Roughness kinetic and multiaffinity of anisotropic etched silicon

The technique of the anisotropic wet chemical etching had turned into one of the widely used processes for manufacturing the functional materials in microelectromechanical systems. To better understand the issues of growth mechanisms for the characteristic surface morphologies during an anisotropic chemical etching, in this study the formation and evolution of surface structures were investigated by numerical simulation methods. A chemical etching model was established on the basis of chemical reaction and atomic diffusion. Affecting by the anisotropy of the crystalline structure and etching rate, various featured surface morphologies, including the rippling surface, cusp-like hillock, and nano-pyramid, were numerically developed in accordance with the etching conditions. These characteristic structures were also in well agreements with the corresponding experiments. From the theoretical point of view, the surface morphologies were critically influenced by the kinetic factors of the anisotropic etching rate and the atomic diffusion. With the enhancement of theoretical work in the formation mechanism for the anisotropic chemical etching, the practical technique would possess a more competitive advantage for the wide applications in the fields of the functional materials fabrication.

Array structure of monocrystalline silicon surface processed by femtosecond laser machining assisted with anisotropic chemical etching

The procedures for forming elements of sensors of physical quantities by anisotropic etching are examined. How etching conditions influence the roughness of silicon wafers is investigated and ways to decrease the roughness are determined. It is shown that, to etch silicon wafers, the liquid etching procedure is predominantly used. The morphology and roughness of silicon-wafer surfaces are investigated with the help of scanning electron microscopy and atomic-force microscopy.

The relationship the between electrical properties and surface roughness (Ra) of a wet-etched silicon wafer were studied. Ra was measured by an alpha-step process and atomic force microscopy (AFM) while varying the measuring range <TEX>$10{\times}10$</TEX>, <TEX>$40{\times}40$</TEX>, and <TEX>$1000{\times}1000{\mu}m$</TEX>. The resistivity was measured by assessing the surface resistance using a four-point probe method. The relationship between the resistivity and Ra was explained in terms of the surface roughness. The minimum error value between the experimental and theoretical resistivities was 4.23% when the Ra was in a range of <TEX>$10{\times}10{\mu}m$</TEX> according to AFM measurement. The maximum error value was 14.09% when the Ra was in a range of <TEX>$40{\times}40{\mu}m$</TEX> according to AFM measurement. Thus, the resistivity could be estimated when the Ra was in a narrow range.

A comparison of the mechanical behavior of double-layer (TiN/TiC) coatings with a single-layer (TiN andTiC) coatings has been done in this paper. All coatings with the thickness of 2-3 μm were deposited onto H13 hot work tool steel, by the technique of the plasma assisted chemical vapor deposition (PACVD). Compositional and structural properties were investigated by the glancing-angle X-ray diffraction (GIXRD) and the field emission scanning electron microscopy (FESEM). Coating mechanical characterizations were also investigated by the knoop hardness indentation; the pin on disc wear test and the atomic force microscopy (AFM) for assessing the hardness, the wear resistance, the surface topology and roughness variations. Mechanical properties such as the hardness, the wear resistance and the surface roughness were changed when the materail type of layers in coatings was variable. The TiN/TiC coatings showed the maximum microhardness (&gt;27 GPa) and had a better wear resistance than the single-layer coatings. Lower surface roughness was also related to the TiC coating.

Writing FIB implantation and subsequent anisotropic wet chemical etching for fabrication of 3D structures in silicon

Low band-gap energy photocatalytic membrane based on SrTiO3–Cr and PVDF substrate: BSA protein degradation and separation application

The current work introduces a mechanical indentation method to develop and characterize the pyramid-shaped micro-texturing in a square array on biomedical grade SS 316L. The surface morphology, topography, and roughness profiles of the pyramid-shaped micro-textured surfaces are characterized using a field emission scanning electron microscopy, three-dimensional (3D) optical profilometer, and atomic force microscopic (AFM) analysis. The field emission scanning electron microscopy results showed that micro-textures are formed in a periodic manner at different center distances within 2% of error. The AFM 3D image shows the bulging effect near the corners of the pyramid textures due to the application of applied load. Further, the Sa values of the textured samples are found as 1.223, 0.52, and 0.271 µm for the center distance of 150, 250, and 350 µm, respectively, and come under the micro-roughness (Sa &gt; 1–10 µm) and nano-roughness (Sa &lt; 1 µm) scale range. Further, the surface functionality was analyzed in terms of Young's contact angle. The textured surface presents hydrophilic wetting behavior with a contact angle of 42.8°, compared to the untextured part (97.4°) for deionized water. Moreover, with PBS, the textured sample show presents a minimum contact angle, that is, 22.7°, compared to the untextured part (81.1°), which presents a high affinity for simulated body fluid. The results indicate that an increase in surface roughness makes the hydrophilic surface more hydrophilic, supporting the Wenzel statement. Therefore, the mechanical indentation technique can be a promising method for fabricating micro-textured surfaces for implant materials.

The demand for wood in construction has led to shortages of strong wood types, causing a shift to costlier alternatives like concrete and nonbiodegradable materials, prompting the investigation of modifying softwoods for better engineering properties. This study investigates the optimization of a multistep impregnation process utilizing functionalized cellulose nanocrystals (f-CNCs) to enhance softwood properties. The process involves alkali delignification, ultrasonication, and vacuum pressure treatment to improve wood porosity and in turn improve CNC impregnation with uniform dispersion. Microstructural analyses through field emission scanning electron microscopy and atomic force microscopy (AFM) offer detailed insights into cell wall morphology and surface topography, whereas Fourier transform infrared spectroscopy highlights compositional shifts resulting from f-CNC impregnation. Mechanical testing demonstrates significant improvements for treated woods, particularly a 67 percent increase in modulus of elasticity for the 2 percent CNC-treated group compared with the control group; a 71 percent increase in modulus of rupture was observed for 2 percent CNC-, 3 percent NaOH-, and 2 percent acetic acid-treated group compared with the control sample. The sample delignified with 3 percent NaOH and impregnated by 2 percent f-CNC emerged as particularly effective. This research sets the stage for potential advancements in strengthening softwood using CNC, including a novel AFM method and alternative impregnation techniques like the Lowry method, inviting further exploration.

Spectroscopic ellipsometry: A sensitive tool to monitor domains formation during the bias enhanced nucleation of heteroepitaxial diamond

A novel method of fabricating a nano-imprinting mold for a single-electron device is newly proposed, which makes use of the peculiarity of anisotropic wet chemical etching. A row of resist patterns for quantum dots is placed to keep an offset angle θ against a <110> crystalline axis on a (100) Si surface. By an anisotropic wet chemical etching, the Si substrate is diagonally etched along the <110> and <110> directions, and an inverted pyramidal hole with a (111) plane surface is formed. The gap between them becomes narrower than that of the original pattern. Using this method, the nano-imprinting mold for a quantum dot array with narrow gaps beyond the resolution limit of conventional lithography is obtained.

The photostabilization of poly (vinyl chloride) (PVC) film filled with an organotin complex in its structure was examined and compared with the blank PVC film. The organotin (IV) complex that contains 4-(benzylideneamino) benzenesulfonamide as a ligand was synthesized and applied as a PVC photostabilizer. The impact of the complex on the polymer was assessed by comparing the properties of the films with and without the complex, before and after irradiation, using Fourier transform infrared spectroscopy, weight loss, viscosity change, atomic force microscopy, and field emission scanning electron microscopy (FE-SEM). Results showed that the complex film had lower weight loss, gel content, and molecular weight deterioration than the plain PVC film. Also, surfaces of the complexes-filled films were smoother, less lumpy, and more homogeneous. These findings were obtained via the FE-SEM and light microscope images and confirmed by measuring the roughness factor. The organotin (IV) complex proved its activity in delaying the photo-degradation of PVC by several mechanisms. Ultimately, the Tin complex has effectively protected the PVC film against irradiation.&#x0D; The photostabilization of poly (vinyl chloride) (PVC) film filled with an organotin complex in its structure was examined and compared with the blank PVC film. The organotin (IV) complex that contains 4-(benzylideneamino) benzenesulfonamide as a ligand was synthesized and applied as a PVC photostabilizer. The impact of the complex on the polymer was assessed by comparing the properties of the films with and without the complex, before and after irradiation, using Fourier transform infrared spectroscopy, weight loss, viscosity change, atomic force microscopy, and field emission scanning electron microscopy (FE-SEM). Results showed that the complex film had lower weight loss, gel content, and molecular weight deterioration than the plain PVC film. Also, surfaces of the complexes-filled films were smoother, less lumpy, and more homogeneous. These findings were obtained via the FE-SEM and light microscope images and confirmed by measuring the roughness factor. The organotin (IV) complex proved its activity in delaying the photo-degradation of PVC by several mechanisms. Ultimately, the Tin complex has effectively protected the PVC film against irradiation.

A folding rearrangeable nonblocking 4×4 optical matrix switch was designed and fabricated on silicon-on-insulator wafer. To compress chip size, switch elements (SEs) were interconnected by total internal reflection (TIR) mirrors instead of conventional S-bends. For obtaining smooth interfaces, potassium hydroxide anisotropic chemical etching of silicon was utilized to make the matrix switch for the first time. The device has a compact size of 20×1.6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a fast response of 7.5 μs. The power consumption of each 2×2 SE and the average excess loss per mirror were 145 mW and -1.1 dB, respectively. Low path dependence of /spl plusmn/0.7 dB in total excess loss was obtained because of the symmetry of propagation paths in this novel matrix switch.

The undercutting process of thermal SiO2 microcantilevers with different orientations on (100) Si wafer was studied. The silicon substrate was removed by anisotropic chemical etching with a 25 wt. % aqueous solution of TMAH or a 30 wt. % aqueous KOH solution at 80 ?C. It was found that [110] oriented cantilevers were undercutting frontally along the length and [100] oriented cantilevers experience undercutting along the width of the cantilever, which is a less time consuming process. The studies showed that the [100] orientation of SiO2 microbridges enables theirs fabrication on a (100) oriented Si substrate.

Introduction: Laser irradiation of dentin surface can affect its surface topography and roughness. Atomic force microscopy (AFM) is among the most efficient tools for determination of surface topography of natural biomolecules in nano-scales. Surface roughness affects plaque retention especially in the cervical region. This study aimed to assess and compare the obstruction of dentinal tubules and dentin surface roughness after irradiation of erbium: yttrium aluminum garnet (Er:YAG ) and CO2 lasers for treatment of dentin hypersensitivity (DH). Methods: Five disc-shaped samples measuring 3 mm in thickness were fabricated by horizontal sectioning of the cervical area of five extracted human molars using a low speed saw. Each disc was divided into 3 segments by a bur under water coolant. The three segments of each disc were placed on a glass slide. First segment: No intervention (control group). Second segment: Er:YAG laser irradiation (2940 nm, 50 mJ, 10 Hz and 0.5 W, 30 seconds) along with water coolant. Third segment: CO2 laser irradiation (10600 nm, 80 Hz, 0.3 W, 30 seconds) along with water coolant. After that, the surfaces underwent non-contact AFM. The diameters of dentinal tubules as well as surface roughness were then measured and statistically analyzed using repeated measures ANOVA. Results: The surface roughness parameters (Ra, Rq) showed increased roughness after laser irradiation and this increase in roughness after Er:YAG laser application was significant compared to the control group (P=0.048). However, CO2 laser caused no significant change in surface roughness. Also, after Er:YAG laser application, fewer open dentinal tubules were observed and the remaining open tubules had a smaller diameter. Conclusion: Based on the results, Er:YAG laser irradiation obstructs the dentinal tubules and increases the dentin surface roughness. This increase in surface roughness can cause microbial plaque retention and increase the risk of caries and periodontal disease. Application of CO2 laser (compared to Er:YAG) lead to slight but clinically significant obstruction of dentinal tubules and surface roughness.