Band filling and relaxation effects in the transient dielectric function of Ge

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F10974938%3A_____%2F25%3A25_88_32" target="_blank" >RIV/10974938:_____/25:25_88_32 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1063/5.0295255" target="_blank" >https://doi.org/10.1063/5.0295255</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1063/5.0295255" target="_blank" >10.1063/5.0295255</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Band filling and relaxation effects in the transient dielectric function of Ge

Popis výsledku v původním jazyce

This study investigates the transient dielectric function of germanium at charge carrier densities of the order of 1020 cm�3 using time�resolved spectroscopic ellipsometry. By employing a pump-probe technique, we explore the temporal evolution of the critical points E1 and E1 þ Δ1 after high-intensity laser excitation. Given the two-dimensional character of these critical points, the absorption of Ge is signifi�cantly enhanced by excitonic binding. Furthermore, at high carrier densities, intervalley scattering and band saturation play a significant role in the optical response of the material. To address these phenomena, we combined band-filling effects with a two-dimensional excitonic line shape to model the observed optical spectra. We also simulated the Fermi energies and electron temperatures governing the measure�ments using Fermi–Dirac statistics. Given the short timescales of the carrier relaxation and intervalley scattering, this analysis focuses exclu�sively on the first few picoseconds after excitation, with a minimum step size of 50 fs. The model successfully reproduces the main features of the experimental spectra, capturing the reduction in amplitude of the dielectric function and the redshift of the critical points due to bandgap renormalization. From these fits, we extract an energy relaxation rate of the order of 1:5 meV fs�1 and provide a quantitative description of the ultrafast carrier dynamics in Ge

Název v anglickém jazyce

Band filling and relaxation effects in the transient dielectric function of Ge

Popis výsledku anglicky

This study investigates the transient dielectric function of germanium at charge carrier densities of the order of 1020 cm�3 using time�resolved spectroscopic ellipsometry. By employing a pump-probe technique, we explore the temporal evolution of the critical points E1 and E1 þ Δ1 after high-intensity laser excitation. Given the two-dimensional character of these critical points, the absorption of Ge is signifi�cantly enhanced by excitonic binding. Furthermore, at high carrier densities, intervalley scattering and band saturation play a significant role in the optical response of the material. To address these phenomena, we combined band-filling effects with a two-dimensional excitonic line shape to model the observed optical spectra. We also simulated the Fermi energies and electron temperatures governing the measure�ments using Fermi–Dirac statistics. Given the short timescales of the carrier relaxation and intervalley scattering, this analysis focuses exclu�sively on the first few picoseconds after excitation, with a minimum step size of 50 fs. The model successfully reproduces the main features of the experimental spectra, capturing the reduction in amplitude of the dielectric function and the redshift of the critical points due to bandgap renormalization. From these fits, we extract an energy relaxation rate of the order of 1:5 meV fs�1 and provide a quantitative description of the ultrafast carrier dynamics in Ge

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Projekt

—

Návaznosti

R - Projekt Ramcoveho programu EK

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Applied Physics,

ISSN

0021-8979

e-ISSN

1089-7550

Svazek periodika

138

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

13

Strana od-do

205702 (1-13)

Kód UT WoS článku

001627547400001

EID výsledku v databázi Scopus

2-s2.0-105023120782