Broadband femtosecond spectroscopic ellipsometry

Richter, Steffen; Rębarz, Mateusz; Herrfurth, Oliver; Espinoza, Shirly; Schmidt‐Grund, Rüdiger; Andreasson, Jakob

doi:10.1063/5.0027219

Cited by 17 publications

(10 citation statements)

References 65 publications

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“…These discrepancies may originate from the treatment of the oxide layer, as discussed in ref. [2]. Interestingly, it seems that some parameters evolve with different rates and reach their final value faster than others (e.g., the

E_{1} + Δ_{1}

amplitude measured with

λ_{pump} = 400

nm).…”

Section: Resultsmentioning

confidence: 99%

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

Emminger

Espinoza

Richter

et al. 2022

Physica Rapid Research Ltrs

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Herein, the complex pseudodielectric function of Ge and Si from femtosecond pump–probe spectroscopic ellipsometry with 267, 400, and 800 nm pump–pulse wavelengths is analyzed by fitting analytical lineshapes to the second derivatives of the pseudodielectric function with respect to energy. This yields the critical point parameters (threshold energy, lifetime broadening, amplitude, and excitonic phase angle) of E 1 and E 1 + Δ 1 in Ge and E 1 in Si as functions of delay time. Coherent longitudinal acoustic phonon oscillations with a period of about 11 ps are observed in the transient critical point parameters of Ge. From the amplitude of these oscillations, the laser‐induced strain is found to be on the order of 0.03% for Ge measured with the 800 nm pump pulse, which is in reasonable agreement with the strain calculated from theory.

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E_{1} + Δ_{1}

amplitude measured with

λ_{pump} = 400

nm).…”

Section: Resultsmentioning

confidence: 99%

“…[1] (the instrumental setup is also described in ref. [2]); however, a quantitative analysis of the data has not been included. Therefore, the goal of this work is to quantitatively investigate the time‐resolved critical points

E_{1}

and

E_{1} + Δ_{1}

in Ge and

E_{1}

in Si using the data provided in ref.…”

Section: Introductionmentioning

confidence: 99%

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

Emminger

Espinoza

Richter

et al. 2022

Physica Rapid Research Ltrs

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“…The results of these experiments can be found elsewhere [30,37,38]. trSE measurements were performed using a femtosecond pulsed laser [10], according to Fig. 2.…”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, measurement techniques that are able to accurately investigate those effects are necessary. In recent years, time-resolved pump-probe spectroscopic ellipsometry (trSE) proved to be an excellent contestant for this with many possibilities [8][9][10][11]. Spectroscopic ellipsometry is a predestined method for obtaining optical and material properties of semiconductors as well as many other materials, due to its high accuracy and sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond pump-probe absorption edge spectroscopy of cubic GaN

Baron¹,

Goldhahn²,

Espinoza³

et al. 2022

Preprint

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Time-dependent femtosecond pump-probe spectroscopic ellipsometry studies on zincblende gallium-nitride (zb-GaN) are performed and analyzed between 2.9-3.7eV. An ultra-fast change of the absorption onset (3.23eV for zb-GaN) is observed by investigating the imaginary part of the dielectric function. The 266nm (4.66eV) pump pulses induce a large free-carrier concentration up to 4 × 10 20 cm −3 , influencing the transition energy between conduction and valence bands due to many-body effects, like band filling and band gap renormalization, up to ≈500meV. Additionally, the absorption of the pump-beam creates a free-carrier profile within the 605nm zb-GaN layer. This leads to varying optical properties from sample surface to substrate, which are taken into account by grading analysis for an accurate description of the experimental data. A temporal resolution of 100fs allows in-depth investigations of occurring ultra-fast relaxation and recombination processes. We provide a quantitative description of the free-carrier concentration and absorption onset at the sample surface as a function of relaxation, recombination, and diffusion yielding a characteristic relaxation time of 0.19ps and a recombination time of 26.1ps.

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“…The HHG source serves two stations for XUV science: 'MAC' for atomic, molecular and optical science and coherent diffractive imaging (Klimesova ´et al, 2021), and 'ELIps' for XUV materials science applications (Espinoza et al, 2020). Complementary methods for ultrafast optical spectroscopy are also available (using support lasers): transient optical absorption (Naumova et al, 2018), stimulated Raman scattering (Andrikopoulos et al, 2020), time-resolved spectroscopic ellipsometry (Richter et al, 2021) and IR (1D and 2D) spectroscopy.…”

Section: Methodsmentioning

confidence: 99%

First experiments with a water-jet plasma X-ray source driven by the novel high-power–high-repetition rate L1 Allegra laser at ELI Beamlines

Zymaková¹,

Albrecht²,

Antipenkov³

et al. 2021

J Synchrotron Radiat

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ELI Beamlines is a rapidly progressing pillar of the pan-European Extreme Light Infrastructure (ELI) project focusing on the development and deployment of science driven by high-power lasers for user operations. This work reports the results of a commissioning run of a water-jet plasma X-ray source driven by the L1 Allegra laser, outlining the current capabilities and future potential of the system. The L1 Allegra is one of the lasers developed in-house at ELI Beamlines, designed to be able to reach a pulse energy of 100 mJ at a 1 kHz repetition rate with excellent beam properties. The water-jet plasma X-ray source driven by this laser opens opportunities for new pump–probe experiments with sub-picosecond temporal resolution and inherent synchronization between pump and probe pulses.

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Broadband femtosecond spectroscopic ellipsometry

Cited by 17 publications

References 65 publications

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

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

Femtosecond pump-probe absorption edge spectroscopy of cubic GaN

First experiments with a water-jet plasma X-ray source driven by the novel high-power–high-repetition rate L1 Allegra laser at ELI Beamlines

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