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- Title
Optical and Thermal Behavior of Germanium Thin Films under Femtosecond Laser Irradiation.
- Authors
Abdelmalek, Ahmed; Kotsedi, Lebogang; Bedrane, Zeyneb; Amara, El-Hachemi; Girolami, Marco; Maaza, Malik
- Abstract
In this study, we theoretically investigate the response of a germanium thin film under femtosecond pulsed laser irradiation. Electron and lattice temperatures, as well as material-specific optical properties such as dielectric function and reflectivity, were calculated during the irradiation using an extended two-temperature model coupled with the carrier density rate equation and the Drude model. Melting and ablation fluence thresholds were also predicted, resulting in 0.14 J cm−2 and 0.35 J cm−2, respectively. An ultrafast change in both optical and thermal properties was detected upon laser irradiation. Results also indicate that thermal melting occurs after germanium takes on a metallic character during irradiation, and that the impact ionization process may have a critical role in the laser-induced thermal effect. Therefore, we suggest that the origin of the thermal modification of germanium surface under femtosecond laser irradiation is mostly due the impact ionization process and that its effect becomes more important when increasing the laser fluence.
- Subjects
GERMANIUM films; THIN films; IMPACT ionization; RATE equation model; CARRIER density; PULSED lasers; FEMTOSECOND lasers
- Publication
Nanomaterials (2079-4991), 2022, Vol 12, Issue 21, p3786
- ISSN
2079-4991
- Publication type
Article
- DOI
10.3390/nano12213786