Coherent Acoustic Phonon Oscillations and Transient Critical Point Parameters of Ge from Femtosecond Pump–Probe Ellipsometry

Emminger, Carola; Espinoza, Shirly; Richter, Steffen; Rębarz, Mateusz; Herrfurth, Oliver; Zahradník, Martin; Schmidt‐Grund, Rüdiger; Andreasson, Jakob; Zollner, Stefan

doi:10.1002/pssr.202200058

Cited by 4 publications

(2 citation statements)

References 42 publications

(100 reference statements)

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“…[ 286 ] The hot electrons can propagate ballistically over several μm [ 289 ] and phonons can oscillate coherently. [ 290 ] Finally, the system will relax back to equilibrium either due to radiative or nonradiative carrier recombination within, depending on the material, some tens of ps (e.g., ZnO) or up to several ns (e.g., GaP).…”

Section: Selected Scientific Key Challenges On Electronic Structure A...mentioning

confidence: 99%

“…TSE can be also applied to study various properties of optoelectronic materials like Si, Ge, InP, GaP, ZnO, GaN,and perovskite oxides. [286,[289][290][291][292][293] After exciting a semiconductor with a highintense laser beam, electrons and holes will occupy CB and VB band states, respectively. This will immediately, within some fs, cause bandgap renormalization (BGR) as expressed in the redshift of transition energies between VB and CB.…”

Section: Pv-related Electron Dynamicsmentioning

confidence: 99%

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Integration of Multijunction Absorbers and Catalysts for Efficient Solar‐Driven Artificial Leaf Structures: A Physical and Materials Science Perspective

Hannappel,

Shekarabi,

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et al. 2024

Solar RRL

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Artificial leaves could be the breakthrough technology to overcome the limitations of storage and mobility through the synthesis of chemical fuels from sunlight, which will be an essential component of a sustainable future energy system. However, the realization of efficient solar‐driven artificial leaf structures requires integrated specialized materials such as semiconductor absorbers, catalysts, interfacial passivation, and contact layers. To date, no competitive system has emerged due to a lack of scientific understanding, knowledge‐based design rules, and scalable engineering strategies. Here, we will discuss competitive artificial leaf devices for water splitting, focusing on multi‐absorber structures to achieve solar‐to‐hydrogen conversion efficiencies exceeding 15%. A key challenge is integrating photovoltaic and electrochemical functionalities in a single device. Additionally, optimal electrocatalysts for intermittent operation at photocurrent densities of 10‐20 mA cm‐2 must be immobilized on the absorbers with specifically designed interfacial passivation and contact layers, so‐called buried junctions. This minimizes voltage and current losses and prevents corrosive side reactions. Key challenges include understanding elementary steps, identifying suitable materials, and developing synthesis and processing techniques for all integrated components. This is crucial for efficient, robust, and scalable devices. Here, we discuss and report on corresponding research efforts to produce green hydrogen with unassisted solar‐driven (photo‐)electrochemical devices.This article is protected by copyright. All rights reserved.

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Section: Selected Scientific Key Challenges On Electronic Structure A...mentioning

confidence: 99%

Section: Pv-related Electron Dynamicsmentioning

confidence: 99%

Integration of Multijunction Absorbers and Catalysts for Efficient Solar‐Driven Artificial Leaf Structures: A Physical and Materials Science Perspective

Hannappel,

Shekarabi,

Jaegermann

et al. 2024

Solar RRL

View full text Add to dashboard Cite

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Eliminating noise from spectra by linear and nonlinear methods

Aspnes

2022

Thin Solid Films

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Measurement and modeling of strain waves in germanium induced by ultrafast laser pulses

Aagaard,

Julsgaard

2024

Journal of Applied Physics

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Transient reflectivity measurements are used to probe the strain waves induced by ultrashort laser pulses in bulk [100] germanium. The measurement signals are compared to purely analytical model functions based on the known material parameters for germanium. The modeling includes (i) a derivation of analytical solutions to the wave equation for strain waves coupled to the diffusion equation for heat and charge carriers and (ii) an expression for the impact on reflection coefficients that are caused by perturbations to the dielectric function but extended to cover a non-isotropic, uniaxial dielectric tensorial form. The model is held up against transient reflectivity measurements with an s- and a p-polarized probe and with a probe wavelength in the range of 502–710 nm. Excellent agreement is found when comparing the oscillatory shape of the measurement signals to the models. As for the magnitude of the oscillations, the models reproduce the overall trends of the experiment when using the previously published values for the elasto-optical tensor measured under static strain.

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Coherent Acoustic Phonon Oscillations and Transient Critical Point Parameters of Ge from Femtosecond Pump–Probe Ellipsometry

Cited by 4 publications

References 42 publications

Integration of Multijunction Absorbers and Catalysts for Efficient Solar‐Driven Artificial Leaf Structures: A Physical and Materials Science Perspective

Integration of Multijunction Absorbers and Catalysts for Efficient Solar‐Driven Artificial Leaf Structures: A Physical and Materials Science Perspective

Eliminating noise from spectra by linear and nonlinear methods

Measurement and modeling of strain waves in germanium induced by ultrafast laser pulses

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