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Raman spectra of BDD before and after fs-laser treatment (23 J/cm², 1000 pulses), red and blue lines, respectively. In the inset, it is noticeable the left shift of 1330 cm⁻¹ diamond peak, pointing out a slight lattice stress.
Source publication
We demonstrate the formation of laser-induced periodic surface structures (LIPSS) in boron-doped diamond (BDD) by irradiation with femtosecond near-IR laser pulses. The results show that the obtained LIPSS are perpendicular to the laser polarization, and the ripple periodicity is on the order of half of the irradiation wavelength. The surface struc...
Citations
... LIPSSs have also been shown to be related to the catalytic activity in electrochemical processes. For example, Granados et al. [90] showed a large-area LIPSS perpendicular to the laser polarization direction prepared on BDD by NIR ultrafast laser pulses, as shown in Figure 7(b). Through water drop experiments, it was demonstrated that LIPSS structures improve the wettability of BDD electrodes, which can be used for the electrochemical oxidation of organics or water treatment. ...
... Color online) (a) Large-area homogeneous LIPSS structures prepared by adjusting laser parameters increase optical transmittance in the NIR band[88]; Copyright©2018, Springer. (b) Water droplet experiments demonstrate homogeneous LIPSS structures on BDD and improve surface wettability[90]. Copyright©2017, OSA. ...
Hard and brittle materials have high hardness, excellent optical stability, chemical stability, and high thermal stability. Hence, they have huge application potential in various fields, such as optical components, substrate materials, and quantum information, especially under harsh conditions, such as high temperatures and high pressures. Femtosecond laser direct writing technology has greatly promoted the development of femtosecond laser-induced periodic surface structure (Fs-LIPSS or LIPSS by a femtosecond laser) applications of hard and brittle materials due to its high precision, controllability, and three-dimensional processing ability. Thus far, LIPSSs have been widely used in material surface treatment, optoelectronic devices, and micro-mechanics. However, a consensus has not been reached regarding the formation mechanism of LIPSSs on hard and brittle materials. In this paper, three widely accepted LIPSS formation mechanisms are introduced, and the characteristics and applications of LIPSSs on diamonds, silicon, silicon carbide, and fused silica surfaces in recent years are summarized. In addition, the application prospects and challenges of LIPSSs on hard and brittle materials by a femtosecond laser are discussed.
... This strategy has already shown promising results regarding the fabrication of effective diamond metasurfaces [13]. In fact, the production of LIPSS-based nanostructures in diamond and the study of its photonic properties is an emerging field of research [13,14,[25][26][27]. One of the challenges here resides in the difficulty of producing reliably the required aspect ratio to behave as effective AR coatings [28]. ...
We study the propagation of coherent broadband light through laser induced periodic surface structures (LIPSS) fabricated on diamond surfaces. 3D finite-difference time-domain (FDTD) simulations were carried out for a variety of experimentally produced LIPSS morphologies, which include the specific nanometer-scale mesoscopic irregularities arising from the fabrication technique. We compare their performance with sinusoidal grating-like structures, showing that the specific features present in LIPSS nanoripples produce a considerable scattering and diffraction when compared to the ideal nanostructures. With a view on determining the scope of the potential optical and photonic applications of LIPSS, we evaluate the effect of these irregularities on the transmitted spatial beam quality and the spatial phase characteristics of the optical wavefront in a broad spectral range.
... Diamond nanostructuring can be useful not only for solar applications, but also for other kinds of devices. In 2017, Granados et al. [70] reported the capability of Boron-Doped Diamond (BDD) to become highly hydrophilic after nanostructuring its surface, whereas Sartori et al. [71] demonstrated that surface nano-patterning is a cleanroom-free and flexible processing technique for adjusting the electro-chemical properties of BDD. Both works aimed at developing electrodes for (bio)sensing, catalysis or energy storage. ...
... On this basis, it has been shown how the nonlinear multiphotonic excitation processes of carriers from the valence band to the conduction band of these materials (e.g., diamond) can provide structural and electronic structural changes, which can also result in electronic and compositional variations that can strongly affect the materials' properties at their surface. It follows that together with the change of material topography ranging from LSFL to HSFL, which can strongly vary the material's wettability [70,83,84] and optical properties [60], even functionalizations can be provided by carefully controlling all materials' surface features as well as the laser beam and all the experimental parameters used (e.g., sample holder scanning speed, number of spatial effective incident pulses, material's roughness and its preparation, laser incidence angle, surrounding environment). Thanks to LIPSS and relative processes, new perspectives in the fields of application of WBS and dielectrics can be added, such as, for instance, diamond for solar energy conversion [60], THz optical components [72] or new optoelectronic devices driven by intermediate band formation within the material's bandgap, doping in the vicinity of surface defects or the assembling of new nanotemplate systems. ...
With the aim of presenting the processes governing the Laser-Induced Periodic Surface Structures (LIPSS), its main theoretical models have been reported. More emphasis is given to those suitable for clarifying the experimental structures observed on the surface of wide bandgap semiconductors (WBS) and dielectric materials. The role played by radiation surface electromagnetic waves as well as Surface Plasmon Polaritons in determining both Low and High Spatial Frequency LIPSS is briefly discussed, together with some experimental evidence. Non-conventional techniques for LIPSS formation are concisely introduced to point out the high technical possibility of enhancing the homogeneity of surface structures as well as tuning the electronic properties driven by point defects induced in WBS. Among these, double- or multiple-fs-pulse irradiations are shown to be suitable for providing further insight into the LIPSS process together with fine control on the formed surface structures. Modifications occurring by LIPSS on surfaces of WBS and dielectrics display high potentialities for their cross-cutting technological features and wide applications in which the main surface and electronic properties can be engineered. By these assessments, the employment of such nanostructured materials in innovative devices could be envisaged.
... For instance, the laser induced periodic surface structure (LIPSS) technique has been used in the fields of tribology, wettability analysis, and mechanics because it allows one to vary the polarization of the laser and its scan speed, pulse energy, and pulse number. This technology would allow for the fabrication of LIPSS suitable for use in various applications [27][28][29]. In addition, micro/nanostructures are used widely for numerous purposes in the field of optics. ...
Femtosecond laser processing is fast becoming a pervasive method for fabricating micro/nanostructures because it can be used to produce micro/nanostructures on myriads of materials with high precision and resolution, requires little control over environmental conditions, and is simple to implement. Here, we review recent developments in the use of femtosecond lasers for the fabrication of micro/nanostructures through ablation and two-photon polymerization (TPP). Moreover, the applications of some of the fabricated micro/nanostructures are also discussed. We highlight the advantages of femtosecond laser processing by explaining the underlying principles of laser ablation and TPP. We also show the use of this method to fabricate new devices with outstanding performance in several application realm, such as sensors, optical devices, microfluidic chips, and soft robotics.
... They found that the hydrophilicity of the original surface was enhanced by the groove pattern and weakened by the dimple pattern. Granados et al. [13] demonstrated that the formation of laser-induced periodic surface structures (LIPSS) in boron-doped diamond by irradiation with femtosecond laser leads to hydrophilic behavior. Superhydrophilicity can also be achieved on stainless steel by LIPSS formation, and θ increases with the laser scanning speed [14]. ...
A general machine learning (ML) framework of surface wetting is proposed by considering a broad range of factors, including solid surface topography, solid surface chemistry, liquid properties, and environmental conditions. In particular, an XGBoost-based ML model is demonstrated for learning the surface wetting behaviors processed by a laser-based surface functionalization process, namely nanosecond laser-based high-throughput surface nanostructuring (nHSN). This is the first known attempt to apply machine learning to surface wetting by considering both surface topography and surface chemistry properties. Novel microscale and nanoscale topography parameters viz., roughness, fractal, entropy, feature periodicity are defined with suitable computer algorithms to comprehensively describe the surface topography. A novel set of surface chemistry parameters such as polarity, volume, and amount of functional groups are also used as the machine learning model input. Upon analyzing the importance of each parameter for the nHSN process, surface chemistry shows the greatest importance in determination of surface wettability, while surface morphology also plays a part in influencing the wettability.
... The influence of oxygen partial pressure during film deposition on the film structure was investigated by X-ray diffraction (XRD) measurements (Siemens D5000 diffractometer with Cu Kα radiation and a detector scan with an incidence angle of 1°) [17] . These investigations revealed a strong dependence of the appearance of the TiO 2 phase on oxygen partial pressure. ...
Laser induced periodic surface structures (LIPSS) represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography. This method is much simpler and cost effective. In this work, LIPSS on Si surfaces were generated using femtosecond laser pulses of 800 nm wavelength. Photocatalytic substrates were prepared by depositing TiO 2 thin films on top of the structured and unstructured Si wafer. The coatings were produced by sputtering from a Ti target in two different types of oxygen atmospheres. In first case, the oxygen pressure within the sputtering chamber was chosen to be high (3 × 10 –2 mbar) whereas it was one order of magnitude lower in second case (2.1 × 10 –3 mbar). In photocatalytic dye decomposition study of Methylene blue dye it was found that in the presence of LIPSS the activity can be enhanced by 2.1 and 3.3 times with high pressure and low pressure grown TiO 2 thin films, respectively. The increase in photocatalytic activity is attributed to the enlargement of effective surface area. In comparative study, the dye decomposition rates of TiO 2 thin films grown on LIPSS are found to be much higher than the value for standard reference thin film material Pilkington Activ TM .
... 11,15,37−39 In this context, the large variety of influencing laser parameters (e.g., laser peak fluence F, pulse duration τ, and number of laser pulses N) facilitates the adjustment of the LIPSS morphology and thus the tailoring of the surface properties. 11,19,21,31,32,40 For the wettability of homogeneous material surfaces, it was shown that LIPSS-based surface structuring is a versatile tool to achieve hydrophobic 41,42 or hydrophilic 15,38 properties. In the present work, the selective generation of LIPSS is studied on a metal/semiconductor alloy that consists of a silver (Ag) and silicon (Si) phase (hereinafter referred to as the Ag−Si alloy) for the very first time to the best of our knowledge. ...
Femtosecond (fs) laser-induced periodic surface structures (LIPSS) were selectively generated on the surface of an Ag-Si alloy consisting of a metallic and a semiconducting phase. For this purpose, the alloy was irradiated with linearly polarized fs-laser pulses (τ = 300 fs, λ = 1025 nm, frep = 100 kHz) using a laser peak fluence F = 0.30 J/cm². Due to the different light absorption behavior of the semiconductor (Si) and the metal (Ag) phase that results in different ablation thresholds of the respective phase, pronounced LIPSS with a period of Λ ≈ 950 nm and a modulation depth of h ≈ 220 nm were generated solely on the Si phase. The alloy surface was characterized by scanning electron microscopy, optical microscopy, white light interference microscopy and atomic force microscopy before and after laser irradiation. Chemical analysis was carried out by energy dispersive X-ray spectroscopy, revealing surface oxidation of the Si phase and no laser-induced chemical modification of the Ag phase. The surface wettability of the alloy was evaluated with distilled water and compared to the single constituents of the composites. After fs-laser irradiation, the surface is characterized by a reduced hydrophilic water contact angle. Furthermore, the alloy selectively structured with LIPSS revealed a droplet shape change due to the distinctly different contact angles on the Si (θ = 5°) and the Ag (θ = 74°) phase. This phenomenon was evaluated and discussed by local contact angle analyses using a confocal laser scanning microscope and a Rhodamine B dye. In addition, it was shown that the shape change due to different contact angles of the components allowed a targeted droplet movement on a macroscopic material boundary (Ag/Si) of the alloy. Selectively structured metal/semiconductor surfaces might be of particular interest for microfluidic devices with a directional droplet movement and for fundamental research of wettability.
... Whereby the surface of the material is ablated using Nano-, pico-, or femtosecond pulsed lasers so as to generate specific surface textures to achieve desirable optical, electrical or mechanical characteristics. Recent studies have shown the potential of this technique to improve the wettability of ceramic [17] as well as metallic materials [18]. Zhang et al. used this technique to improve wettability characteristics (and in turn the joint strength) of Al2O3 surface for brazing with stainless steel under vacuum [19]. ...
The effect of micro patterning of cemented carbide surface using nanosecond diode pumped solid-state pulsed laser on the strength of induction brazed carbide and steel joints has been investigated. Surface patterns increase the total surface area of the joint and, for an originally hydrophilic surface, increase the wettability of a liquid on a solid surface such that, instead of building droplets, the liquid spreads and flows on the surface. Microcomputed tomography (µ-CT) was used to observe the filler/carbide interface after brazing and to analyze the presence of porosity or remnant flux in the joint. Microstructures of the brazed joints with various surface patterns were analyzed using scanning electron microscopy. The strength of the joints was measured using shear tests. Results have shown that the groove pattern on the surface of carbide increases the joint strength by 70–80%, whereas, surface patterns of bi-directional grooves (grid) reduced the joint strength drastically. Dimples on the carbide surface did not show any improvement in the strength of the brazed joints compared to samples with no surface pattern.
... Diamond is a material with desirable mechanical and chemical properties for biomimetic structures [1][2][3], (bio)electrochemistry [4], imprint lithography [5] and other applications, due to its high Young's modulus (up to~10 6 N mm −2 ), high thermal conductivity (> 2000 W m −1 K −1 ) [4], low thermal expansion coefficient (10 −6 K −1 at 300 K) [6], low coefficient of friction [7], non-toxicity, and versatile surface chemistry. Many of those applications require patterning of the diamond surface into regular functional structures, such as nanowires [8,9], micro/nanopillars, microchannels [10] and pads [11], which are normally achieved by multistep lithography (photo-, e-beam, focused ion beam) and/or etching processes [12,13]. ...
Micro-patterned diamond has been investigated for numerous applications, such as biomimetic surfaces, electrodes for cell stimulation and energy storage, photonic structures, imprint lithography, and others. Controlled patterning of diamond substrates and moulds typically requires lithography-based top-down processing, which is costly and complex. In this work, we introduce an alternative, cleanroom-free approach consisting of the bottom-up growth of nanocrystalline diamond (NCD) micropillar arrays by chemical vapour deposition (CVD) using a commercial porous Si membrane as a template. Conformal pillars of ~4.7 μm in height and ~2.2 μm in width were achieved after a maximum growth time of 9 h by hot-filament CVD (2% CH 4 in H 2 , 725 °C at 10 mbar). In order to demonstrate one of many possible applications, micropillar arrays grown for 6 h, with ~2 μm in height, were evaluated as moulds for imprint lithography by replication onto hard cyclic olefin copolymer (COC) and onto soft polydimethylsiloxane (PDMS) elastomer. The results showed preserved mechanical integrity of the diamond moulds after replication, as well as full pattern transfer onto the two polymers, with matching dimensions between the grown pillars and the replicated holes. Prior surface treatment of the diamond mould was not required for releasing the PDMS replica, whereas the functionalisation of the diamond surface with a perfluorododecyltrichlorosilane (FDDTS) anti-stiction layer was necessary for the successful release of the COC replica from the mould. In summary, this paper presents an alternative and facile route for the fabrication of diamond micropillar arrays and functional micro-textured surfaces.
... Femtosecond (fs) laser ablation is a powerful tool to fabricate microstructures and nanostructures for biomedical, 32−34 wettability, 35 and photonics applications. 36 Focusing an ultrafast laser beam at the liquid/material interface helps to engineer the desired nanomaterials with required shapes, as a function of the influence of liquid parameters (viscosity, polarity, etc.), laser fluence, and pulse number. ...
Fabrication of reproducible and versatile surface enhanced Raman scattering (SERS) substrates is crucial for real time applications such as explosive detection for human safety and biological imaging for cancer diagnosis. However, it still remains a challenging task even after several methodologies were developed by various research groups primarily due to (a) lack of consistency in detection of a variety of molecules (b) cost-effectiveness of the SERS substrates prepared and (c) byzantine preparation procedures etc.. Herein, we establish a procedure for preparing reproducible SERS active substrates comprised of laser-induced nanoparticle embedded periodic surface structures (LINEPSS) and metallization of Silicon (Si) LINEPSS. LINEPSS were fabricated using the technique of femtosecond laser ablation of Si in acetone. The versatile SERS active substrates were then achieved by two ways including drop casting of silver (Ag)/gold (Au) nanoparticles (NPs) on Si LINEPSS and Ag plating on the Si LINEPSS structures. By controlling the LINEPSS grating period, the effect of plasmonic nanoparticles/plasmonic plating on the Si NPs embedded periodic surface structures enormously improved the SPR strength, resulting in the consistent and superior Raman enhancements. The reproducible SERS signals were achieved by detecting the molecules of methylene blue (MB), 2, 4-Dinitrotoluene (DNT) and 5-amino-3-nitro-l,2,4-triazole (ANTA). The SERS signal strength is determined by the grating period which in turn is determined by the input laser fluence. The SERS active platform with grating periods of 130±10 nm and 150±5 nm exhibited strong Raman enhancements of ~10^8 for MB and ~10^7 for ANTA molecules, respectively, and these platforms are demonstrated to be capable even for multiple usages.
