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Breaking the theoretical limits of external quantum efficiency (EQE) and obtaining quantum dot light‐emitting diodes (QLEDs) with high brightness, high efficiency, and low operating voltage is the basis of commercial applications in display and illumination. Devices with an EQE of over 20% can be realized by carrier equilibrium injection and light out‐coupling enhancement. However, it is difficult to synergistically enhance the performance of QLEDs by combining the light out‐coupling and the hole enhancement injection. In this paper, the injection enhancement of holes and the light out‐coupling are realized simultaneously only by nano‐imprint lithography (NIL). The π─π bonds of the PEDOT: PSS film treated by NIL demonstrate a molecular orientation perpendicular to the substrate, which improves the injection of the hole. The PEDOT: PSS patterned by NIL further presents improved light out‐coupling. Consequently, the EQE of red‐QLED is 30.42% with a synergistic enhancement factor of 61%, accompanying the maximum brightness increased by 8% to 125 200 cd m−2 at 4.6 V (Vturn‐on, 1.74 V). The EQE and brightness of green‐QLED increased by 38.9% and 34.3% to 24.16% and 279 700 cd m−2, respectively. Therefore, NIL will provide new insights into synergistically enhancing light out‐coupling and internal quantum efficiency to break through the performance of electroluminescence (EL). [ABSTRACT FROM AUTHOR]

Holographic display enabled by performing both amplitude modulation (AM) and phase modulation (PM) in a single Liquid Crystal on Silicon (LCoS)‐based Spatial Light Modulator (SLM) is introduced. Light propagation is manipulated in two different directions to perform both AM and PM via liquid crystals alignment layer which can be based on technologies by using photoalignment, nano‐imprint lithography (NIL), or unique over‐driving across Liquid Crystal (LC) layer of Vam‐Vpm method which are described and proved to be effective to tune incident light, control the polarization and propagation of the light entering the liquid crystals of a single LCoS‐based SLM (LCoS‐SLM) device. These methods enable holographic display and to alleviate the issues in using two separated SLMs trying to achieve the same. Further, the design techniques and methods to suppress adjacent pixels' crosstalk due to fringe field effect (FFE) [1] in 2D array are amenable to ensure higher resolution with pixel pitch down to 1¼m for compact size and higher pixel numbers beyond 8K×4K. It mitigates to reduce chores of pixel‐to‐pixel alignment, and to enhance image clarity and quality within a single LCoS‐SLM. It will be applicable to enable holographic display with such unique LCoS‐SLM particularly for AR/VR/MR smart glasses applications [18] [19] [20] once being fabricated in the future. [ABSTRACT FROM AUTHOR]

An in‐house‐developed nanoimprint lithography system is designed and developed to demonstrate a commercially viable method for creating Ni–Cu–Sn‐based narrow linewidth finger patterns capable of effectively reducing shadow loss in the front contact metallization on industrial silicon solar cells. Finite element analysis simulation studies estimate that an optimal force of 138 MPa is required to generate damage‐free patterns during nanoimprinting process. The poly (methyl methacrylate) residual layer is removed using reactive ion etching, which enhances the adhesion strength of Ni–Cu–Sn metallization. A low ohmic contact layer at the Si/Ni interface develops after sintering at 420 °C and formation of NiSi layer is confirmed through X‐ray photoelectron spectroscopy analysis as a function of Ar+ ion etching time. An average cell efficiency of 18.10% is achieved for silicon solar cells with micropatterned Ni/Cu/Sn‐based narrow linewidth front contact grid design, which can exhibit ≈1% enhancement in cell efficiency compared to commercial Ag screen‐printed solar cells. The Ni/Cu/Sn‐based front contact metallization can improve the cell performance by ≈6% compared to the commercial Ag screen‐printed metallization by reducing shadow loss and thereby indicating its suitability toward deploying for cost‐effective industrial solar cell manufacturing. [ABSTRACT FROM AUTHOR]

The industrial interest in the patterning of polymeric surfaces at the micro/nanoscale to include new functionalities has considerably increased during the last years. Hierarchical organization of micro/nanometric surface textures yields enhanced functional properties such as hydrophobicity, hydrophilicity, antibacterial activity, and optical or chromatic effects to cite some. While high accuracy methods to pattern hierarchical surfaces at the nanoscale have been developed, only some of them have been applied for high volume manufacturing with limited success, mainly because they rely on the use of expensive machinery and moulds or complicated inserts. Therefore, a method using low cost recyclable tooling and process conditions applicable to high-volume manufacturing is currently missing. In this work, a scalable and low-cost method to replicate hierarchical micro/nanostructured surfaces on plastic films is presented, which can be latter used as inlays for injection moulded parts with standard processing conditions. This method is used to demonstrate the feasibility of replicating three level hierarchical micro/nano textured surfaces using recyclable bio-based polymers (of high relevancy in the current plastic pollution context) achieving replication ratios above 90%, comparing the replication results with those obtained in polypropylene. The presence of the micro/nanotextures substantially increases the contact angle of all the polymers tested, yielding values higher than 90° in all the cases. Also, various mechanical properties of the replicated parts for all the polymers injected are characterized one and thirty days after the samples were manufactured, showing fairly constant values. This highlights the validity of the replicated surfaces, regardless of the biopolymers special crystallization characteristics. [ABSTRACT FROM AUTHOR]

Sol–gel chemistry and nano‐imprint lithography (soft‐NIL) can be combined for the fabrication of nano‐patterns with large vertical aspect ratio over large scales. The possibility to frame via soft‐NIL metal oxides materials featuring a large refractive index and low absorption coefficient, opens new avenues for light management. In spite of its importance, the integration of light emitters in these materials has been mostly investigated in flat layers, limiting their efficiency and versatility. Here it is shown that ZrO2 can be combined with light emitting Eu3+ ions and framed via soft‐NIL to form large arrays of pillars atop a 2D residual layer. The chemical precursor solutions and the nano‐imprint technique are developed for photonic metasurfaces sustaining sharp resonances ascribed to quasi‐guided modes and lattice modes, as accounted for by finite difference time domains simulations. These resonances enable for a record extraction of the Eu3+ forward emission up to ≈200 times with respect to the flat counterpart within a relatively small detection angle (≈ ±16° around the vertical direction). These results are relevant for light‐emitting displays, down‐ and up‐conversion processes for light detection such as scintillators for X‐ray and for light amplifiers based on rare‐earth emitters. [ABSTRACT FROM AUTHOR]

Zirconium oxide (ZrO2) is a well-studied and promising material due to its remarkable chemical and physical properties. It is used, for example, in coatings for corrosion protection layer, wear and oxidation, in optical applications (mirror, filters), for decorative components, for anti-counterfeiting solutions and for medical applications. ZrO2 can be obtained as a thin film using different deposition methods such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). These techniques are mastered but they do not allow easy micro-nanostructuring of these coatings due to the intrinsic properties (high melting point, mechanical and chemical resistance). An alternative approach described in this paper is the sol-gel method, which allows direct micro-nanostructuring of the ZrO2 layers without physical or chemical etching processes, using optical or nano-imprint lithography. In this paper, the authors present a complete and suitable ZrO2 sol-gel method allowing to achieve complex micro-nanostructures by optical or nano-imprint lithography on substrates of different nature and shape (especially non-planar and foil-based substrates). The synthesis of the ZrO2 sol-gel is presented as well as the micro-nanostructuring process by masking, colloidal lithography and nano-imprint lithography on glass and plastic substrates as well as on plane and curved substrates. [ABSTRACT FROM AUTHOR]

We demonstrated a two‐step tunable liquid crystal (LC) surface relief diffractive lens for presbyopia. The surface relief diffractive structure is fabricated by nano‐imprint lithography (NIL) roll‐to‐stage process. The LC lens is polarization‐independent with only one cholesteric liquid crystal (CLC) layer. The LC lens can be fabricated by LC one‐drop fill (ODF) process. This is useful for presbyopia vision correction. In this paper, we realized two‐step switched liquid crystal lens with optical power 0 and +2 diopters. [ABSTRACT FROM AUTHOR]

Optics manufacturing technology is predicted to play a major role in the future production of integrated photonic circuits. One of the major drawbacks in the realization of photonic circuits is the damage of optical materials by intense laser pulses. Here, we report on the preparation of a series of organic–inorganic hybrid photoresists that exhibit enhanced laser-induced damage threshold. These photoresists showed to be candidates for the fabrication of micro-optical elements (MOEs) using three-dimensional multiphoton lithography. Moreover, they demonstrate pattern ability by nanoimprint lithography, making them suitable for future mass production of MOEs.

Surface modifications are typically permanent in shape and chemistry. Herein, vinylogous urethane (VU) chemistry is presented as an easily accessible and versatile platform for rapid, facile, and reworkable surface modification. It is demonstrated that both physical and chemical post‐modification of permanent, yet dynamic elastic polymer networks are achieved. Surface patterns with high regularity are created, both via a straightforward replication process using a polydimethylsiloxane stamp (resolution ca. 10–100 µm) as well as using thermally activated nano‐imprint lithography (NIL) to form hole, pillar, or line patterns (ca. 300 nm) in elastic VU‐based vitrimers. The tunable, rapid exchange allows patterning at 130 °C in less than 15 min, resulting in an increased water contact angle and surface‐structure induced light reflection. Moreover, it is also demonstrated that the use of a single dynamic covalent chemistry makes it possible to strongly adhere to fluorinated and non‐fluorinated materials based on incompatible matrices, causing cohesive failure in a peel test. In a topography scan, the visibly transparent interface is shown to possess a continuous phase without a gap, while maintaining distinctively separated (non)‐fluorinated domains. Finally, this approach allowed for a straightforward coating of a non‐fluorinated material with a fluorinated monomer to minimize the overall fluorinated content. [ABSTRACT FROM AUTHOR]

Functional films with hydrophobic, oleophobic, anti-fouling, anti-icing, anti-bacterial and low reflectance properties can be produced by patterning nano- or micro-structures on films via nano imprint lithography. Here, an omni-phobic surface showing both hydrophobicity and oleophobicity was obtained without chemical surface treatment by increasing the surface roughness and deforming the pattern morphology using only nano imprint lithography and the oxygen-inhibited curing properties of polyurethane acrylate (PUA) resin. A tulip-shaped pattern imprinting process was designed in which microscale patterns were fabricated using a porous polydimethylsiloxane (PDMS) mold with high oxygen transmission. During ultraviolet (UV) curing, a curing inhibiting layer was formed by reaction with oxygen. Next, a PDMS pad was used for the pressurized curing of the curing inhibition layer to modify the micro scale structures. Finally, final curing of the deformed pattern was performed using ultra high-power UV light. The deformation of the pattern into tulip-like shapes with increased surface roughness was confirmed by microscopy, and contact angle measurement was performed to confirm omni-phobicity. The final cured imprinted samples showed water and oil contact angles reaching 169.2° and 115°, respectively; thus, the omni-phobic surface could be demonstrated by a tulip-shaped pattern imprinting process. [ABSTRACT FROM AUTHOR]

• Stainless steel stamps were structured by direct laser interference patterning. • Polymeric microlens arrays were imprinted using the laser processed stamps. • Microlens arrays were successfully used to enhance light out-coupling in OLEDs. The efficiency of organic light-emitting diodes (OLEDs) deposited on flat substrates is strongly limited by the total internal reflection at the air-substrate interface. An effective strategy to reduce the amount of substrate modes and enhance the light out-coupling into the air is attaching a microlens array (MLA) on the external surface of OLEDs. In this study, polymeric MLA with periods between 1.2 µm and 2.0 µm are patterned by plate-to-plate nano-imprint lithography using metallic stamps structured by direct laser interference patterning. When MLA with a spatial period of 2.0 µm and a structure depth of 200 nm are employed on red, green and blue OLEDs, the external quantum efficiency is increased to 11.4%, 6.6% and 12.7%, respectively, due to a reduction of internally reflected radiation at the air-MLA-glass interfaces. [ABSTRACT FROM AUTHOR]

Functional films with hydrophobic, oleophobic, anti-fouling, anti-icing, anti-bacterial and low reflectance properties can be produced by patterning nano- or micro-structures on films via nano imprint lithography. Here, an omni-phobic surface showing both hydrophobicity and oleophobicity was obtained without chemical surface treatment by increasing the surface roughness and deforming the pattern morphology using only nano imprint lithography and the oxygen-inhibited curing properties of polyurethane acrylate (PUA) resin. A tulip-shaped pattern imprinting process was designed in which microscale patterns were fabricated using a porous polydimethylsiloxane (PDMS) mold with high oxygen transmission. During ultraviolet (UV) curing, a curing inhibiting layer was formed by reaction with oxygen. Next, a PDMS pad was used for the pressurized curing of the curing inhibition layer to modify the micro scale structures. Finally, final curing of the deformed pattern was performed using ultra high-power UV light. The deformation of the pattern into tulip-like shapes with increased surface roughness was confirmed by microscopy, and contact angle measurement was performed to confirm omni-phobicity. The final cured imprinted samples showed water and oil contact angles reaching 169.2° and 115°, respectively; thus, the omni-phobic surface could be demonstrated by a tulip-shaped pattern imprinting process.

Today, the prevailing AR‐glasses displays are using waveguides. The light in‐ & outcoupling structures that these glasses contain can be made by UV nanoimprint lithography. Nanoimprint lithography tools have typical cycle times of around 40 imprints per hour, roughly resulting in 8M eyepieces per year made on 300mm wafers. To serve the projected mass market adoption, hundreds of imprint tools will be needed. An important question is how the eyepieces can be made more efficiently and cost‐effectively. The Morphotonics' Roll‐to‐Plate imprint technology enables high volume production, having the opportunity for large‐area imprinting, manufacturing multiple products in a single imprint step. [ABSTRACT FROM AUTHOR]

To achieve an effective surface-enhanced Raman scattering (SERS) sensor with periodically distributed “hot spots” on wafer-scale substrates, we propose a hybrid approach combining physical nano-imprint lithography and a chemical deposition method to form a silver microbead array. Nano-imprint lithography (NIL) can lead to mass-production and high throughput, but is not appropriate for generating strong “hot-spots.” However, when we apply electrochemical deposition to an NIL substrate and the reaction time was increased to 45 s, periodical “hot-spots” between the microbeads were generated on the substrates. It contributed to increasing the enhancement factor (EF) and lowering the detection limit of the substrates to 4.40 × 106 and 1.0 × 10−11 M, respectively. In addition, this synthetic method exhibited good substrate-to-substrate reproducibility (RSD < 9.4%). Our research suggests a new opportunity for expanding the SERS application.

Thermophotovoltaic (TPV) systems have attracted attention as promising power generation systems that can directly convert the radiant energy produced by the combustion of fuel into electrical energy. However, there is a fundamental limit of their conversion efficiency due to the broadband distribution of the radiant spectrum. To overcome this problem, several spectrally selective thermal emitter technologies have been investigated, including the fabrication of photonic crystal (PhC) structures. In this paper, we present some design rules based on finite-a difference time-domain (FDTD) simulation results for tungsten (W) PhC emitter. The W 2D PhC was fabricated by a simple nano-imprint lithography (NIL) process, and inductive coupled plasma reactive ion etching (ICP-RIE) with an isotropic etching process, the benefits and parameters of which are presented. The fabricated W PhC emitter showed spectrally selective emission near the infrared wavelength range, and the optical properties varied depending on the size of the nano-patterns. The measured results of the fabricated prototype structure correspond well to the simulated values. Finally, compared with the performance of a flat W emitter, the total thermal emitter efficiency was almost 3.25 times better with the 2D W PhC structure. [ABSTRACT FROM AUTHOR]

This paper explains how large area Roll‐to‐Plate (R2P) Nanoimprinting is combined with Reactive Ion Etching (RIE) to address the emerging needs of a variety of demanding products. In this process sequence, the scalable R2P imprint process is used to apply a structured mask to the functional surface. In a subsequent etching step the texture is transferred into the layer underneath. Using nanoimprinting and dry‐etching in combination is a powerful method for creating large‐area metal structured surfaces or optical structures in glass while improving mechanical durability and optical clarity at reduced costs and in larger volumes. [ABSTRACT FROM AUTHOR]

The requirement of high-temperature calcination for titanium dioxide in (solid-state) dye-sensitized solar cells (DSSCs) implies challenges with respect to reduced energy consumption and the potential for flexible photovoltaic devices. Moreover, the use of dye molecules increases production costs and leads to problems related with dye bleaching. Therefore, fabrication of dye-free hybrid solar cells at low temperature is a promising alternative for current DSSC technology. In this work the authors fabricate hierarchically structured titania thin films by combining a polystyrene-block-polyethylene oxide template assisted sol-gel synthesis with nano-imprint lithography at low temperatures. The achieved films are filled with poly(3-hexylthiophene) to form the active layer of hybrid solar cells. The surface morphology is probed via scanning electron microscopy and atomic force microscopy, and the bulk film morphology is examined with grazing incidence X-ray scattering. Good light absorption by the active layer is proven by UV-vis spectroscopy. An enhancement in light absorption is observed and ascribed to light scattering in mesoporous titania films with imprinted superstructures. Accordingly a better photovoltaic performance is found for nano-imprinted solar cells at various angles of light incidence. [ABSTRACT FROM AUTHOR]

In order to increase the efficiency of high performance silicon heterojunction solar cells even further, it is paramount to increase the photoelectric current by enhancing the amount of light being captured within the absorber. Therefore, to reduce the parasitic absorption in the other layers, optoelectronically favorable hydrogenated nanocrystalline silicon oxide films can substitute the commonly used hydrogenated amorphous silicon layers. In this work, we systematically investigate the combination of hydrogenated nanocrystalline silicon oxide and front side nano-imprint textures as anti-reflection layers in silicon heterojunction solar cells. Ultimately, we were able to tune the parasitic absorption via variation of the front surface field layer and enhance the short-circuit current of the planar solar cells by about 2 mA cm−2 due to a random silicon pyramid textured imprint layer. A maximum active area efficiency of 20.4% was achieved with a short-circuit current of 37.7 mA cm−2. [ABSTRACT FROM AUTHOR]

In this work, we report on the prototyping of thin-film silicon tandem solar cells with periodic light-trapping textures. Our approach combines an industrial applicable nano-imprint process, for the fabrication of advanced light management concepts, with state-of-the-art thin film silicon solar cell technology. In a joint experimental effort between project partners of the European thin-film silicon project 'Fast-Track', we demonstrate that optimal periodic light-trapping nano-textures at the front-side of a multi-junction solar cell enhance the power conversion efficiency of the device in comparison to solar cells with conventional textured TCO (transparent conductive oxide) front contacts from 11.7% to 12.1%. This improved power conversion efficiency is mainly driven by an enhancement of the short-circuit current density through the use of periodic light-trapping nano-textures. [ABSTRACT FROM AUTHOR]

The monolithic integration of 1.5-µm four channels phase shift distributed feedback lasers array (DFB-LD array) with 4×1 multi-mode interference (MMI) optical combiner is demonstrated. A home developed process mainly consists of butt-joint regrowth (BJR) and simultaneous thermal and ultraviolet nanoimprint lithography (STU-NIL) is implemented to fabricate gratings and integrated devices. The threshold currents of the lasers are less than 10 mA and the side mode suppression ratios (SMSR) are better than 40 dB for all channels. Quasi-continuous tuning is realized over 7.5 nm wavelength region with the 30 °C temperature variation. The results indicate that the integration device we proposed can be used in wavelength division multiplexing passive optical networks (WDM-PON). [ABSTRACT FROM AUTHOR]

Abstract: Using an ion source based on photoionization of laser-cooled lithium atoms, we have developed a scanning ion microscope with probe sizes of a few tens of nanometers and beam energies from 500eV to 5keV. These beam energies are much lower than the typical operating energies of the helium ion microscope or gallium focused ion beam systems. We demonstrate how low energy can be advantageous in ion microscopy when detecting backscattered ions, due to a decreased interaction volume and the potential for surface sensitive composition analysis. As an example application that demonstrates these advantages, we non-destructively image the removal of a thin residual resist layer during plasma etching in a nano-imprint lithography process. [Copyright &y& Elsevier]

Nanoscale structures have been at the core of research efforts dealing with integration of nanotechnology into novel electronic devices for the last decade. Because the size of nanomaterials is of the same order of magnitude as biomolecules, these materials are valuable tools for nanoscale manipulation in a broad range of neurobiological systems. For instance, the unique electrical and optical properties of nanowires, nanotubes, and nanocables with vertical orientation, assembled in nanoscale arrays, have been used in many device applications such as sensors that hold the potential to augment brain functions. However, the challenge in creating nanowires/nanotubes or nanocables array-based sensors lies in making individual electrical connections fitting both the features of the brain and of the nanostructures. This review discusses two of the most important applications of nanostructures in neuroscience. First, the current approaches to create nanowires and nanocable structures are reviewed to critically evaluate their potential for developing unique nanostructure based sensors to improve recording and device performance to reduce noise and the detrimental effect of the interface on the tissue. Second, the implementation of nanomaterials in neurobiological and medical applications will be considered from the brain augmentation perspective. Novel applications for diagnosis and treatment of brain diseases such as multiple sclerosis, meningitis, stroke, epilepsy, Alzheimer's disease, schizophrenia, and autism will be considered. Because the blood brain barrier (BBB) has a defensive mechanism in preventing nanomaterials arrival to the brain, various strategies to help them to pass through the BBB will be discussed. Finally, the implementation of nanomaterials in neurobiological applications is addressed from the brain repair/augmentation perspective. These nanostructures at the interface between nanotechnology and neuroscience will play a pivotal role not only in addressing the multitude of brain disorders but also to repair or augment brain functions. [ABSTRACT FROM AUTHOR]

In this study, we introduce a process for fabrication of nano-sized structural arrays on glass using modified nano-imprint patterning. A PVC (polyvinyl chloride) stamp was prepared by hot embossing, and a Cr-oxide-pattern etch-mask was used. The etch-mask was formed by oxidizing the surface of exposed Cr region by oxygen plasma treatment at room temperature. The fabrication of the etch-mask was conducted by immersing the locally oxidized Cr pattern in resin remover and Cr-etchant. The residual UV resin and un-oxidized Cr pattern were selectively removed, resulting in the obvious array of Cr-oxide etch-mask-pattern. The array of glass nano-structures was formed by reactive ion etching (RIE) using CF and Ar gas discharge. After removing the Cr-oxide mask, the final nano-structure had a height of 40 nm and a diameter of 170 nm, which was slightly less than the diameter of the original master-mold. The plasma treatment gave rise to a rough glass surface with root-mean-square (RMS) roughness of 29.25 nm, while that of bare glass was 0.66 nm. A high optical transmittance due to reduction in reflectance was observed at the plasma-treated rough surface, as well as for the array of nano-structures. The highest measured optical transmittance was 97.2% at a wavelength of 550 nm; an increase of about 7.2% compared to bare glass. [ABSTRACT FROM AUTHOR]

Anti-reflective coatings (ARCs) are used to lower the reflection of light on the surface of a substrate. Here, we demonstrate that the two main drawbacks of moth eye-structured ARCs-i.e., the lack of suitable coating materials and a process for large area, high volume applications-can be largely eliminated, paving the way for cost-efficient and large-scale production of durable moth eye-structured ARCs on polymer substrates. We prepared moth eye coatings on polymethylmethacrylate (PMMA) and polycarbonate using wafer-by-wafer step-and-flash nano-imprint lithography (NIL). The reduction in reflection in the visible field achieved with these coatings was 3.5% and 4.0%, respectively. The adhesion of the coating to both substrates was good. The moth eye coating on PMMA demonstrated good performance in three prototypical accelerated ageing tests. The pencil hardness of the moth eye coatings on both substrates was <4B, which is less than required for most applications and needs further optimization. Additionally, we developed a roll-to-roll UV NIL pilot scale process and produced moth eye coatings on polyethylene terephthalate (PET) at line speeds up to two meters per minute. The resulting coatings showed a good replication of the moth eye structures and, consequently, a lowering in reflection of the coated PET of 3.0%. [ABSTRACT FROM AUTHOR]

We have fabricated polymer-based 2-dimensional photonic crystals that play a key role in enhancing the fluorescence of DNA intercalators. Highly ordered 2-dimensional photonic crystals possessing triangle-shaped and nm-sized hole arrays were fabricated on a 100 μm thick polymer film using nano-imprint lithography. Samples of double-stranded DNAs (sizes: 4361 and 48502 bp; concentration: 1 pM to 10 nM) were adsorbed on the surface of the 2-dimensional photonic crystal by electrostatic interactions and then treated with intercalators. It is found that the fluorescence intensity of the intercalator is enhanced by a factor of up to 10 compared to the enhancement in the absence of the 2-dimensional photonic crystal. Fluorescence intensity increases with increasing length and concentration of the DNAs. If the 2-dimensional photonic crystal is used as a Bragg reflection mirror, the enhancement of fluorescence intensity can be easily observed using a conventional spectrofluorometer. These results suggest that the printed photonic crystal offers a great potential for highly sensitive intercalator-based fluorescent detection of DNAs. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Using modern laser fabrication techniques such as two-photon polymerisation (2PP), complex 3D and planar structures with the resolutions down to 100 nm can be achieved. Advantages of 2PP can be exploited by combining it with the nano-imprint lithography (NIL). We report on the fabrication of masters by 2PP and its replicas by the soft NIL technique using poly(dimethylsiloxane) (PDMS). With PDMS stamps, very reproducible replicas of the master can be created. The stamp surface quality can be better than that of the master due to hydrostatic pressure during the stamp fabrication. Putting the stamp under stress allows the fabrication of structures with controllable reduction of the structural dimensions in one direction compared to the original master. Experimental investigations of the shape transfer fidelity and surface roughness of the replicas are presented. [ABSTRACT FROM AUTHOR]

Abstract: In this article we describe the design of a universal ultra-precision positioning platform to be used in the development of many different nano-manufacturing processes. The system incorporates the concept of employing different interchangeable manufacturing and characterization tools with one ultra-precision positioning system. A multi-linear-motor-driven XY planar stage floating on a thin film of air is used to traverse a substrate through a 10mm×10mm travel range with an XY linear position resolution of less than 1nm and an angular resolution about the Z axis of 0.05μrad over a range of about a degree (determined by plane mirror interferometer optics). A piezoelectric transducer (PZT) driven tripod positioning system is used to align each manufacturing and characterization tool with the substrate through a travel range of 40μm along the Z axis and 245μrad of rotation about the X and Y axes. The mechanical design, an overview of the system error analysis, preliminary component performance results, and the results of the first micro-imprint fabricated with the machine are presented. [Copyright &y& Elsevier]

Abstract: Electron assisted atomic force microscope (AFM) lithography is a relatively simple and flexible lithography method with a resolution of below 100nm. An electron beam (EB) resist is patterned by scanning a fine needle (cantilever) on the resist surface while applying a voltage. However, one of the problems of electron assisted AFM lithography is wear of the cantilever apex, which causes changes in the line width and impedes long-distance patterning. To overcome this problem, we examined ways of improving the lifespan of the cantilever during electron assisted AFM lithography by coating the EB resist with a fluorinated silane coupling agent (Optool DSX) as a low-friction layer and by coating the cantilever apex with platinum (Pt) to protect the cantilever. Through these two means, we achieved long-distance (more than eight times) patterning without any significant change in line width (less than a few nanometers) using the electron assisted AFM lithography system (MPS-1000, Sumitomo Precision Products Co. Ltd.). The delineated distance was 2000μm (=2mm) and the line width remained constant at 60nm from start to finish. It took 34min to complete the patterning. [Copyright &y& Elsevier]

Abstract: Cryogenic silicon etching using SF6–O2 at the sub-50 nm scale has been developed for nano-electromechanical systems (NEMS) and nano-photonics systems where high aspect ratio trenches are desired. It was found that the SF6–O2 chemistry at cryogenic temperatures (−100 to −130°C) provides the best combination of etch rate, selectivity, and profile control for the smallest trenches etched. The profile can be well controlled with aspect ratios on the order of 8:1 for 20nm wide trenches. The various etch parameter trends will be discussed along with methods to achieve the optimal profiles and etch rates. [Copyright &y& Elsevier]

Abstract: Hydrophobic fluorocarbon polymer films have been used as anti-sticking and releasing coatings for templates in nano-imprint lithography, but have poor durability against repeated high pressure pressing processes. The addition of nitrogen into fluorocarbon-based gas plasma can provide nitrided fluorocarbon polymer films, as confirmed by Fourier-transform infrared spectroscopy. Fluorocarbon and nitrided fluorocarbon films have almost the same 110.0° contact angle with water drops. The nitrided fluorocarbon films are harder and significantly enhance durability as anti-sticking layers. Durability enhancement has been confirmed by fabricating replicas with silicon templates using nitrided fluorocarbon anti-sticking layers. [Copyright &y& Elsevier]

Abstract: Because of increase in demand for clean energy sources, photovoltaic device is becoming more important as a new power plant. To replace fossil fuels with photovoltaics, generating electricity with solar cells should meet cost effectiveness and high efficiency. An anti-reflection technique is one of the effective methods to achieve high efficiency. To reduce the reflection at the surface of concentrated photovoltaic device, a nanometer scale dot-pattern array was formed on the surface of GaInP/Ga(In)As/Ge solar cells by nano-imprint lithography. Since this nano-pattern is smaller than the wavelength of visible light, the effective refractive index near the surface changes gradually. Thus, the reflection of the light at the surface with moth-eye structure can be effectively reduced for overall spectral region. As a result, a solar cell with the moth-eye pattern as an anti-reflection layer showed lower reflectance and enhanced total conversion efficiency, compared to a solar cell without a moth-eye patterned layer. The patterned solar cell was characterized using UV–vis spectrophotometer, atomic force microscope (AFM) and scanning electron microscope (SEM), and its total conversion efficiency was measured by solar simulator. [ABSTRACT FROM AUTHOR]

Abstract: With the aim of preparing nano-hole array for bit patterned media of ultra high density data storage, fabrication and imprint-ability of Pd–Cu–Ni–P glassy alloy thin film was investigated. By using a pulsed-laser deposition method, the Pd-based glassy alloy thin film was successfully fabricated. The thermal characteristics of the obtained film were very close to those of the melt-spun glassy alloy ribbon. The obtained film has very smooth surface and high hardness, which are suitable for nano-imprint processing. Nano-imprint-ability of the obtained film is demonstrated by using dot array mold with a dot diameter of 30nm. The periodic dot pattern of the mold was precisely transcribed. These results suggest that the Pd–Cu–Ni–P glassy alloy thin films are potential nano-imprinting materials for fabricating bit patterned media. [ABSTRACT FROM AUTHOR]

This paper describes the fabrication process of CoPt nandot arrays on a glass disk substrate with a CoZrNb underlayer as a soft magnetic underlayer (SUL) by using an electrochemical process, and also the analysis on the magnetic properties of these fabricated CoPt nanodot arrays.We formed nano-patterned substrates by UV-nanoimprint lithography (UV-NIL) on the glass disk substrate. CoPt was electrodeposited into the nano-patterned substrates optimizing the electrodeposition condition and bath composition as well as a Cu intermediate layer. The construction of the nanodot arrays were CoPt nanodot arrays (20 nm)/Cu (<5 nm)/CoZrNb (100 nm)/Cr (5 nm)/Glass disk. Magnetic signals were clearly observed on the dc magnetized state and multi domain were observed in each nanodot on the ac magnetized state by magnetic force microscopy (MFM). The perpendicular coercivity of the CoPt nanodot arrays was 430 kA/m. These results showed electrochemical process can be used for the manufacture of magnetic recording media. [ABSTRACT FROM AUTHOR]

The increasing demand for micro-products and components can be met only partly by the lithography-based micro-electromechanical systems fabrication processes that originated from the silicon-based microelectronics revolution of the late twentieth century. In particular, such processes have limitations when applied to new micro-devices which require the use of a variety of materials and complex 3D microstructures with high aspect ratios. In this context, the paper presents technologies complementary to lithography-based processes for the manufacture of devices or components incorporating micro- and nano-scale features. More specifically, special attention is given to the main findings obtained over the last 5 years from the authors’ research programme on a range of micro- and nano-manufacturing technologies, namely, micro-electrodischarge machining, laser ablation, micro-milling, focussed-ion beam machining, micro-injection moulding, nano-imprint lithography, hot embossing and electroforming. [ABSTRACT FROM AUTHOR]

Abstract: A new printing technology is described, which is capable of printing metallic electrodes onto organic layers. Electrodes are defined on top of a sacrificial layer by optical or nano-imprint lithography. To increase the stability of the process the electrodes are coated with several backing layers. The metallic features are released from the sacrificial layer by immersion in water and subsequently transferred onto the target substrate. By the use of nano-imprint lithography, feature sizes below 100nm are achieved. The strengths of the printing technology are high integration density, versatility and reproducibility. [Copyright &y& Elsevier]

Abstract: A nanometer scale polymer pattern was formed on the surface of a glass plate by nano-imprint lithography with the aim of reducing the reflection of light at the surface. Since this polymeric nano-pattern is smaller than the wavelength of light, the effective refractive index near the surface changes gradually, and reduces the amount of reflection. Such a nano-pattern was formed on one or both sides of a glass plate, which will be used as the protective layer for solar cell devices. As a result, a solar cell with a both-side patterned glass plate as a protective layer showed up to 2.5% increase (5.14–5.27%) in total conversion efficiency, compared to a solar cell with a bare glass plate. [Copyright &y& Elsevier]

Abstract: The fast cure kinetics of an ultraviolet (UV) light-curable resin for UV nano-imprint lithography (UV-NIL) was measured using a differential photocalorimeter (DPC). A simple phenomenological model was formulated to describe the curing behaviors of the UV-curable resin, i.e., the initial fast reaction rate at a small degree of cure and the autocatalytic reaction rate at a larger degree of cure. Kinetic model parameters were best fitted to the measured cure rate by using an error minimization technique. The practical applicability of the phenomenological model developed herein was demonstrated by a good agreement between the measured and modeled curing behaviors of the UV-curable resin. The effect of cure conditions on the estimated kinetic model parameters was also investigated. [Copyright &y& Elsevier]

Abstract: The use of nano-objects to make the active part of reproducible nanodevices requires their controlled assembling on specific areas of substrates. In this work, we propose to use van der Waals interactions to assemble selectively gold particles covered by alkyl-thiol ligands on hydrophobic OctadecylTriMethoxySilane (OTMS) patterns defined on SiO2/Si substrates by a process combining nano-imprint lithography (NIL) or high resolution electron beam lithography (HREBL) and atmospheric chemical vapor deposition (CVD) of silane. A study by atomic force microscopy (AFM) reveals that homogeneous patterns of OTMS self-assembled monolayers, extending on several square millimeters, have been made. These OTMS patterns, with a lateral dimension ranging from 2μm down to 50nm, can be located at a precise place of a nanodevice, for example, between nanoelectrodes. Preliminary results of selective nanoparticle deposition on these chemical patterns are presented. [Copyright &y& Elsevier]

Recent progress in the development of patterned magnetic recording media is presented, focusing on the results of patterned media fabricated by a self-assembled mask process. Several issues such as fabrication process, flyability, and signal processing have been discussed so far. However, recent progress seems to resolve these problems. A fabrication process using nano-imprint lithography is a possible solution in terms of productivity. Good results for flyability have been reported for discrete track recording media. Certain advantages with respect to signal processing have been reported. Although problems remain to be resolved, patterned media is expected to be commercialized following the introduction of the discrete track media, as a high density perpendicular magnetic recording media. [ABSTRACT FROM AUTHOR]

Abstract: In order to utilize Ag nano-particles into micro–nano-devices, they need to be selectively deposited as a sub-micrometer scale to form the patterns. Self-assembled monolayer (SAM) can modify the surface properties of substrate according to its terminal functional groups. Especially, the hydrophobic SAM can drastically reduce the surface energy of substrate and it may be applied to the various selective deposition applications. In this study, the trichlorosilane based hydrophobic SAM was patterned by the zero-residual layer nano-imprint lithography and Ag nano-particles were selectively deposited to form a sub-micrometer sized patterns. [Copyright &y& Elsevier]

Abstract: DRAM is the most commonly used memory due to many advantages such as high speed and easy manufacturability owing to its simple structure, but is volatile. On the other hand, flash memory is non-volatile, but has other disadvantages such as slow speed, short lifetime, and low endurance for repetitive data writing. Compared to DRAM and flash memory, PRAM (Phase-change Random Access Memory), which is a non-volatile memory using a reversible phase change between amorphous and crystalline state, has many advantages such as high speed, high sensing margin, low operating voltage, and is being pursed as a next generation memory. Being able to pattern and etch phase change memory in nanometer scale is essential for the integration of PRAM. This study uses the Nano-Imprint Lithography (NIL) for patterning the PRAM in nanometer scale which is believed to be a future lithography technology that will replace the conventional Photo Lithography. Si wafers coated with SiO2 were used as substrates, and Ge2Sb2Te5 (GST) films with the thicknesses of 100 nm were deposited by RF sputtering. Poly-benzylmethacrylate based polymer patterns were formed using NIL on the surface of GST films, and the GST films were etched using Cl2/Ar plasma in an Oxford ICP (inductively coupled plasma) etcher. [Copyright &y& Elsevier]

Abstract: Nano-imprint lithography is attracting attention as a low cost method for printing nanometer-scale geometries and has obtained placement on the International Technology Roadmap for Semiconductors as a potential lithography solution at the 32 and 22nm fabrication nodes [International Technology Roadmap for Semiconductors, 2003 ed.]. As a result, nano-imprint technology and infrastructure development related to template infrastructure, imprinting capabilities, and wafer-level pattern transfer processes are essential to successfully make the transition from research and development to a viable manufacturing processing technique suitable for multiple applications. Motorola Labs has been focusing on developing the template and wafer-level processes while optimizing the imprinting process and collaborating with external partners to optimize both the inspection and repair of imprint templates. This paper reviews recent results of the above-mentioned focus areas. [Copyright &y& Elsevier]

The potential benefits of patterning discrete tracks onto a disk for magnetic data storage have long been investigated. A practical process for manufacturing a cost-effective discrete track recording (DTR) medium has prevented such a disk from being introduced into a product. In this paper, a process utilizing nano-imprint lithography techniques to create a land and groove structure on the surface of a disk substrate will be described. Design considerations for the geometry of the structure, as well as of the magnetic write and read widths of the head, are discussed. Data showing the magnetic characteristics and recording performance of a DTR medium are also presented. [ABSTRACT FROM AUTHOR]

Abstract: The nano-imprinting lithography is regarded as one of the most promising technologies for nano-sized pattern fabrication and is being focused as a key technology for the mass production. However, significant progress must be made to improve uniform imprinting over large area, low temperature and low pressure operation and imprinting with minimized residual layer. A unique pressure vessel type imprinting system was used to imprint the patterns as small as 150 nm over whole 4-in. diameter wafer with near zero residual layer. To cover the whole surface of 100 mm diameter Si wafer, an array of 18 mm by 18 mm quartz stamps was used as an imprint stamp. UV curable benzylmethacrylate (C11H12O2) based monomer solution is used as an imprinting resin in this study. Near zero residual nano-imprinting over 100 mm diameter Si wafers was successfully demonstrated with 25 atm of imprinting pressure by using liquid state monomer based UV curable resin. [Copyright &y& Elsevier]