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

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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/)

Název v anglickém jazyce

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

Popis výsledku anglicky

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/)

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

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

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

Rok uplatnění

2025

Kód důvěrnosti údajů

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

Název periodika

J. Applied Physics

ISSN

0021-8979

e-ISSN

1089-7550

Svazek periodika

138

Číslo periodika v rámci svazku

12

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

8

Strana od-do

125702

Kód UT WoS článku

001578830000001

EID výsledku v databázi Scopus

2-s2.0-105016573119