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

Result code in 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>

Result on the web

<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>

Result language

angličtina

Original language name

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

Original language description

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

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

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

Project

—

Continuities

R - Projekt Ramcoveho programu EK

Publication year

2025

Confidentiality

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

Name of the periodical

Journal of Applied Physics,

ISSN

0021-8979

e-ISSN

1089-7550

Volume of the periodical

138

Issue of the periodical within the volume

1

Country of publishing house

US - UNITED STATES

Number of pages

13

Pages from-to

205702 (1-13)

UT code for WoS article

001627547400001

EID of the result in the Scopus database

2-s2.0-105023120782