Coherent acoustic phonon oscillations and transient critical point parameters of Ge from femtosecond pump‐probe ellipsometryShow others and affiliations
2022 (English)In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 16, no 7, article id 2200058Article in journal (Refereed) Published
Abstract [en]
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.
Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2022. Vol. 16, no 7, article id 2200058
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:liu:diva-185207DOI: 10.1002/pssr.202200058ISI: 000804607300001Scopus ID: 2-s2.0-85131056773OAI: oai:DiVA.org:liu-185207DiVA, id: diva2:1659062
Funder
German Research Foundation (DFG)European Regional Development Fund (ERDF)2022-05-182022-05-182023-02-17Bibliographically approved