Photoluminescence dynamics in GaAs along an optically induced Mott transition

Amo, A.; Martín, María Dolores; Viña, L.; Toropov, A. I.; Журавлев, К. С.

doi:10.1063/1.2722786

Cited by 20 publications

(11 citation statements)

References 24 publications

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“…Such a determination is usually achieved based on an analysis of the PL spectra (see, for instance, Refs. [43][44][45] rather than on simple estimates using the energy fluence per pulse. However, the direct applications of these methods is hindered by the large broadening of the PL from the GaAs core of our nanowires.…”

Section: Resultsmentioning

confidence: 99%

Exciton dynamics in GaAs/(Al,Ga)As core-shell nanowires with shell quantum dots

Corfdir¹,

Küpers²,

Lewis³

et al. 2016

Phys. Rev. B

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We study the dynamics of excitons in GaAs/(Al,Ga)As core-shell nanowires by continuous-wave and timeresolved photoluminescence and photoluminescence excitation spectroscopy. Strong Al segregation in the shell of the nanowires leads to the formation of Ga-rich inclusions acting as quantum dots. At 10 K, intense light emission associated with these shell quantum dots is observed. The average radiative lifetime of excitons confined in the shell quantum dots is 1.7 ns. We show that excitons may tunnel toward adjacent shell quantum dots and nonradiative point defects. We investigate the changes in the dynamics of charge carriers in the shell with increasing temperature, with particular emphasis on the transfer of carriers from the shell to the core of the nanowires. We finally discuss the implications of carrier localization in the (Al,Ga)As shell for fundamental studies and optoelectronic applications based on core-shell III-As nanowires. arXiv:1603.01111v3 [cond-mat.mes-hall]

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Section: Resultsmentioning

confidence: 99%

Exciton dynamics in GaAs/(Al,Ga)As core-shell nanowires with shell quantum dots

Corfdir¹,

Küpers²,

Lewis³

et al. 2016

Phys. Rev. B

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“…However, within a small region in the phase diagram at low exciton binding energy, we also find bistability, which would correspond to a sudden transformation of the exciton gas into the electron-hole liquid without phase-separation. We mentioned that experimentally there are both evidences of continuos exciton Mott transitions, i.e., phase separation [11,13,14,28], as well as of discontinuous ones [6,7,9,10,35,63,65]. The discriminant parameter might well be the exciton binding energy E ex , as we do find, since a discontinuous transition is mostly observed in bulk semiconductors, while a continuous one in confined geometries, like quantum wells, where E ex is supposedly larger.…”

Section: Discussionmentioning

confidence: 99%

Exciton Mott transition revisited

Guerci

Capone

Fabrizio

2019

Phys. Rev. Materials

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The dissociation of excitons into a liquid of holes and electrons in photoexcited semiconductors, despite being one of the first recognized examples of a Mott transition, still defies a complete understanding, especially regarding the nature of the transition, which is found continuous in some cases and discontinuous in others. Here we consider an idealized model of photoexcited semiconductors that can be mapped onto a spin-polarised half-filled Hubbard model, whose phase diagram reproduces most of the phenomenology of those systems and uncovers the key role of the exciton binding energy in determining the nature of the exciton Mott transition. We find indeed that the transition changes from discontinuous to continuous as the binding energy increases. Moreover, we uncover a rather anomalous electron-hole liquid phase next to the transition, which still sustains excitonic excitations despite being a degenerate Fermi liquid of heavy mass quasiparticles. arXiv:1810.01843v2 [cond-mat.str-el]

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“…With increasing excitation, (i) a decrease of the excitonic absorption peak, (ii) an increase of the linewidth and (iii) a weak shift of the exciton peak to lower energies appear. In [42], we have reported that this shift turns to higher energies, if the temperature is decreased down to T = 5 K. It is an advantage of our spectral investigation of the Mott transition in comparison with investigations of the dynamics of the PL in [32][33][34][35][36][37][38] that we are able to address single electron-hole pair states in the optical response over the whole spectrum. In order to analyze the spectra in more detail, we have marked the maximum and the half-maximum absorption at the exciton left part, which are considered in figure 7.…”

Section: Semiconductor Bloch Equations-the Spectral Approachmentioning

confidence: 93%

“…The unbroken interest in the experimental verification of the Mott transition manifests itself in a series of papers, where the buildup of excitons was investigated in the time-resolved photoluminescence (PL) [32][33][34][35][36][37][38]. Here, the question of how the optically induced coherent polarization is transferred into an incoherent exciton population was considered.…”

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confidence: 99%

Mott transition of excitons in GaAs-GaAlAs quantum wells

2012

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We investigate the breakup of bound electron-hole pairs, known as Mott transition of excitons, in GaAs-GaAlAs quantum wells with increasing excitation, comparing two different theoretical approaches. Firstly, a thermodynamic approach is used to investigate the ionization equilibrium between electrons, holes and excitons, where the abrupt jump of the degree of ionization from 0 to 1 indicates the Mott density. It is extended to a self-consistent quasi-particle approximation (QPA) for the carrier properties, including dynamical screening of the Coulomb interaction between carriers. Secondly, a spectral approach based on the semiconductor Bloch equations within linear optical response is used, considering the quasi-particle (QP) properties of carriers and the dynamical screening between electron-hole pairs. While the first is effectively a one-particle approach, in the second the whole twoparticle spectrum is analyzed. Within the thermodynamic approach, a simple criterion for the Mott transition can be given: namely, if the sum of chemical potentials of carriers, reflecting the effective shrinkage of the band edge, crosses the exciton energy with increasing excitation. We demonstrate that this simple picture cannot be maintained in the two-particle approach. Here, a compact quantity, which describes the behavior of the band edge, does not exist. In fact, the behavior of the single states in the spectrum is generated by the interplay of dynamical screening in the interband self-energy and the effective interaction of the electron-hole pairs. Moreover, the band edge cannot be clearly resolved, 2 since it is merged with excited exciton states (e.g. 2s state), which show up only for densities far below the Mott density. Instead of a Mott density, only a density range can be given, where the Mott transition appears. We demonstrate that a small damping as a prerequisite for the validation of the extended QPA in the thermodynamic approach breaks down, analyzing (i) the dephasing processes with increasing excitation, (ii) the strong increase of the excitonic linewidth and (iii) comparing with the lifetime of carriers in the QP description. Contents

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Photoluminescence dynamics in GaAs along an optically induced Mott transition

Cited by 20 publications

References 24 publications

Exciton dynamics in GaAs/(Al,Ga)As core-shell nanowires with shell quantum dots

Exciton dynamics in GaAs/(Al,Ga)As core-shell nanowires with shell quantum dots

Exciton Mott transition revisited

Mott transition of excitons in GaAs-GaAlAs quantum wells

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