Large-Scale Laser Fabrication of Antifouling Silicon-Surface Nanosheet Arrays via Nanoplasmonic Ablative Self-Organization in Liquid CS₂ Tracked by a Sulfur Dopant

Abstract

Large-scale surface nanopatterning of a commercial silicon (Si) wafer in the form of regular 1D arrays of high-aspect-ratio vertical nanosheets (NSs) for antifouling and other potential promising optoelectronic, nanophotonic, and sensing applications was performed via multishot picosecond IRlaser ablation under a 5-mm-thick carbon disulfide liquid layer. Specifically, the nanopatterned surface layer demonstrates the broad ultralow mid-IR transmittance and the high content of sulfur, carbon, and even oxygen in the modified submicron-thick top layer, preventing the appearance of a Staphylococcus aureus bacterial biofilm. High-resolution transmission electron microscopy studies exhibit the anticorrelating inner versus outer surface abundance of donor sulfur versus adverse carbon and oxygen components and the amorphous structure of the sulfur-hyperdoped NSs atop their crystalline basements. These NSs indicate their appearance via the interfacial vapor/ plume bubble-mediated codeposition of Si ablation nanoplumes from the regular trenches and sulfur-containing products of carbon disulfide decomposition in the bubble. Numerical modeling indicates the nanoplasmonic origin of the Si NSs, self-limited in both the 100 nm periods and the submicron heights.

Multifunctional Sulfur‐Hyperdoped Silicon Nanoparticles with Engineered Mid‐Infrared Sulfur‐Impurity and Free‐Carrier Absorption

“…Production of hyperdoped Si nanoparticles in colloidal solutions was performed during ablative laser nanopatterning of Si surfaces in carbon disulfide ambient, [ 20 ] in one pass over 10 mm × 10 mm wide areas on a 0.38‐mm thick phosphor‐doped commercial Si(111) wafer (specific resistivity of 4.5 Ω cm) inside a glass beaker with a top 5‐mm thick carbon disulfide (CS 2 ) layer; the ppb‐level phosphor impurity hadn't affected the studies.…”

“…The laser exposure was provided at 100‐kHz repetition rate by 300‐fs, IR‐laser pulses focused onto the sample surface into a spot with the 1/e‐radius σ ≈ 15 µm (the peak surface laser fluence F 0 ≈ 0.5 J cm −2 ) with 400 pulses per spot, resulting in visibly black, highly‐ordered nanosheet‐like surface textures (Figures 1a and 2a) described elsewhere. [ 20 ]…”

“…Laser production of hyperdoped Si nanoparticles in the form of colloidal solutions was performed via the experimental approach, previously used for ablative laser nanopatterning of Si surfaces in liquid carbon disulfide (CS 2 ) ambient. [ 20 ] Laser processing was done in one pass over a 0.38‐mm thick phosphor‐doped commercial Si(111) wafer under a CS 2 layer inside a glass beaker by 300‐fs, IR‐laser (λ ≈1030 nm) pulses, resulting through a multi‐step process described in Figure , in visibly black, highly‐ordered nanosheet‐like surface textures ( Figure a). [ 20 ] The produced yellowish colloidal solutions were deposited onto similar Si wafer substrates for structural and chemical characterization, or separated by centrifugation, dissolved in isopropyl alcohol and deposited as a 0.2‐µm thick layer onto the fluorite (CaF 2 ) substrates for the IR spectral characterization and RF heating.…”

“…[ 35 ] In the hybrid Si NPs, pure elemental sulfur could reside on nanograin boundaries and within the resolidified amorphous material, with the bulk (precipitated, S 0 , S n 2− ) form ≈10% of the overall sulfur content. This is much lower, than the 35% precipitated atomic fraction of the overall sulfur content in the parent Si nanopatterns, [ 20 ] apparently, because of the highly‐dispersed structure of the Si NPs. This estimate of precipitated sulfur concentration in the Si NPs indicates that its atomic concentration, available for optoelectronic applications as broadband [ 1,10–14 ] or selective band‐engineered [ 15,16 ] IR‐absorption in S‐donor bands in silicon and the resulting IR‐photoconductivity, could be as high as ≈10 20 S‐atoms cm −3 .…”

Nanoreinforcements of Two-Dimensional Nanomaterials for Flame Retardant Polymeric Composites: An Overview

“…It is believed that the biggest obstacle to the application of two-dimensional nanomaterials as ame retardant additives is the high cost and the low yield of the peeled sheet structures [46]. Recently, as the number of publications related to these emerging twodimensional nanomaterials has increased dramatically, a large number of studies on the large-scale production of twodimensional nanosheets have paved the way for ame-retardant applications [47,48]. Yao et al [49] reported a facile and scalable method for the preparation of monolayer and fewlayer of BN, MoS 2 , and graphene using a combination of low-energy ball milling and sonication.…”