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The dewetting of thin Pt films on different surfaces is investigated as a means to provide the patterning for the top-down fabrication of GaN nanowire ensembles. The transformation from a thin film to an ensemble of nanoislands upon annealing proceeds in good agreement with the void growth model. With increasing annealing duration, the size and shape uniformity of the nanoislands improves. This improvement speeds up for higher annealing temperature. After an optimum annealing duration, the size uniformity deteriorates due to the coalescence of neighboring islands. By changing the Pt film thickness, the nanoisland diameter and density can be quantitatively controlled in a way predicted by a simple thermodynamic model. We demonstrate the uniformity of the nanoisland ensembles for an area larger than 1 cm2. GaN nanowires are fabricated by a sequence of dry and wet etching steps, and these nanowires inherit the diameters and density of the Pt nanoisland ensemble used as a mask. Our study achieves advancements in size uniformity and range of obtainable diameters compared to previous works. This simple, economical, and scalable approach to the top-down fabrication of nanowires is useful for applications requiring large and uniform nanowire ensembles with controllable dimensions. [ABSTRACT FROM AUTHOR]

The properties of organic heterostructures with mixed layers made of arylenevinylene-based polymer donor and non-fullerene perylene diimide acceptor, deposited using Matrix Assisted Pulsed Laser Evaporation on flat Al and nano-patterned Al electrodes, were investigated. The Al layer electrode deposited on the 2D array of cylindrical nanostructures with a periodicity of 1.1 µm, developed in a polymeric layer using UV-Nanoimprint Lithography, is characterized by an inflorescence-like morphology. The effect of the nanostructuring on the optical and electrical properties was studied by comparison with those of the heterostructures based on a mixed layer with fullerene derivative acceptor. The low roughness of the mixed layer deposited on flat Al was associated with high reflectance. The nano-patterning, which was preserved in the mixed layer, determining the light trapping by multiple scattering, correlated with the high roughness and led to lower reflectance. A decrease was also revealed in photoluminescence emission both at UV and Vis excitation of the mixed layer, with the non-fullerene acceptor deposited on nano-patterned Al. An injector contact behavior was highlighted for all Al/mixed layer/ITO heterostructures by I-V characteristics in dark. The current increased, independently of acceptor (fullerene or non-fullerene), in the heterostructures with nano-patterned Al electrodes for shorter conjugation length polymer donors. [ABSTRACT FROM AUTHOR]

[Display omitted] • [(BuSn) 12 O 14 (OH) 6 ](NO 3) 2 exhibits high photosensitivity to EUV exposure. • Excellent stability of [(BuSn) 12 O 14 (OH) 6 ](NO 3) 2 irrespective of the post-exposure environment. • Superior resistance and selectivity of [(BuSn) 12 O 14 (OH) 6 ](NO 3) 2 to organic PR for Si and ACL during dry etching. • Nanoscale patterning of [(BuSn) 12 O 14 (OH) 6 ](NO 3) 2 with precise processing parameter controls. The semiconductor industry is currently transitioning to advanced extreme-ultraviolet lithography (EUVL) to address the challenges facing the use of photolithography in microprocessor and memory chip integration. This shift has sparked a surge in novel inorganic EUV photoresist research. However, several technical issues, such as insufficient EUV sensitivity, poor understanding of the photochemistry, and poor stability, have emerged. Here, the EUV sensitivity and stability of state-of-the-art tin oxo clusters are enhanced by integration with the photoactive nitrate anion to give [(BuSn) 12 O 14 (OH) 6 ](NO 3) 2 (TinNO 3). The findings of the study reveal that nitrate anions in TinNO 3 showing the photosensitivity as low as 32 mJ/cm2 and maintaining stability irrespective of the post-exposure environment. Furthermore, TinNO 3 possesses superior resistance to dry etching, enabling selective etching of Si and the amorphous carbon layer. Finally, through intensive optimization of the post-exposure bake parameters, photoresist-substrate adhesion, and development conditions, well-ordered CD 45 nm L/S patterns of TinNO 3 thin-film were achieved using ArF lithography. [ABSTRACT FROM AUTHOR]

Metasurfaces constructed from subwavelength nanostructures provide a route for surface coloring and optical encryption. Because of the high transmittance and refractive index, titanium dioxide (TiO2) is a candidate for visible metasurfaces, and its nano‐processing is essential for TiO2 metasurfaces. Herein, a direction‐controllable ultrafast laser nano‐patterning approach is reported for writing TiO2 nanostructures on titanium. The writing direction is controlled by adjusting the polarization of incident laser. Due to the localization of pulse energy inside the formed nanostructures, diverse planar patterns with feature sizes smaller than the diffraction limit are written. A strip‐shaped nanostructure with the width of 344 nm, parallel nanostructures with the center‐to‐center distance down to 370 nm, and a "THU" pattern with the height of 790 nm are achieved. Grating TiO2 nanostructures with various periods are fabricated for surface coloring and printing. Based on the anisotropic optical behaviors of grating‐type nanostructures, encrypting information by orthogonal scans is demonstrated as an optical encryption strategy. This nano‐patterning approach opens a route for the fabrication of TiO2 metasurfaces, and provides a new method for surface coloring and optical encryption. [ABSTRACT FROM AUTHOR]

Utilizing the controlled self-assembling of a giant surfactant, a bottom-up method for constructing line gratings with sub-10 nm resolution has been developed. Via a simple solvent vapor annealing procedure, the giant surfactant comprised of an oligomeric silsesquioxane (DPOSS) and polystyrene (PS) tail (i.e., DPOSS-PS) has been precisely self-assembled into perpendicularly oriented lamellae structures. A follow-up thermal annealing further significantly promotes the long-range ordering, giving rise to highly oriented and defect-free sub-10 nm line patterns (up to areas of several µm2). The solvent evaporation and thermal annealing process, together with the strong segregation strength (χN) of DPOSS-PS, play crucial roles in the self-orientation and width-reduction of the line patterns. This simple processing of the easy-accessed giant surfactants results in a facile and more economic approach for large-scale nano-sized line grating fabrication.

The properties of organic heterostructures with mixed layers made of arylenevinylene-based polymer donor and non-fullerene perylene diimide acceptor, deposited using Matrix Assisted Pulsed Laser Evaporation on flat Al and nano-patterned Al electrodes, were investigated. The Al layer electrode deposited on the 2D array of cylindrical nanostructures with a periodicity of 1.1 µm, developed in a polymeric layer using UV-Nanoimprint Lithography, is characterized by an inflorescence-like morphology. The effect of the nanostructuring on the optical and electrical properties was studied by comparison with those of the heterostructures based on a mixed layer with fullerene derivative acceptor. The low roughness of the mixed layer deposited on flat Al was associated with high reflectance. The nano-patterning, which was preserved in the mixed layer, determining the light trapping by multiple scattering, correlated with the high roughness and led to lower reflectance. A decrease was also revealed in photoluminescence emission both at UV and Vis excitation of the mixed layer, with the non-fullerene acceptor deposited on nano-patterned Al. An injector contact behavior was highlighted for all Al/mixed layer/ITO heterostructures by I-V characteristics in dark. The current increased, independently of acceptor (fullerene or non-fullerene), in the heterostructures with nano-patterned Al electrodes for shorter conjugation length polymer donors.

Zinc oxide has been the most versatile compound semiconductor, which is applied in diverse streams. Ion beams have been highly sophisticated and innovative tool for material modification and further characterization. In this article, we have systematically reviewed the ion beam synthesis, modification and further applications of ZnO thin films and nanocomposites. ZnO thin films synthesized, using low-energy ion beams, exhibit excellent quality. Ion implantation of ZnO leads to the improvement of electrical, optical and magnetic properties. Inert ion bombardment, on the one hand, results in the formation of uniform surface patterning on ZnO and on the other, produces nucleation centres for nanostructure growth. ZnO thin films also exhibit substantial radiation resistance, thus upon swift heavy ion irradiation, tuning of various properties can be explored with minimal/recoverable damage to the crystal lattice. In a few such studies, room temperature ferromagnetism, dissolution of metal cluster and recrystallization of ZnO have been observed. The precision of energetic ion beams and robustness of ZnO and its nanostructures have been explored for applications such as resistive random access memory, creation of hydrophophic and hydrophilic surfaces and dye degradation. [ABSTRACT FROM AUTHOR]

Current solutions to diagnose bacterial infections though reliable are often time-consuming, laborious and need a specific laboratory setting. There is an unmet need for bedside accurate diagnosis of infectious diseases with a short turnaround time. Moreover, low-cost diagnostics will greatly benefit regions with poor resources. Immunoassays and molecular techniques have been used to develop highly sensitive diagnosis solutions but retaining many of the abovementioned limitations. The detection of bacteria in a biological sample can be enhanced by a previous step of capture and enrichment. This will ease the following process enabling a more sensitive detection and increasing the possibility of a conclusive identification in the downstream diagnosis. This review explores the latest developments regarding the initial steps of capture and enrichment of bacteria from complex samples with the ultimate goal of designing low cost and reliable diagnostics for bacterial infections. Some solutions use specific ligands tethered to magnetic constructs for separation under magnetic fields, microfluidic platforms and engineered nano-patterned surfaces to trap bacteria. Bulk acoustics, advection and nano-filters comprise some of the most innovative solutions for bacteria enrichment. [ABSTRACT FROM AUTHOR]

AlN epilayers were grown on a 2-inch [0001] conventional flat sapphire substrate (CSS) and a nano-patterned sapphire substrate (NPSS) by metalorganic chemical vapor deposition. In this work, the effect of the substrate template and temperature on stress and optical properties of AlN films has been studied by using Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectrophotometer and spectroscopic ellipsometry (SE). The AlN on NPSS exhibits lower compressive stress and strain values. The biaxial stress decreases from 1.59 to 0.60 GPa for AlN on CSS and from 0.90 to 0.38 GPa for AlN on NPSS sample in the temperature range 80–300 K, which shows compressive stress. According to the TEM data, the stress varies from tensile on the interface to compressive on the surface. It can be deduced that the nano-holes provide more channels for stress relaxation. Nano-patterning leads to a lower degree of disorder and stress/strain relaxes by the formation of the nano-hole structure between the interface of AlN epilayers and the substrate. The low crystal disorder and defects in the AlN on NPSS is confirmed by the small Urbach energy values. The variation in bandgap (Eg) and optical constants (n, k) with temperature are discussed in detail. Nano-patterning leads to poor light transmission due to light scattering, coupling, and trapping in nano-holes.

The preparation of hierarchical nanoporous films is of great significance for their potential applications, but the development of a facile method to synthesize such films method remains a great challenge. In the current work, hierarchically honeycomb-patterned polydimethylsiloxane (PDMS) films with unique nanostructures were synthesized by simply depositing an acid solution, specifically consisting of a mixture of H 2 SO 4 , HNO 3 , and DI water, on PDMS films displaying regular concave structures. During the post-processing, secondary extrusions were generated on the surfaces of such PDMS films, leading to the formation of highly hierarchical honeycomb-shaped patterns. In the synthesis, the composition of the acid solution played a critical role in the formation and growth of the secondary extrusions. The morphological evolution of the PDMS films during the post-processing proceeded along different pathways depending on the experimental conditions of the process. Based on our results and observations, a plausible mechanism explaining the formation of the hierarchical honeycomb-shaped patterns and the morphological evolution during the synthesis was proposed. The developed approach provides a simple route for fabricating polymer films with unique hierarchical honeycomb-shaped patterns and without the need for any expensive or sophisticated lithographic patterning instruments. [ABSTRACT FROM AUTHOR]

This paper presents a comparative study between the properties of the heterostructures realized with single/multi layer organic (zinc phthalocyanine or/and fullerene) prepared on Si substrate between flat or patterned aluminum (Al) layer metallic electrode and multi layer ZnO/Au/ZnO transparent conductor electrode (TCE). The UV-Nanoimprint Lithography was used for the realization of a 2D array of nanostructures (holes/pillars) characterized by a periodicity of 1.1 μm and cylindrical shape: diameter = 400 nm and depth/height = 300 nm. The effect of the electrode patterning on the properties of the organic heterostructures was analyzed. For the samples with patterned Al electrode was remarked a slight red shift of the peaks in the reflection spectra determined by an increased interaction between the organic molecules in the delimited region of the patterned holes. The shape of the emission spectra at excitation with UV light showed a narrow intense peak around 500 nm associated with the intense resonance phenomena between the energy of the incident light and the surface plasmons in the patterned Al layer. The TCE followed the morphology of the organic film on which it was deposited. The significant differences between the morphology of the top layer in the heterostructures realized on flat and patterned Al are correlated with the total thickness of the successively deposited layers and with the particularities of the molecular arrangement, leading to the preservation or deleting of patterning. An injection contact behavior was evidence for most heterostructures built on flat and patterned Al. The slight increase in current at an applied bias <1 V in the heterostructure Si/Al/ZnPc/TCE is attributed to the larger interfacial area between the patterned Al electrode and ZnPc layer compared to the interface area between flat Al and ZnPc. A buffer layer of 1,4,5,8-naphthalen-tetracarboxylic dianhydride (NTCDA), sandwiched between the flat metallic electrode and organic film in the heterostructure Si/Al/C60/ZnPc/TCE has determined an increase in the current at low applied voltages. [ABSTRACT FROM AUTHOR]

Nanostructured surfaces have unique properties that can be used in many applications. Among different methods on creating nanostructured surfaces, we successfully assembled various nanostructures on one and the same high-density poly (acrylic acid) (PAA) grafted surfaces by conducting vacuum-mediated rapid phase separation in appropriately selected solvents. This not only increased the efficiency of creating surfaces with multiple structure patterns, also such nanostructured surfaces had improved biocompatibility and demonstrated liquid-like properties. Conducted experiments also proved that lanthanide ion Ce immobilized on nanostructured PAA grafted surfaces behaved the same as in the aqueous solution, attaining high illumination. In addition, good cell stretching and attaching experiment also present its potential in tissue engineering applications. [ABSTRACT FROM AUTHOR]

We report the transformation of smooth and hydrophilic mica surface to a patterned and hydrophobic surface by 12 keV Ar + and N + ion bombardment at oblique ion incidence. Periodic ripple pattern has been found on the mica surface when nitrogen like lighter or argon like heavier ions are bombarded at an angle 60° with respect to the surface normal. During ion bombardment the different components of multi-elemental mica are eroded at different rate; as a result surface chemistry is changed, as well as a surface ripple pattern is developed on the surface due to the generation of surface instabilities. The change of surface chemistry and presence of pattern change the hydrophilic nature of the mica surface. X-ray photoelectron spectroscopy (XPS) study of irradiated mica surface shows that the upper K atoms are sputtered most. The vertical and lateral dimensions of the surface patterns are controlled by varying the ion fluence. Contact angle measurement of un-irradiated and irradiated mica surface shows a certain change from hydrophilicity to hydrophobicity. The physicochemical changes of mica surface due to Ar + and N + ion bombardment have been discussed. [ABSTRACT FROM AUTHOR]

We address the solid state dewetting of ultra-thin and ultra-large patches of monocrystalline silicon on insulator. We show that the underlying instability of the thin Si film under annealing can be perfectly controlled to form monocrystalline, complex nanoarchitectures extending over several microns. These complex patterns are obtained guiding the dewetting fronts by etching ad-hoc patches prior to annealing. They can be reproduced over hundreds of repetitions extending over hundreds of microns. We discuss the effect of annealing temperature and patch size on the stability of the final result of dewetting showing that for simple patches (e.g. simple squares) the final outcome is stable and well reproducible at 720 °C and for ~ 1 μm square size. Finally, we demonstrate that introducing additional features within squared patches (e.g. a hole within a square) stabilises the dewetting dynamic providing perfectly reproducible complex nanoarchitectures of 5 μm size. [ABSTRACT FROM AUTHOR]

The controlled patterning of polymeric surfaces at the micro- and nanoscale offers potential in the technological development of small-scale devices, particularly within the fields of photovoltaics, micro-optics and lab- and organ-on-chip, where the topological arrangement of the surface can influence a system's power generation, optical properties or biological function - such as, in the latter case, biomimicking surfaces or topological control of cellular differentiation. One of the most promising approaches in reducing manufacturing costs and complexity is by exploitation of the self-assembling properties of colloidal particles. Self-assembly techniques can be used to produce colloidal crystals onto surfaces, which can act as replicative masks, as has previously been demonstrated with colloidal lithography, or templates in mold-replication methods with resolutions dependent on particle size. Within this context, a particular emerging interest is focused on the use of self-assembled colloidal crystal surfaces in polymer replication methods such as soft lithography, hot and soft embossing and nano-imprint lithography, offering low-cost and high-resolution alternatives to conventional lithographic techniques. However, there are still challenges to overcome for this surface patterning approach to reach a manufacturing reliability and process robustness comparable to competitive technologies already available in the market, as self-assembly processes are not always 100% effective in organizing colloids within a structural pattern onto the surface. Defects often occur during template fabrication. Furthermore, issues often arise mainly at the interface between colloidal crystals and other surfaces and substrates. Particularly when utilized in high-temperature pattern replication processes, poor adhesion of colloidal particles onto the substrate results in degradation of the patterning template. These effects can render difficulties in creating stable structures with little defect that are well controlled such that a large variety of shapes can be reproduced reliably. This review presents an overview of available self-assembly methods for the creation of colloidal crystals, organized by the type of forces governing the self-assembly process: fluidic, physical, external fields, and chemical. The main focus lies on the use of spherical particles, which are favorable due to their high commercial availability and ease of synthesis. However, also shape-anisotropic particle self-assembly will be introduced, since it has recently been gaining research momentum, offering a greater flexibility in terms of patterning. Finally, an overview is provided of recent research on the fabrication of polymer nano- and microstructures by making use of colloidal self-assembled templates. [ABSTRACT FROM AUTHOR]

Colorless polyimide (CPI) is a promising material for flexible substrates because of its excellent mechanical hardness, chemical durability, thermal stability, and high optical transmittance. In particular, its superior durability under heating and mechanical forces compared with other polymeric materials makes polyimide compatible for industrial applications. Thus, it has been actively investigated for use in preparing flexible and transparent substrates for optical devices. Nevertheless, there is little research on the direct pattering of CPI to form structures with various optical functions. In this research, a simple and cost-effective process involving the patterning of optically functional structures and imidization via thermal nanoimprint lithography (NIL) was developed. CPI films patterned with structures such as nanoscale and microscale cones were fabricated by thermal NIL, and their optical functions, including their anti-reflection and high scattering properties, were demonstrated by UV–vis analysis. Moreover, the patterned CPI film has an excellent thermal stability and a mechanical hardness up to 1.12 GPa; this value was nearly maintained even at 400 °C. Therefore, nano- to microscale optical patterns of CPI were successfully formed, and these structures are stable towards mechanical damage and high temperatures. [ABSTRACT FROM AUTHOR]

We report the ion beam based single step synthesis process of surface-patterned amorphous Silicon (a-Si) with a buried plasmon active nickel silicide layer for the realization of cost-effective, higher efficiency Silicon (Si) photovoltaic devices. Simultaneous amorphization, surface pattern formation and buried layer development are achieved by normal incidence 10 keV Ni 1+ ion bombardment on Si(100) surface at a fluence of 1 × 10 17 . Atomic Force Microscopy study shows rim-surrounded crater like periodic nanostructure on the surface whereas cross-sectional Transmission Electron Microscopy detects the amorphization and implant buried layer just below the surface. The distribution of implanted Ni ions and Si vacancies, obtained by the Monte Carlo simulation (SRIM) is consistent with the experimental results. Spatially resolved Electron Energy Loss Spectroscopy measurement detects that the buried layer is nickel silicide. The potential application of such nano-patterned and plasmon active system for future low-cost a-Si based higher efficient Photovoltaic devices is discussed. [ABSTRACT FROM AUTHOR]

Local electric field induced by a focused electron probe in silicate glass thin films is evaluated by the migration of cations. Extremely strong local electric fields can be obtained by the focused electron probe from a scanning transmission electron microscope. As a result, collective atomic displacements occur. This newly revised mechanism provides an efficient tool to write patterned nanostructures directly, and thus overcome the low efficiency of the conventional electron-beam lithography. Applying this technique to silicate glass thin films, as an example, a grid of rods of nanometer dimension can be efficiently produced by rapidly scanning a focused electron probe. This nanopatterning is achieved through swift phase separation in the sample, without any post-development processes. The controlled phase separation is induced by massive displacements of cations (glass modifiers) within the glass-former network, driven by the strong local electric fields. The electric field is induced by accumulated charge within the electron probed region, which is generated by the excitation of atomic electrons by the incident electron. Throughput is much improved compared to other scanning probe techniques. The half-pitch spatial resolution of nanostructure in this particular specimen is 2.5 nm. [ABSTRACT FROM AUTHOR]

Gold (Au) nanocrystal-embedded PDMS films were synthesized by simply depositing a precursor solution on the PDMS film. The resulting PDMS films, inside which many Au nanocrystals with dimensions smaller than 50 nm were uniformly embedded, showed unique nanostructured surface patterns. The morphological evolution of the films proceeded along different pathways depending on whether the film was chemically treated with O 2 plasma. The hybrid films were systematically characterized by carrying out scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy analyses. Mechanisms explaining the formation of the Au nanocrystal-embedded PDMS films and the morphological evolutions during the synthesis were proposed based on the results. The developed approach provides a simple route for fabricating metal nanocrystal-embedded polymer films with unique structures and without the need for special equipment. [ABSTRACT FROM AUTHOR]

In the present work, a soft lithographic process is used to create nanometer-sized line patterns of gold nanoparticles (Au NPs) on PEG-based hydrogels. Hereby nanometer-sized wrinkles on polydimethylsiloxane (PDMS) are first fabricated, then functionalized with amino-silane and subsequently coated with Au NPs. The Au NPs are electrostatically bound to the surface of the wrinkled PDMS. In the next step, these relatively loosely bound Au NPs are transferred to PEG based hydrogels by simple contacting, which we denote “nano-contact transfer”. Nano-patterned Au NPs lines on PEG hydrogels are thus achieved, which are of interesting potential in nano-photonics, biosensor applications (using SERS) and to control nanoscopic cell adhesion events. [ABSTRACT FROM AUTHOR]

Naturally-bioactive hydrogels like gelatin provide favorable properties for tissue-engineering but lack sufficient mechanical strength for use as implantable tissue engineering substrates. Complex fabrication or multi-component additives can improve material strength, but often compromises other properties. Studies have shown gelatin methacrylate (GelMA) as a bioactive hydrogel with diverse tissue growth applications. We hypothesize that, with suitable material modifications, GelMA could be employed for growth and implantation of tissue-engineered human corneal endothelial cell (HCEC) monolayer. Tissue-engineered HCEC monolayer could potentially be used to treat corneal blindness due to corneal endothelium dysfunction. Here, we exploited a sequential hybrid (physical followed by UV) crosslinking to create an improved material, named as GelMA+, with over 8-fold increase in mechanical strength as compared to regular GelMA. The presence of physical associations increased the subsequent UV-crosslinking efficiency resulting in robust materials able to withstand standard endothelium insertion surgical device loading. Favorable biodegradation kinetics were also measured in vitro and in vivo . We achieved hydrogels patterning with nano-scale resolution by use of oxygen impermeable stamps that overcome the limitations of PDMS based molding processes. Primary HCEC monolayers grown on GelMA+ carrier patterned with pillars of optimal dimension demonstrated improved zona-occludin-1 expression, higher cell density and cell size homogeneity, which are indications of functionally-superior transplantable monolayers. The hybrid crosslinking and fabrication approach offers potential utility for development of implantable tissue-engineered cell-carrier constructs with enhanced bio-functional properties. [ABSTRACT FROM AUTHOR]

We demonstrate fabrication of nano-patterned thin ALD (Atomic layer deposition) membrane (suspended/transferable) by using a bi-layer resist process where the bottom layer resist acts as a sacrificial layer. This method enables an all dry deterministic transfer of nano-patterned ALD membrane on desired substrate, allowing assembly of multitude of hetero-structures and functionalities that are not yet accessible. Unlike conventional ways of achieving patterned alumina membrane reported in literature our technique requires significantly less fabrication steps and paves the way for novel ALD membrane-based technology., (© 2023 IOP Publishing Ltd.)

Nanoscale science and technology has today mainly focused on the fabrication of nano devices. In this paper, we study the use of lithography process to build the desired nanostructures directly. Nanolithography on polymethylmethacrylate (PMMA) surface is carried out by using Atomic Force Microscope (AFM) equipped with silicon tip, in contact mode. The analysis of the results shows that the depth of scratches increases with the increase of applied normal force. The scanning velocity is also shown to influence the AFM patterning process. As the scanning velocity increases, the scratch depth decreases. The influence of time and number of scratching cycles is also investigated.

Predicting how proteins fold and adsorb onto surfaces is a complex problem of strong relevance to the health and environmental sectors. In this work, two nano-patterning techniques, namely focused ion beam (FIB) milling and atomic force microscopy (AFM) nanoindentation were used to develop hydrogenated amorphous carbon (a-C:H) model surfaces with similar nano-topography but different local composition. On the un-patterned surfaces, bovine plasma fibrinogen (BPF) resulted in a thicker and rougher adsorbed film than bovine serum albumin (BSA), although FTIR analysis indicated that, the secondary structure of the proteins changed similarly, with an increase of the β-sheet component (+ 27% and + 34% for BSA and BPF, respectively). AFM analysis on the FIB-patterned surfaces indicates that patterning can modify specific protein adsorption behaviors. Moreover, the patterns were compared by imaging the AFM tip/surface adhesive force for BSA adsorbed on either AFM tips or patterned surfaces. The results show an electrostatic interaction between the implanted Ga + and BSA surface, modifying the adsorption behavior and the adhesive force. Modelling this interaction gave an estimate of the surface charge per protein, a significantly lower value than in dilute solution (− 1.8e instead of -18e). This finding is indicative of protein misfolding, as detected in the FTIR analysis. [ABSTRACT FROM AUTHOR]

Three dimensional self-consistent field theoretic simulations have been performed to determine the equilibrium morphologies formed by linear ABC triblock polymer melts confined between two parallel plates that favor the middle block. Our primary goal is to elucidate the conditions under which the perpendicular lamella is stabilized, since this morphology plays a central role in many nanotechnology applications. Key factors, namely, the chain architecture, surface energy and the mismatch between the film thickness d and the bulk lamella period, LO, determine the final morphologies, e.g., perpendicular and parallel lamella, perforated lamella and wet substrate with parallel cylinders in the core, have been identified. Overall, our findings are fully consistent with the results of limited experimental studies focused on morphology development in thin films of triblock polymer melts. Finally, we have clearly demonstrated that ABC triblocks hold technological advantages over diblocks for nano-lithographic fabrications. [ABSTRACT FROM AUTHOR]

In the present work, a soft lithographic process is used to create nanometer-sized line patterns of gold nanoparticles (Au NPs) on PEG-based hydrogels. Hereby nanometer-sized wrinkles on polydimethylsiloxane (PDMS) are first fabricated, then functionalized with amino-silane and subsequently coated with Au NPs. The Au NPs are electrostatically bound to the surface of the wrinkled PDMS. In the next step, these relatively loosely bound Au NPs are transferred to PEG based hydrogels by simple contacting, which we denote “nano-contact transfer”. Nano-patterned Au NPs lines on PEG hydrogels are thus achieved, which are of interesting potential in nano-photonics, biosensor applications (using SERS) and to control nanoscopic cell adhesion events.

We have demonstrated that color-conversion efficiency can be enhanced through the use of non-radiative energy transfer between CdSe/ZnS core/shell colloidal quantum dots(QDs) and nitride multi-quantum well(MQW) in light emitting diodes(LEDs) having nano-patterned p-GaN. The nitride LEDs having nano-patterned p-GaN were fabricated by selective deep etching of p-GaN by using self-assembled ITO nano-dots as a etch mask. For comparison, we also fabricated the nitride LEDs having groove-etched p-GaN as well as the LEDs having a normal p-GaN layer. The results show that the LEDs having nano-patterned p-GaN showed the higher color conversion efficiency of 15.5 % and the improved effective internal quantum efficiency of 71 %. The enhanced efficiency can be attributed to sufficient close QD-MQW separation due to deep etching of p-GaN by using nano-patterning, which resulted in faster energy transfer rate of 2.47 ns for non-radiative QD-MQW energy-transfer. [ABSTRACT FROM AUTHOR]

This article reports on surface density variations that are accompanied by ion-beam-induced pattern formation processes on Si. The density profiles perpendicular to Si(100) surfaces were investigated after off-normal implantation with 5 keV Fe+ ions at fluences ranging from 1 × 1016 to 5 × 1017 ions cm−2. Ripple formation was observed for ion fluences above 1 × 1016 ions cm−2. X-ray reflectivity (XRR) revealed the formation of a nanometre subsurface layer with incorporated Fe. Using XRR, no major dependence of the surface density on the ion fluence could be found. In order to improve the surface sensitivity, extremely asymmetric X-ray diffraction was applied. Depth profiling was achieved by measuring X-ray rocking curves as a function of the decreasing incidence angle down to 0° using this noncoplanar scattering geometry. The density information was extracted from the dynamical Bragg shift of the diffraction peak caused by refraction of the X-ray beam at the air-sample interface. Simulations based on the dynamical theory of X-ray diffraction revealed a decrease of density for increasing ion fluence in a region close to the surface, caused by the amorphization and surface roughening. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the incorporation of iron atoms during nano-patterning of Si surfaces induced by 2keV Kr+ ion beam erosion under an off-normal incidence angle of 15°. Considering the low penetration depth of the ions, we have used X-ray reflectivity (XRR) and X-ray absorption near edge spectroscopy (XANES) under grazing-incidence angles in order to determine the depth profile and phase composition of the incorporated iron atoms in the near surface region, complemented by secondary ion mass spectrometry and atomic force microscopy. XRR analysis shows the accumulation of metallic atoms within a near surface layer of a few nanometer thickness. We verify that surface pattern formation takes place only when the co-sputtered Fe concentration exceeds a certain limit. For high Fe concentration, the ripple formation is accompanied by the enhancement of Fe close to the surface, whereas no Fe enhancement is found for low Fe concentration at samples with smooth surfaces. Modeling of the measured XANES spectra reveals the appearance of different silicide phases with decreasing Fe content from the top towards the volume. [Copyright &y& Elsevier]

Abstract: Irradiation of high-temperature superconducting (HTS) YBa2Cu3O7-d (YBCO) thin films with 75 keV He+ ions leads to a quasi-exponential increase of the in-plane (ρab) and the out-of-plane (ρc) resistivity in the normal state and to a non-linear decrease of the critical temperature Tc with ion dose. In situ electrical measurements at room temperature reveal an irradiation-induced reduction of resistivity anisotropy ρc/ρab and a slight relaxation of film resistivity after the ion irradiation is stopped. Ex situ measurements show a stretched-exponential relaxation of Tc and normal state resistivity that continues for several weeks after the ion irradiation. Irradiation of YBCO thin films by low-energy He+ ions through stencil masks results in local modification of the electrical and superconducting properties of the HTS material. We demonstrate that masked ion-beam lithography enables to produce structures smaller than 100 nm in size that have potential for applications in future superconducting nano-electronics. [Copyright &y& Elsevier]

In this work a process for nano-patterning of conventional giant magneto-resistive (GMR) spin valves by focused ion beam (FIB) technique is investigated. The sensors consisting of Si/SiO2[300]/Ta[5]/Ni79Fe21[6]/Co[1]/Cu[4]/Co[4]/\breakFeMn[20]/Ta[5]\ [thickness\ in\ nm] were produced by DC magnetron sputtering at a working pressure of 4 \mubar. For microstructuring an image reversal based photolithographic process was developed, with which lateral dimensions of several micrometers can be reached. By modeling the sensor resistance as function of the lateral dimensions an effective width reduction of \sim 1.7\ \mum is found. A further reduction of the sensor dimensions was reached by using a 30 kV Ga^+ ion beam from a commercial FIB microscope. After the FIB milling the sensor resistance shows a linear increase with the aspect ratio (length/width) down to \sim500 nm sensor width. With further reduction of the sensor width, the GMR vanishes. This behavior can be explained by Ga implantation and sputtering effects in a region extending more than 100 nm away from the actual FIB cut edge, which is supported by high resolution EDX analysis. [ABSTRACT FROM PUBLISHER]

Abstract: Hexagonally arrayed structures of the colloidal crystals with even surface is a good candidate for a master mold of soft lithography. By using high quality and robust 3D colloidal crystal mater mold, we successfully replicate the regular surface structure of colloidal crystal onto polystyrene (PS) thin films via a hot embossing technique, by using soft PDMS molds as a stamp. The replicated 2D patterns show high regular and periodic structures, with few defects over a large area. The periodicity of the patterns can be adjusted by varying the nanoparticle size of colloidal crystal master mold. Various hexagonally arrayed nanostructure patterns can be successfully fabricated, including close-packed and non-close-packed 2D arrays by the structural modification of 3D colloidal crystal templates. [Copyright &y& Elsevier]

Abstract: In this study, nano-patterned triangular photonic crystal arrays have been prepared on the surface of blue InGaN/GaN light-emitting diodes by focused ion beam technology. The nitride-based multilayer thin films were grown on c-plane (0001) sapphire substrates by low-pressure metal-organic chemical vapor deposition. The major emission peak wavelength was 468nm. The nano-patterned array structures were implemented using a dual-beam nanotechnology workstation SMI 3050. The acceleration voltage of Ga ion beam was 30kV, and the ion beam current was about 100pA. The air-hole diameter in the triangular array has been 150nm, while the periodicity ranged from 300nm to 800nm. The light–current measurements were carried out to reveal the light output intensity characteristics of the devices. In addition, the current–voltage study was shown with increased operation voltage from 3.0V to 4.05V while the period was decreased from 800nm to 300nm. [Copyright &y& Elsevier]

Abstract: Nano patterns of a TiO2-organic hybrid material have been fabricated by interference of surface plasmon on aluminum. The TiO2-organic hybrid materials were prepared by the sol–gel method, and were irradiated through an aluminum mask by a UV light. After the unreacted parts were removed, patterns were obtained on the films. The patterns of lines approximately 300nm in width and with a sub-100-nm height were obtained by controlling the UV irradiation time. It was confirmed that the patterns changed to anatase patterns by sintering at temperatures above 450°C. [Copyright &y& Elsevier]

Abstract: In this work patterned ZnO films were prepared at room-temperature by deposition of ∼5nm size ZnO nanoparticles using confined dewetting lithography, a process which induces their assembly, by drying a drop of ZnO colloidal dispersion between a floating template and the substrate. Crystalline ZnO nanoparticles exhibit a strong visible (525nm) light emission upon UV excitation (λ =350nm). The resulting films were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM). The method described herein presents a simple and low cost method to prepare crystalline ZnO films with geometric patterns without additional annealing. Such transparent conducting films are attractive for applications like light emitting diodes (LEDs). As the process is carried out at room temperature, the patterned crystalline ZnO films can even be deposited on flexible substrates. [Copyright &y& Elsevier]

Abstract: We have used ordered anodic alumina membranes as masks to create large scale ordered arrays of either holes or chemical islands on silica. Regularly spaced holes were obtained by direct etching of silica/silicon or glass substrates through the membranes used as etching masks. To create an array of chemically functional islands, the membrane is first glued on the substrate using a soft polymer and subsequently the polymer is etched gently though the mask. Finally organo-silane molecules are deposited through the alumina/polymer hybrid mask and the mask is removed chemically leaving nanoislands on the substrate. We anticipate that this technique will be useful in future biological and biomedical applications. [Copyright &y& Elsevier]

Abstract: Structural and compositional modification of InSb(001) single crystal surfaces induced by oblique incidence 2–5keV Ar and Xe ion irradiation have been investigated by means of scanning tunneling and atomic force microscopies, and time-of-flight mass spectroscopy of secondary ion emission. In general, ion-induced patterns (networks of nanowires, or ripples) are angle of incidence- and fluence-dependent. Temperature dependences (from 300 to 600K) of the RMS roughness and of the ripple wavelength have been determined for the samples bombarded with various fluences. Secondary ion emission from an InSb(001) surface exposed to 4.5keV Ar+ ions has been investigated with a linear TOF spectrometer working in a static mode. Mass spectra of the sputtered In+, Sb+ and In2 + secondary ions have been measured both for the non-bombarded (001) surface and for the surface previously exposed to a fluence of 1016 ions/cm2. In+ and In2 + intensities for the irradiated sample are much higher in comparison to the non-bombarded one, whereas Sb+ ions show a reversed tendency. This behavior suggests a significant In-enrichment at the InSb(001) surface caused by the ion bombardment. [Copyright &y& Elsevier]

Abstract: Nanopatterning of silicon surfaces by means of He+ ion implantation through self-organized colloidal masks is reported for the first time. Nanosphere lithography (NSL) masks with mask openings of 46–230nm width were deposited on Si(100) wafers. He+ ions were implanted through these masks in order to induce a local cavity formation and Si surface swelling. The surface morphology and the subsurface structure were studied using atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (XTEM), respectively, as a function of mask and implantation parameters. It is demonstrated that regular arrays of both individual hillocks and trough-like circular rings can be generated. [Copyright &y& Elsevier]

Abstract: Decisive advances in the field of nanosciences and nanotechnologies are intimately related to the development of new instruments and of related writing schemes and methodologies. Therefore we have recently proposed the exploitation of the nano-structuring potential of a highly focused ion beam (FIB) as a tool, to overcome intrinsic limitations of current nano-fabrication techniques and to allow innovative patterning schemes that are urgently needed in many nanoscience challenges. In this work, we will first detail a very high-resolution FIB instrument we have developed specifically to meet these nano-fabrication requirements. Then we will introduce and illustrate an advanced FIB processing scheme that is the fabrication of artificial nanopores. [Copyright &y& Elsevier]

Abstract: Micro-dot arrays and micro-walls of acrylic acid/melamine resin were fabricated on aluminum by anodizing, atomic force microscope (AFM) probe processing, and electrophoretic deposition. Barrier type anodic oxide films of 15nm thickness were formed on aluminum and then the specimen was scratched with an AFM probe in a solution containing acrylic acid/melamine resin nano-particles to remove the anodic oxide film locally. After scratching, the specimen was anodically polarized to deposit acrylic acid/melamine resin electrophoretically at the film-removed area. The resin deposited on the specimen was finally cured by heating. It was found that scratching with the AFM probe on open circuit leads to the contamination of the probe with resin, due to positive shifts in the potential during scratching. Scratching of the specimen under potentiostatic conditions at −1.0V, however, resulted in successful resin deposition at the film-removed area without probe contamination. The rate of resin deposition increased as the specimen potential becomes more positive during electrophoretic deposition. Arrays of resin dots with a few to several tens μm diameter and 100–1000nm height, and resin walls with 100–1000nm height and 1μm width were obtained on specimens by successive anodizing, probe processing, and electrophoretic deposition. [Copyright &y& Elsevier]

Abstract: Polyelectrolyte multilayers (PEMs) of poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) were successfully deposited onto novel nano-striped surfaces, which were generated using the cross-section surfaces of multilayer polymer films made from poly(ethylene-co-acrylic acid) (EAA) and linear low-density polyethylene (LLDPE). The procedure of PEM patterning consisted of three steps: nano-striped pattern formation, PEM deposition, and chemical crosslinking. It was observed that the PEMs were selectively deposited on the EAA layers and linked through covalent bonds, but those on LLDPE layers were washed off during sonication in water and methanol. In addition, the reactive moieties introduced by PEMs were successfully used to bond covalently with other important molecules, such as amine-terminated fluorescein. This kind of nano-striped surface with alternating wettability could serve as a template for many applications, including biomedical, separations, and electronics. [Copyright &y& Elsevier]

Abstract: In this work, we show the fabrication of colloidal nanocrystals (NCs) based waveguide photonic devices by exploiting a new lithographic approach for the nano-positioning of NCs. Our approach relies on the dispersion of CdSe/ZnS core/shell NCs into a layer of electro-sensitive resist (poly-methyl methacrylate, PMMA), which is subsequently patterned by means of electron beam lithography (EBL). This localization technique has been demonstrated by detecting high-resolution photoluminescence (PL) maps on an e-beam nano-patterned PMMA/NCs film through a confocal microscope. This technique has been exploited for the fabrication of distributed feedback (DFB) structures and distributed Bragg reflectors (DBR) suitable for the realization of in-plane waveguide lasers. A DFB structure has been obtained by patterning a periodical grating on a PMMA/NCs ridge waveguide. Two DBR have been similarly fabricated by creating quarter-wavelength thick alternated stripes of air and active blend; these structures have been exploited as front and back mirrors of an in-plane PMMA/NCs ridge cavity. In both cases, no following etching processes have been required, thus simplifying the steps needed for the fabrication of NCs based active photonic devices. [Copyright &y& Elsevier]

Abstract: Here, a new technology for uniform nano-patterning in a wide area is introduced. A μCP technique is applied in the opposite way of a traditional method. Using a flat PDMS stamp, sub-mm scale dot features of alkanethiol SAM are patterned onto rigid tips of micro Si structures, which deforms much less than those of PDMS structures. In order to minimize the diffusion of SAM ink in μCp process, the position of a stamp and a substrate is reversely changed, i.e., the Si substrate with micro structures is stamped onto the flat PDMS stamp which is placed on the bottom. Consequently, millions of nano dot features are uniformly patterned on the top of Si structures in a wide area (12mm×12mm). As one application, millions of uniform nano-needles array is fabricated in a large area using a nano-scale metal mask fabricated by inverse-μCP. Besides, this inverse-μCP technique will show another possibility to the nano-fabrication for bio-MEMS technology. [Copyright &y& Elsevier]