Phonon-assisted luminescence of polar semiconductors: Fröhlich coupling versus deformation-potential scattering

Chernikov, A.; Bornwasser, V.; Koch, Martin; Chatterjee, Sangam; Böttge, C. N.; Feldtmann, T.; Kira, M.; Koch, Stefan; Wassner, Thomas A.; Lautenschläger, Stefan; Meyer, B. K.; Eickhoff, Martin

doi:10.1103/physrevb.85.035201

Cited by 35 publications

(35 citation statements)

References 45 publications

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“…The single-NC linewidth broadening with shell growth observed in the CdSe/CdS particles is consistent with an increased “Frölich-like” exciton-phonon interaction due to the spatial separation between the electron and hole in these quasi-type-II heterostructures [31] [32]. Our results suggest that the batch-to-batch variations in single-NC emission linewidths measured by S-PCFS originate from a delicate interplay between various parameters that affect exciton-phonon interactions within the core/shell/ligand architecture.…”

Section: Discussionmentioning

confidence: 54%

Direct probe of spectral inhomogeneity reveals synthetic tunability of single-nanocrystal spectral linewidths

et al. 2013

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The spectral linewidth of an ensemble of fluorescent emitters is dictated by a combination of the single emitter linewidths and sample inhomogeneities. For semiconductor nanocrystals, efforts to tune ensemble linewidths for optical applications have focused primarily on eliminating sample inhomogeneities because conventional single-molecule methods cannot reliably build accurate ensemble-level statistics for single-particle linewidths. Photon-correlation Fourier spectroscopy in solution (S-PCFS) offers a unique approach to investigating single-nanocrystal spectra with large sample statistics, without user selection bias, with high signal-to-noise ratios, and at fast timescales. With S-PCFS, we directly and quantitatively deconstruct the ensemble linewidth into contributions from the average single-particle linewidth and from sample inhomogeneity. We demonstrate that single-particle linewidths vary significantly from batch to batch and can be synthetically controlled. These findings crystallize our understanding of the synthetic challenges facing underdeveloped nanomaterials such as InP and InAs core/shell particles and introduce new avenues for the synthetic optimization of fluorescent nanoparticles.

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Section: Discussionmentioning

confidence: 54%

Direct probe of spectral inhomogeneity reveals synthetic tunability of single-nanocrystal spectral linewidths

et al. 2013

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“…In GaAs, these photo-excited carriers exert positive electrostatic pressure on the lattice while also increasing the temperature through thermalization, primarily by carrier-carrier scattering over tens to hundreds of fs34. During that time, the sudden changes in the valence electron populations induce lattice displacements via acoustic deformation potential coupling3536 where the presence of free carriers in the conduction band shifts the energy bandgap and exerts hydrostatic pressures whose magnitudes are proportional to the free carrier density. In TRXS measurements, structural deformation due to such high-speed lattice dynamics can be directly measured from changes of x-ray diffraction conditions.…”

Section: Trxs Experimental Results and Interpretationmentioning

confidence: 99%

“…Details of the simulations are elaborated in the Methods section as well as in our previous studies42. Generation of free carriers by SPA and TPA shifts the energy bandgap and exerts sudden hydrostatic pressure on the crystal lattice via the deformation potential scattering coefficient α p 3536, which is proportional to the carrier density n e ( z, t ). Carrier diffusion, radiative and Auger recombination, and thermal expansion also play significant roles in the evolution and transportation of strain into the crystal bulk and are incorporated into the strain model43.…”

Section: Numerical Modelingmentioning

confidence: 99%

Direct measurements of multi-photon induced nonlinear lattice dynamics in semiconductors via time-resolved x-ray scattering

Williams

Lee

Walko

et al. 2016

Sci Rep

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Nonlinear optical phenomena in semiconductors present several fundamental problems in modern optics that are of great importance for the development of optoelectronic devices. In particular, the details of photo-induced lattice dynamics at early time-scales prior to carrier recombination remain poorly understood. We demonstrate the first integrated measurements of both optical and structural, material-dependent quantities while also inferring the bulk impulsive strain profile by using high spatial-resolution time-resolved x-ray scattering (TRXS) on bulk crystalline gallium arsenide. Our findings reveal distinctive laser-fluence dependent crystal lattice responses, which are not described by previous TRXS experiments or models. The initial linear expansion of the crystal upon laser excitation stagnates at a laser fluence corresponding to the saturation of the free carrier density before resuming expansion in a third regime at higher fluences where two-photon absorption becomes dominant. Our interpretations of the lattice dynamics as nonlinear optical effects are confirmed by numerical simulations and by additional measurements in an n-type semiconductor that allows higher-order nonlinear optical processes to be directly observed as modulations of x-ray diffraction lineshapes.

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“…1,2 The resulting change in interatomic spacing is proportional to the number of free carriers generated at low intensities below the onset of nonlinear absorption. 3 Excess energy from the light can be transferred to the lattice and increases the lattice spacing by creating a thermoelastic stress.…”

mentioning

confidence: 99%

Measuring femtometer lattice displacements driven by free carrier diffusion in a polycrystalline semiconductor using time-resolved x-ray scattering

Landahl

DiChiara

et al. 2018

Applied Physics Letters

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We show that time-resolved x-ray scattering can be applied to polycrystalline materials for the measurement of carrier diffusion. A polycrystalline indium antimonide sample is prepared by high-intensity ultrafast laser surface melting and re-solidification under vacuum to create randomly oriented grains with an average size of 13 nm. Two static diffraction rings are simultaneously observed on a gated pixel array detector. Their centroids move following lower-intensity laser excitation, and utilizing an in-situ angular calibration, the transient lattice spacing is determined with femtometer accuracy, thereby allowing the measurement of charge carrier dynamics. Compared to bulk calculations, we find that carrier diffusion slows by more than one order of magnitude. This result provides evidence for the formation of potential energy barriers at the grain boundaries and demonstrates the capability of time-resolved x-ray scattering to probe nanoscale charge transport in materials other than near-perfect crystals.

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Phonon-assisted luminescence of polar semiconductors: Fröhlich coupling versus deformation-potential scattering

Cited by 35 publications

References 45 publications

Direct probe of spectral inhomogeneity reveals synthetic tunability of single-nanocrystal spectral linewidths

Direct probe of spectral inhomogeneity reveals synthetic tunability of single-nanocrystal spectral linewidths

Direct measurements of multi-photon induced nonlinear lattice dynamics in semiconductors via time-resolved x-ray scattering

Measuring femtometer lattice displacements driven by free carrier diffusion in a polycrystalline semiconductor using time-resolved x-ray scattering

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