AI Article Synopsis
- - The study examines how a germanium thin film reacts to ultra-short laser pulses, focusing on changes in electron and lattice temperatures, and optical properties like dielectric function and reflectivity using a two-temperature model and the Drude model.
- - Researchers calculated melting and ablation thresholds for germanium, finding values of 0.14 J/cm² and 0.35 J/cm² respectively, and observed rapid changes in optical and thermal properties during laser exposure.
- - The findings suggest that thermal melting in germanium occurs after it behaves like a metal under laser irradiation, highlighting the significance of the impact ionization process, which increases in importance as laser power intensifies.
Article 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 and 0.35 J cm, 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.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9657278 | PMC |
| http://dx.doi.org/10.3390/nano12213786 | DOI Listing |
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