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20 September 2004 Femtosecond laser-induced nanostructuring and phase transformation of crystalline silicon
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Proceedings Volume 5448, High-Power Laser Ablation V; (2004)
Event: High-Power Laser Ablation, 2004, Taos, New Mexico, United States
Surface morphology and structural changes upon femtosecond laser ablation from crystalline silicon (001) were examined ex-situ by optical, scanning electron, and atomic force microscopy, as well as Raman spectroscopy. After repetitive illumination with several thousand laser pulses at an intensities below or near the single shot damage threshold (2x1012 W/cm2), self-assembled periodic nanostructures with periods of 200 nm resp. 600-700 nm develop at the crater bottom. Micro-Raman spectroscopy reveals phase transformations inside the crater from Si-I to the polymorphs Si-III, Si-XII, hexagonal Si-wurtzite (Si-IV), and amorphous silicon, pointing to substantial pressure and volume changes during the interaction. The ablation dynamics was monitored by time-of-flight mass spectroscopy, showing the emission of superthermal positive ions with a kinetic energy of several eV as well as significant contributions at lower kinetic energies. The results suggest that the ablation is associated with considerable recoil pressure and leaves behind a severely perturbed crystal surface. The resulting instability relaxes by a self-organization, independent of the initial, and surrounding, crystal structure.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Juergen Reif, Florenta Costache, and Simona Kouteva-Arguirova "Femtosecond laser-induced nanostructuring and phase transformation of crystalline silicon", Proc. SPIE 5448, High-Power Laser Ablation V, (20 September 2004);

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