Transient dielectric function and carrier related processes in doped cubic GaN determined by femtosecond pump-probe spectroscopic ellipsometry

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F10974938%3A_____%2F25%3A25_88_25" target="_blank" >RIV/10974938:_____/25:25_88_25 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1063/5.0281902" target="_blank" >https://doi.org/10.1063/5.0281902</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1063/5.0281902" target="_blank" >10.1063/5.0281902</a>

Result language

angličtina

Original language name

Transient dielectric function and carrier related processes in doped cubic GaN determined by femtosecond pump-probe spectroscopic ellipsometry

Original language description

We employ time-resolved spectroscopic ellipsometry to determine the transient dielectric function of cubic GaN for delay-times between 200 fs and 4 ns after excitation. This pump and probe based technique uses a high energy laser pulse (266 nm, 35 fs fundamental pulse duration) to generate large electron-hole pair concentrations. These electrons relax down into the conduction band minimum with a characteristic relaxation time of 0.19 ps. The resulting phase-space band filling leads to a blue shift of the absorption edge, visible in the dielectric function for each delay-time. The greatest shift of the absorption edge is observed after approximate to 1 ps. Afterward, the free-electron concentration in the conduction band minimum decreases due to recombination and diffusion. After approximate to 100 ps, the absorption edge has nearly recovered into the steady-state case. In this study, we systematically investigate both doped cubic GaN and the effect of changing the pump intensity. This leads to a shift of the absorption edge between 200 and 500 meV for low and high pump intensities, respectively. Our analysis accounts for a free-carrier gradient within the cubic GaN (induced by the pump-pulse absorption), as well as the relaxation, recombination, and diffusion processes. More than 130 individual spectra are analyzed by the same modeling procedure to provide an objective comparison between different samples and pump power densities. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(https://creativecommons.org/licenses/by/4.0/)

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

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2025

Confidentiality

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

Name of the periodical

J. Applied Physics

ISSN

0021-8979

e-ISSN

1089-7550

Volume of the periodical

138

Issue of the periodical within the volume

12

Country of publishing house

US - UNITED STATES

Number of pages

8

Pages from-to

125702

UT code for WoS article

001578830000001

EID of the result in the Scopus database

2-s2.0-105016573119