Investigating Laser-Induced Periodic Surface Structures (LIPSS) Formation in Silicon and Their Impact on Surface-Enhanced Raman Spectroscopy (SERS)

Abstract

Laser-induced periodic surface structures (LIPSS) have gained significant attention due to their ability to modify the surface morphology of materials at the micro-nanoscale and show great promise for surface functionalization applications. In this study, we specifically investigate the formation of LIPSS in silicon substrates and explore their impact on surface-enhanced Raman spectroscopy (SERS) applications. This study reveals a stepwise progression of LIPSS formation in silicon, involving three distinct stages of LIPSS: (1) integrated low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL), (2) principally LSFL and, (3) LSFL at the edge of the irradiated spot, elucidating the complex interplay between laser fluence, pulse number, and resulting surface morphology. Furthermore, from an application standpoint, these high-quality multi-scale periodic patterns lead to the next step of texturing the entire silicon surface with homogeneous LIPSS for SERS application. The potential of LIPSS-fabricated silicon substrates for enhancing SERS performance is investigated using thiophenol as a test molecule. The results indicate that the Au-coated combination of LSFL and HSFL substrates showcased the highest enhancement factor (EF) of 1.38×106. This pronounced enhancement is attributed to the synergistic effects of localized surface plasmon resonance (LSPR) and surface plasmon polaritons (SPPs), intricately linked to HSFL and LSFL characteristics. These findings contribute to our understanding of LIPSS formation in silicon and their applications in surface functionalization and SERS, paving the way for sensing platforms.

Reversible Laser Imprinting of Phase Change Photonic Structures in Integrated Waveguides

“…The formation of laser-induced periodic surface structures is a well-known phenomenon that is observed for virtually all solid materials exposed to short laser pulses of high energy, although the complexity of the involved processes still precludes its full understanding. , Despite that, the possibility of obtaining subwavelength (and even deeply subwavelength) LIPSS drives the research for their applications, particularly in the field of photonics, e.g., for polarization conversion, as a basis for sensing platforms , and distributed feedback laser resonators . Very recently, a formation of unique class of phase change LIPSS was demonstrated in films of chalcogenide PCMs. ,,, As opposed to “conventional” LIPSS that are formed due to material reorganization or removal, LIPSS in PCM exhibit spatially modulated phase transition and thus imply the possibility of reversible control.…”

Study for Photo-Induced Enhanced Raman Spectroscopy with Laser-Induced Periodic Surface Structures on Lithium Niobate on Insulator

“…The inherent characteristics of ultrashort pulse duration and ultrahigh energy of a femtosecond (fs) laser can be employed to fabricate micro/nanostructures for SERS substrates, superior to the traditional chemical growth methods in terms of high efficiency, , material flexibility, minimal thermal impact, simplicity of operation without masks, environmental friendliness, and cost savings. − Laser-induced periodic surface structures (LIPSSs), , as one of the most intriguing phenomena induced by fs laser, are extremely favorable for applications of micro-optical elements, nanofluidic channels, optical data storage, etc., owing to their unique properties . Research on SERS based on fs-laser-induced LIPSSs have been preliminary reported, − however, without systematical investigation on their mechanisms and further applications.…”