High spatial frequency laser induced periodic surface structure formation in germanium by mid-IR femtosecond pulses
| Autor: | Austin, Drake. R., Kafka, Kyle R. P., Lai, Yu Hang, Wang, Zhou, Zhang, Kaikai, Li, Hui, Blaga, Cosmin I., Yi, Allen Y., DiMauro, Louis F., Chowdhury, Enam A. |
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| Rok vydání: | 2016 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1063/1.4964737 |
| Popis: | Formation of high spatial frequency laser induced periodic surface structures (HSFL) in germanium by femtosecond mid-IR pulses with wavelengths between $\lambda=2.0$ and $3.6 \; \mathrm{\mu m}$ was studied with varying angle of incidence and polarization. The period of these structures varied from $\lambda/3$ to $\lambda/8$. A modified surface-scattering model including Drude excitation and the optical Kerr effect explains spatial period scaling of HSFL across the mid-IR wavelengths. Transmission electron microscopy (TEM) shows the presence of a $30 \; \mathrm{n m}$ amorphous layer above the structure of crystalline germanium. Various mechanisms including two photon absorption and defect-induced amorphization are discussed as probable causes for the formation of this layer. Comment: 7 pages total (1 page of supplementary material) |
| Databáze: | arXiv |
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