Interlayer Bound Wannier Excitons in Germanium Sulfide

Postorino, Sara; Sun, Jianbo; Fiedler, Saskia; Lem, Laurent O. Lee Cheong; Palummo, Maurizia; Camilli, Luca

doi:10.3390/ma13163568

Cited by 4 publications

(5 citation statements)

References 54 publications

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“…Our results are in excellent agreement with the experimental bulk GeS BG energies extrapolated to 0 K given in ref 54. and 55, as well as with previous theoretical calculations with GW in ref 56. and 57.…”

supporting

confidence: 92%

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Optical properties of orthorhombic germanium sulfide: unveiling the anisotropic nature of Wannier excitons

Arfaoui,

Zawadzka,

Ayari

et al. 2023

Nanoscale

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supporting

confidence: 92%

“…54 and 55, as well as with previous theoretical calculations with GW in ref. 56 and 57. In addition, the QP corrections are slightly dispersed with respect to the KS eigenenergies.…”

Section: First-principles Calculations Of the Quasi-particle And Exci...mentioning

confidence: 98%

Optical properties of orthorhombic germanium sulfide: unveiling the anisotropic nature of Wannier excitons

Arfaoui,

Zawadzka,

Ayari

et al. 2023

Nanoscale

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show abstract

“…To estimate the strength of this Fröhlich interaction we follow the approach described in ref . We consider the presence of Wannier excitons which is confirmed by Pastorino et al showing that the wave function of the first bright exciton in GeS is highly delocalized and spreads over several atomic layers. The large spatial extension of the exciton is a further central property of forbidden LO scattering based on Fröhlich interaction and (quasi-)resonant exciton excitation.…”

mentioning

confidence: 99%

Resonant Exciton Scattering Reveals Raman Forbidden Phonon Modes in Layered GeS

Jadczak

Andrzejewski

Debus

et al. 2023

J. Phys. Chem. Lett.

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Germanium monosulfide with an anisotropic puckered crystalline structure has recently attracted much attention due to its unique optical and electronic properties; however, exciton–phonon interactions were only superficially elucidated. We study the resonant Raman scattering and the photoluminescence of the optically active Γ-exciton in layered GeS flakes and evaluate the exciton and phonon responses on variations in the excitation energy, laser-light and emission polarizations, temperature, and laser power. A double-resonance mechanism allows for observing Raman forbidden (dark) first- and second-order longitudinal-optical phonon modes whose symmetries and energies are moreover calculated by density functional perturbation theory. For (quasi)-resonant exciton excitation, the selection rules become relaxed so that a fourth-order Fröhlich intraband process is mediated by the scattering of the electron with a longitudinal-optical and an acoustic phonon. Our results demonstrate considerable coupling between phonons and photogenerated carriers in GeS flakes and the high efficiency of multiorder scattering in optical processes.

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“…42. We consider the presence of Wannier excitons which is con rmed by Pastorino et al [43] showing that the wave function of the rst bright exciton in GeS is highly delocalized and spreads over several atomic layers. The large spatial extension of the exciton is a further central property of forbidden LO scattering based on Fröhlich interaction and (quasi-)resonant exciton excitation.…”

Section: (B)mentioning

confidence: 87%

Resonant exciton scattering reveals Raman forbidden phonon modes in layered GeS

Jadczak

Andrzejewski

Debus

et al. 2023

Preprint

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Semiconducting layered group-IV monochalcogenides such as black phosphorous and germanium monosulfide with an anisotropic puckered crystalline structure in each layer have recently attracted much attention due to their unique optical and electronic properties. However, exciton-phonon interactions were only superficially elucidated, although they tremendously affect the opto-electronic operation principles and performance. We study the resonant Raman scattering and the photoluminescence of the optically active Γ-exciton in layered GeS flakes and evaluate the exciton and phonon responses on variations in the excitation energy, laser-light and emission polarizations, temperature, and laser power. The resonant Raman scattering leads to the observation of dark first- and second-order optical phonon modes whose symmetries and energies are calculated by means of a density functional perturbation theory. We reveal a double-resonance mechanism activating the Raman forbidden (dark) longitudinal-optical scattering processes: For (quasi)-resonantly exciting excitons in the GeS flakes the selection rules become relaxed so that a fourth-order Fröhlich intraband process is mediated by the scattering of the electron with a longitudinal-optical and an acoustic phonon. Our experiments demonstrate considerable coupling between phonons and photogenerated carriers in GeS flakes and the high efficiency of multi-order scattering in optical processes, and outline that layered GeS as direct band-gap semiconductor provides a promising material system for opto-electronic applications.

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Interlayer Bound Wannier Excitons in Germanium Sulfide

Cited by 4 publications

References 54 publications

Optical properties of orthorhombic germanium sulfide: unveiling the anisotropic nature of Wannier excitons

Optical properties of orthorhombic germanium sulfide: unveiling the anisotropic nature of Wannier excitons

Resonant Exciton Scattering Reveals Raman Forbidden Phonon Modes in Layered GeS

Resonant exciton scattering reveals Raman forbidden phonon modes in layered GeS

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