Transient dielectric functions of Ge, Si, and InP from femtosecond pump-probe ellipsometry
Journal article, 2019
Transient dielectric functions with a 120 fs time resolution of Ge, Si, and InP were acquired from 1.7 to 3.5eV with a femtosecond pump-probe rotating-compensator ellipsometer. The intensity of the pump laser (with 1.55, 3.10, or 4.65eV photon energy) was adjusted to create an initial near-surface carrier density of 10(20)cm(-3). In Ge, there is a significant (similar to 15%) decrease in the E-1 and E-1+Delta(1) critical point absorption and a Kramers-Kronig consistent change in the refractive index because photoexcited electrons at L block these transitions and reduce their amplitudes. Only a small redshift of the E-1 critical point is observed, which we attribute to lattice heating and exchange-correlation effects. Minimal changes were found for Si and InP, where electrons near Delta and Gamma do not participate in interband transitions between 1.7 and 3.5eV.
Author
Shirly Espinoza
J. Heyrovsky Institute of Physical Chemistry of the CAS
Steffen Richter
Leipzig University
J. Heyrovsky Institute of Physical Chemistry of the CAS
Mateusz Rebarz
J. Heyrovsky Institute of Physical Chemistry of the CAS
Oliver Herrfurth
Leipzig University
Ruediger Schmidt-Grund
Leipzig University
Jakob Andreasson
Chalmers, Physics, Materials Physics
Stefan Zollner
New Mexico State University
J. Heyrovsky Institute of Physical Chemistry of the CAS
Applied Physics Letters
0003-6951 (ISSN) 1077-3118 (eISSN)
Vol. 115 5 052105Subject Categories
Atom and Molecular Physics and Optics
Other Physics Topics
Condensed Matter Physics
DOI
10.1063/1.5109927