Direct laser writing of amorphous silicon on Si-substrate induced by high repetition femtosecond pulses

Abstract

This research aimed to study the effects of laser parameters on direct silicon amorphorization. It was found that higher repetition rate of laser pulses gives smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model is developed for the calculation of the average surface temperature after n-pulses; it was found that for a constant power and a constant repetition rate, an increase in the pulse number does not correspond to a significant increase in the surface temperature. Moreover, at the controlled laser power level, the surface temperature will not exceed the melting point of silicon. Therefore, thermal induced damage is not observed during the amorphization.

Fabrication of amorphous micro-ring arrays in crystalline silicon using ultrashort laser pulses

“…Recently, direct writing of crystalline lines in hydrogenated amorphous Si films was reported, which can be considered as semiconductive channels in an insulating matrix, due to the enormous difference in electrical conductivity of both phases 15 . The inverse process, direct laser writing of amorphous structures in crystalline Si by high repetition rate femtosecond laser irradiation was reported by Kiani et al 16,17 . Using nanosecond laser irradiation, Pena et al produced micrometer-sized amorphous humps with a height of a few nanometers 18 .…”

High Intensity Laser Induced Reverse Transfer: Solution for Enhancement of Biocompatibility of Transparent Biomaterials

“…In samples that were immersed in SBF solution for 4 days according to the previous reported results for similar structures [9,12] there are primary peaks related to hydroxyapatite-like composition, which can be the result of a good amount of NFTi on the samples and proper places for calcium and phosphorous to grow on, as shown in Figure 10. The hydroxyapatite and other calcium to phosphorus composition peaks relating to Raman and XRD patterns of samples which were produced by higher powers have higher intensities compared to the samples produced by a laser power of 5 W. This can also be due to little or no generation of NFTi on the specimens produced by a laser power of 5 W, and less suitable places where calcium and phosphorous elements can start nucleating and growing [20,21]. The XRD and Raman results in Figure 9 show that titanium and titanium oxide phases reflected severe peaks on samples created by laser powers of 5, 9 and 12 W. Generally, increasing laser power results in injecting pulses with higher intensity on the center of the ablation, which leads to a rise in the plume temperature and consequently more particle ablation and fiber generation.…”

Defective Solid-Phase Epitaxial Growth of Si

“…Additionally, while SPEG was previously reported for cases where the α-Si layer was produced via deposition or laser annealing Figure 1 The macroscopic SPEG process: (A) a virgin (hkl) Si wafer, (B) amorphization of the near-surface region of the wafer via ion implantation, (C) partial crystallization of the α-Si layer via annealing to effect epitaxial growth at the amorphous/crystalline interface, and (D) completed crystallization of the entire α-Si layer resulting in a single-crystal film with same orientation at the substrate. (Bonse et al, 2004;Costache et al, 2004;Izawa et al, 2007;Jia et al, 2004;Kiani et al, 2009Kiani et al, , 2010, SPEG where ion implantation is used to produce the α-Si layer is of the most technological relevance and will be addressed here exclusively.…”