The generation of nano-patterns on a pure silicon wafer in air and argon with sub-diffraction limit nanosecond laser pulses

Abstract

Intense nanosecond laser pulses were delivered to sub-diffraction limit spots on pure Si wafers with a near field scanning optical microscope (NSOM) for possible nanoscale direct patterning. Compared with the previous results obtained with a femtosecond laser, no evidence of nanoscale laser ablation on Si targets was observed even under the maximum allowable laser energy (i.e. before the damage of NSOM probes). The formation of nano-patterns on pure Si wafers with nanosecond laser pulses, which were in the form of protrusions, can be explained as resulting from the melting and recrystallization along with the oxidation of pure Si targets during and after the laser pulses. Note that these nano-protrusions were primarily composed of SiO2 and nano-crystallized Si (nc-Si).

Analysis of nanopatterning through near field effects with femtosecond and nanosecond lasers on semiconducting and metallic targets

“…Through the additional examination of the protrusions generated with nanosecond laser ͑i.e., through EDS, XRD, and TEM scanning͒, we found that these protrusions are composed with a significant amount of nanocrystalline Si which did not appear in femtosecond results. 17 b. Contribution of number of laser pulses.…”

“…The protrusions can be formed either from nanoscale oxidation 18 or nanoscale melting and recrystallization of the target. 17 The height of protrusion increases slowly with respect to the number of laser pulses due to the increased separation distance between the NSOM probe and the intrinsic target when the protrusions were formed. Nanopattern formation following this trend was observed on targets with high ablation threshold and low oxidation temperature ͑e.g., Si with nanosecond͒.…”

“…However, based on the author's previous experiments, NSOM based nanoscale laser-material interaction is very sensitive to ͑a͒ material composition of the targets and ͑b͒ optical conditions of incident light. [17][18][19] Very tiny or even no nanopatterns can be generated on the targets unless well controlled experimental conditions are maintained. Also, the size and shape ͑e.g., protrusions and craters͒ of nanopatterns change significantly in different experimental conditions.…”

Assembling of Silicon Nanoflowers with Significantly Enhanced Second Harmonic Generation Using Silicon Nanospheres Fabricated by Femtosecond Laser Ablation

“…In the past two decades, much effort has been devoted to the improvement of the optical properties of Si. It has been demonstrated that a significant improvement in emission efficiency can be achieved in porous Si or Si nanocrystals. − Stimulated by this improvement, various chemical − and physical − methods have been proposed to synthesize or fabricate Si nanoparticles (NPs) with diameters ranging from a few to several tens of nanometers. One of the motivations is the use of Si NPs, which is highly biocompatible, as imaging agents in the field of biophotonics.…”

Laser‐Induced Artificial Defects (LIADs): Towards the Control of the Spatiotemporal Dynamics in Spin Transition Materials

“…Movie M3 (Supporting Information) shows the defect ablation and Figure displays the surface topography of a LIAD determined by atomic force microscopy (AFM). The primary advantages of the laser ablation method are the high spatial resolution,14 the fast and simple sample processing (“direct writing”), and low sample contamination. On the other hand, the ablation is always accompanied by the appearance of various defects, local disorder, and stress in the material 15.…”