In the former, bound excitonic quasiparticles such as biexcitons play a unique role in coherent light-matter interactions where they couple the two valleys to induce opposite energy shifts. In the latter, non-bonding interactions between excitons are found to exhibit energy shifts that effectively mimics the Lennard-Jones interactions between atoms. Through these works, we demonstrate new methods to optically tune the energy levels of electronic valleys in monolayer TMDs. AcknowledgmentsFirst and foremost, I would like to thank my advisor Prof. Nuh Gedik for his mentorship and support. He has been a constant source of inspiration since I first started my graduate studies. Actually it was even before that. I remember my first meeting at a conference in Boston where he presented a real-time image of crystalline lattice motion. The idea of watching Michael Jackson performing Billie Jean flashed through my head, because he was that cool and inspiring, and he continues to be so. He has been a tremendous support since day one, where I was given the opportunity to design and build the XUV beamline for ARPES in the lab as well as the freedom to build the white-light setup next to it. His vigor to make new innovations in timeresolved experiments is always inspiring. Throughout my graduate studies, he...

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“…3, we plot a set of differential reflectivity spectra, obtained when pumping selectively at the exciton resonance, for several delay times between pump and probe pulses and at temperatures of 5 K, 10 K, and 20 K. These differential spectra all show a clear blue-shift of the exciton line. This renormalization of the exciton resonance has been extensively studied in undoped-semiconductor quantum wells [21][22][23][24] and, is attributed to short-range fermion exchange [22], which is a repulsive electron-electron and hole-hole interaction. The exciton blue-shift appears in two-dimensional semiconductors [23] because the long-range Coulomb correlation effect is strongly reduced [22].…”

Section: Resonant Excitation Of Neutral Excitonsmentioning

confidence: 99%

Many-Body Interaction Evidenced through Exciton-Trion-Electron Correlated Dynamics

et al. 2004

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Interactions among excitons, trions, and electrons are studied in CdTe modulation-doped quantum wells. These many-body interactions are investigated through the nonlinear dynamical properties in the excitonic complexes using time and spectrally resolved pump and probe techniques. This study is performed as a function of temperature and densities of excitons, trions, and electrons. The results reveal that the nonlinearities induced by trions differ from those induced by excitons and moreover they are mutually correlated. The correlated behavior of excitons and trions manifests itself by crossed trion-exciton effects. We propose that the main source of these correlations is due to the presence of electrons in the quantum well and that its physical origin is the Pauli exclusion-principle. We find that, at 5 K, trions are formed from excitons within 10 ps; at 20 K a thermal equilibrium is reached within 5 ps.

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Blue Shift of the Exciton Resonance due to Exciton-Exciton Interactions in a Multiple-Quantum-Well Structure

Cited by 229 publications

References 10 publications

Polariton Laser Using Single MicropillarGaAs−GaAlAsSemiconductor Cavities

Polariton Laser Using Single MicropillarGaAs−GaAlAsSemiconductor Cavities

Coherent Light-Matter Interactions in Monolayer Transition-Metal Dichalcogenides

Many-Body Interaction Evidenced through Exciton-Trion-Electron Correlated Dynamics

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