This PDF file contains the front matter associated with SPIE Proceedings Volume 10354, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Three-dimensional (3D) laser lithography has become a versatile, reliable, and widespread workhorse for fabricating 3D micro- and nanostructures. I will illustrate the current state-of-the-art by selected examples, including free-form micro-optics, 3D optical and other metamaterials, as well as functionalized 3D scaffolds for biological cell culture. I will speculate about near-term industrial applications and outline remaining technological challenges regarding spatial resolution, scalability, and multi-material 3D nano-printing.

Further developments of miniaturized spectrometry systems require tunable Fabry-Pérot-Interferometers (FPI). A main part of the FPI is the reflector, which is usually realized as a stack of alternating dielectric layers with high and low refractive index. To achieve high reflectivity adequate material property homogeneity for each layer is needed. For stacks with larger number of layers not only the integration with MEMS processes is challenging. Particularly stack structuring and the achievement of process compatibility to moveable MEMS structures are important.

As an alternative to the alternating layer stack reflector, nanostructured photonic crystal (PhC) reflectors indicate equivalent performance by using only one layer leading to a minimized reflector complexity. This contribution presents a novel PhC reflector consisting of a 400 nm thin moveable nanostructured LP-CVD Si₃N₄ membrane realizing an aperture of 0.5 mm and 1 mm for reflectivity in the VIS range. Manufacturing of the reflectors is done on 6" wafers. The array of nanostructures is designed as 1 mm circular dies consisting of 436 nm wide holes with 545 nm pitch. The circular dies are arranged in an 8 x 8 matrix on the wafers with 7.5 mm pitch. Manufacturing and integration of the PhC reflectors into MEMS is realized by eBeam and nanoimprint lithography (NIL) nanostructure replication on 50 µm thin pre-etched Si membranes combined with further dry and wet etching processes. The fabricated PhC reflectors showed 424 nm wide holes and a pitch of 549 nm with a measured reflectivity above 90 % in the spectral range from 557 to 589 nm and a maximum reflectivity of 99 %.

Miniature dielectric mirrors are useful components for lasers, thin film beam splitters and high quality mirrors in optics. These mirrors usually made from rigid inorganic materials can achieve a reflectance of almost one hundred percent. Being structural components, as soon as fabricated their reflectance and/or bandwidth remains constant. Here it is presented a novel fabrication process of a dielectric mirror based on free standing polymer layers. By applying an electrostatic force between the top and the bottom layers the reflectance can be changed. The large difference between the polymers refractive index and the air allows to achieve a reflectance of more than 85% using only six pairs of nanolayers. Preliminary simulations indicate an actuation speed of less than 1ms. Experimental optical characterization of fabricated structures agrees well with simulation results. Furthermore, structures can be designed to reflect a particular set of colors and/or isolated by using color filters, so a color pixel is fabricated, where the reflectance for each isolated color can be voltage controlled. Potential applications include an active component in a reflective screen display.

We investigate the impact of focused beams on metal-dielectric guided-mode-resonance filters. Under a planewave illumination, these filters show a resonant transmission at an easily tunable wavelength and a good angular acceptance. Although guided-mode resonance is involved, calculations show that under a focused beam the lateral extension of the electromagnetic field inside the waveguide is limited to the width of the beam. We investigate evolution of this lateral extension and the resonant transmission with the size of the beam, as well as the impact of a tilted beam. Guided-mode-resonance filtering under a focused beam is illustrated through the example of a Cassegrain microscope lens. A process for the fabrication of simple metal-dielectric filters is also presented.

High Q/V (quality factor/mode volume) platforms enable simultaneous localization of light in space and time and have enabled enhanced performance metrics in applications such as optical signal processing, photovoltaics, optical sensing and optical trapping. Slotted photonic crystal nanobeams (SPCNs) are one type of high Q/V structure that support mechanical modes in addition to high Q optical modes, opening the door to favorable optomechanical properties. In this work, in-plane excitation of fundamental resonance modes in SPCNs with high optical quality factor and high values of optomechanical coupling strength is investigated towards the realization of a monolithic configuration that is compatible with photonic integrated chips. In-line and side- coupled excitation configurations are studied. Simulations suggest that the number of optical modes supported in the SPCNs and the transmission intensity of light in these modes depend strongly on coupling configuration. For high Q SPCNs, in-line coupling suppresses the fundamental optical mode. Side-coupling supports excitation of the fundamental optical mode, but suppresses even order modes in the cavity.

A novel thin-film single-layer structure based on resonant waveguide gratings (RWGs) allows to engineer selective color filtering and steering of white light. The unit cell of the structure consists of two adjacent finite-length and cross-talking RWGs, where the former acts as in-coupler and the latter acts as out-coupler. The structure is made by only one nano-imprint lithography replication and one thin film layer deposition, making it fully compatible with up-scalable fabrication processes. We characterize a fabricated optical security element designed to work with the flash and the camera of a smartphone in off-axis light steering configuration, where the pattern is revealed only by placing the smartphone in the proper position. Widespread applications are foreseen in a variety of fields, such as multifocal or monochromatic lenses, solar cells, biosensors, security devices and seethrough optical combiners for near-eye displays.

CMOS technology allows a femto Joule energy dissipation per logic operation, if operated at optimal frequency and voltage. However, this value remains orders of magnitude above the theoretical limit predicted by Lan-dauer. In this work, we present a new paradigm for low power computation, based on variable capacitors. Such components can be implemented with existing MEMS technologies. We show how a smooth capacitance modu-lation allows an energy-efficient transfer of information through the circuit. By removing electrical contacts, our method limits the current leakages and the associated energy loss. Therefore, capacitive logic must be able to achieve extremely low power dissipation when driven adiabatically. Contactless capacitive logic also promises a better reliability than systems based on MEMS nanorelays.

The development of selective alkali metal ions sensors in particular is a subject of significant interest. In this respect, the level of blood electrolytes, particularly H⁺, Na⁺, K⁺ and Cl^- , is widely used to monitor aberrant physiologies associated with pulmonary emphysema, acute and chronic renal failure, heart failure, diabetes. The sensors reported in this paper are created by holographic recording of surface relief structures in a self-processing photopolymer material. The structures are functionalized by ionophores dibenzo-18-crown-6 (DC) and tetraethyl 4-tert-butylcalix[4]arene (TBC) in plasticised polyvinyl chloride (PVC) matrix. Interrogation of these structures by light allows indirect measurements of chemical analytes’ concentration in real time. We present results on the optimisation and testing of the holographic sensor. A self-processing acrylamide-based photopolymer was used to fabricate the required photonic structures. The performance of the sensors for detection of K⁺ and Na⁺ was investigated. It was observed that the functionalisation with DC provides a selective response of the devices to K⁺ over Na⁺ and TBC coated surface structures are selectively sensitive to Na⁺. The sensor responds to Na+ within the physiological ranges. Normal levels of Na⁺ and K⁺ in human serum lie within the ranges 135-148mM and 3.5-5.3 mM respectively.

Nanoscale patterning is the key process to manufacture important products such as semiconductor microprocessors and data storage devices. Many studies have shown that it has the potential to revolutionize the functions of a broad range of products for a wide variety of applications in energy, healthcare, civil, defense and security. However, tools for mass production of these devices usually cost tens of million dollars each and are only affordable to the established semiconductor industry. A new method, nominally known as "pattern-on-the- y", that involves scanning an array of optical or electrical probes at high speed to form nanostructures and offers a new low-cost approach for nanoscale additive patterning. In this paper, we report some progress on using this method to pattern self-assembled monolayers (SAMs) on silicon substrate. We also functionalize the substrate with gold nanoparticle based on the SAM to show the feasibility of preparing amphiphilic and multi-functional surfaces.

We report on the site-selective growth of >90% vertical GaAs nanowires (NWs) on Si (111) using self-assisted molecular beam epitaxy. The influences of growth parameters (pre-growth Ga opening time, V/III flux ratio) and processing conditions (reactive ion etching (RIE) and HF etching time) are investigated for different pitch lengths (200- 1000 nm) to achieve vertical NWs. The processing variables determine the removal of the native oxide layer and the contact angle of Ga-droplet inside the patterned hole that are critical to the vertical orientation of the NWs. Pre-growth Ga-opening time is found to be a crucial factor determining the size of the droplet in the patterned hole, while the V/III beam equivalent pressure (BEP) ratio influenced the occupancy of the holes due to the axial growth of NWs being group-V limited.

When mechanically exfoliated two-dimensional (2D) materials are used for device applications, their properties strongly depend on the geometry and number of layers present in the flake. In general, these properties cannot be modified once a device has been fabricated out of an exfoliated flake. In this work we present a novel nano-patterning method for 2D material based devices, Pulsed eBeam Gas Assisted Patterning (PEBGAP), that allows us to fine tune their geometry once the device fabrication steps have been completed.

Nanocellulose is a high value material that has gained increasing attention because of its high strength, stiffness, unique photonic and piezoelectric properties, high stability and uniform structure. One of the factors limiting the potential of nanocellulose and the vast array of potential new products is the ability to produce high-volume quantities of this nano-material. However, recent research has demonstrated that nanocellulose can be efficently produced in large volumes from wood at relatively low cost by the incorporation of ionizing radiation in the process stream. Ionizing radiation causes significant break down of the polysaccharides and leads to the production of potentially useful gaseous products such as H₂ and CO. Ionizing radiation processing remains an open field, ripe for innovation and application. This presentation will review the strong collaboration between the National Institute of Standards and Technology (NIST) and its academic partners pursuing the demonstration of applied ionizing radiation processing to plant materials for the manufacturing and characterization of novel nanomaterials.

All dielectric metasurface of low loss TiO₂ in visible wavelengths was devised forming subwavelength-scale nanostructures. DC-magnetron sputtering of oxygen-reduced TiOx (x<;2) target with reactive oxygen gas made dense amorphous TiO₂ layers of 1.35nm Ra. A 380nm-thick TiO₂ has low extinction coefficient (k) under 1x10^-5, transparency of 98.33% and high refractive index (n) of 2.55 at 485nm wavelength. Highly precise TiO₂ meta-atoms were successfully defined with 100nm-300nm feature size. Phase shift properties of TiO₂ metasurface were measured. Finally, we constructed dielectric metaphotonic platform for various optical devices such as band pass filters, flat lens and beam deflectors in visible ranges.

Optical-electronic Integrated Neural Co-processor takes vital part in optical neural network, which is mainly realized by optical interconnects. Because of the accuracy requirement and long-term goal of integration, optical interconnects should be effective and pint-size. In traditional solutions of optical interconnects, holography built on crystalloid or law of Fresnel diffraction exploited on zone plate was used. However, holographic method cannot meet the efficiency requirement and zone plate is too bulk to make the optical neural unit miniaturization. Thus, this paper aims to find a way to replace holographic method or zone plate with enough diffraction efficiency and smaller size. Metasurfaces are composed of subwavelength-spaced phase shifters at an interface of medium. Metasurfaces allow for unprecedented control of light properties. They also have advanced optical technology of enabling versatile functionalities in a planar structure. In this paper, a nanostructure is presented for optical interconnects. The comparisons of light splitting ability and simulated crosstalk between nanostructure and zone plate are also made.

Low-density foam targets for laser induced shock wave propagation experiments were produced via laser direct writing from polymeric materials. These targets were designed with dimensions of 2.0X0.25X0.3mm with a density of 100mg/cm³ and included a fully polymerized ablation layer, 15μm thick, written contiguously with the low density material in a single fabrication step. We developed a unique protocol in order to assist in the release and harvest of the foam targets from the glass substrate on which they were fabricated. The fabrication process, as well as the assembly and handling of these delicate brittle samples is described in this paper, demonstrating the flexibility, versatility and efficiency of two photon polymerization as fabrication technique that may complement conventional approaches for low density materials fabrication. An ongoing research effort is being conducted in order to reduce to the minimum the content of stitching defects between the target’s building blocks.

Carbon nanotubes (CNTs) have been expected for applications in many future electronic devices. To fabricate CNT structures on substrates, several techniques such as spray coating, spin coating and vacuum filtration have been proposed so far. In this work, we report a very simple and efficient method to deposit CNTs on a glass substrate by only scanning a focused light in CNT dispersion. This fabrication technique can provides a bottom up method for the deposition of CNTs in arbitrary shape on the substrate. We placed the dispersion of single-walled carbon nanotubes (SWCNTs) on a glass substrate. From the back side of the substrate, a laser (λ=975 nm; 100 mW) was focused on the interface between the substrate and the SWCNT dispersion by an oil immersion objective lens (Nikon 100X 1.25NA). Once the focal spot of the light is in focus on the substrate, it began to deposit SWCNTs around the spot (~1 um). Then, the linewidth of the deposition of SWCNTs was approximately 30um, and its electrical conductivity was 12.5 S/cm. We measured the Raman spectrums of the SWCNT dispersion and the deposited SWCNTs. Their G/D ratios were the same value, which indicated that any lattice defects were hardly occurred to SWCNTs in this process. Hence, this method can be useful application for fabrication processes of a variety of CNT devices. We have built the prototype of CNT field-effect transistors. In this presentation, we will show that a collimated light instead of the focused light can be applicable also.

A low contact resistance electrode for p-GaN was obtained using the metallic multi-wall carbon nanotubes (MWCNTs) as the electrode material. The work function of the metallic MWCNTs was confirmed to be 4.84 eV as large as that of Au, Pd and Ni which are generally used for the p-GaN electrode material. Consequently the specific contact resistance was obtained to be as low as 2×10^-3 Ωcm² by optimizing the GaN surface treatment using hydrochloric acid because of the large work function of the MWCNTs. We also characterized the properties of LEDs using the MWCNTs ohmic contact for p-GaN. Low operation voltage and high optical output power was successfully obtained. Threshold voltage was about 2.7 V, and optical output power was about 0.8 W for the 1×1 mm² size LED chip.

Earlier research has sought to utilize the exceptional thermal conductivity of CNTs to produce a heat spreader by bulk cross-linking the CNTs into an interpenetrating network. An isotropic thermal conductivity of 2150 W/m-K was measured in a 5 μm thick MWCNT film which had been subject to argon ion bombardment with an ion energy of 4 keV and a fluence on the order of 10¹⁷ ions/cm² . While energetic ions will randomly bombard the entire CNT network, on occasion, one will strike a junction where two or more CNTs are touching, momentarily disrupting them. CNTs have the remarkable ability to self-heal, and in doing so, the disrupted junction self-heals into a new interpenetrating junction. However, practical heat spreader applications require films at least 100 times thicker than this initial demonstration. To achieve this, substantially higher ion energies and fluence were applied. But rather than forming interpenetrating junctions deeper into the bulk of a CNT thick film, an interesting new form of high aspect ratio structure results, where groups of CNTs are now vertically aligned, even though the original CNT thick film was randomly oriented. There is also a sharp transition at the base of these structures from the new aligned form to the original randomly oriented form. We consider various aspects of ion-induced sputter dynamics coupled to the growth processes of CNTs to account for these new aligned high aspect ratio structures. The role of ion channeling within and between CNTs is also considered.

Graphene rolled-up cylindrical sheets i.e. carbon nanotubes (CNTs) is one of the finest and emerging research area. This paper presents the investigation of induced crosstalk in coupled on-chip multiwalled carbon nanotube (MWCNT) interconnects using finite-difference analysis (FDA) in time-domain i.e. the finite-difference time-domain (FDTD) method. The exceptional properties of versatile MWCNTs profess their candidacy to replace conventional on-chip copper interconnects. Time delay and crosstalk noise have been evaluated for coupled on-chip MWCNT interconnects. With a decrease in CNT length, the obtained results for an MWCNT shows that transmission performance improves as the number of shells increases. It has been observed that the obtained results using the finite-difference time domain (FDTD) technique shows a very close match with the HSPICE simulated results.

Strontium Barium Niobate (SBN) has been known for its highest electro optic coefficient amongst the known photorefractive materials. SBN thin films were prepared using Pulsed Laser Deposition (PLD) technique on the conducting LSCO coated Si Substrate and its tetragonal tungsten bronze structure was confirmed using X-ray diffraction technique. Surface Plasmon Resonance (SPR) technique has been effectively used by exploiting the SBN thin film in Otto configuration using prism coupling technique. The SPR reflectance curves for prism/air-gap/gold/SBN/LSCO/Si system were obtained by varying the applied electric field from 0 to 150kV/cm. A continuous increase in minimum reflectance of SPR curves with increase in the electric field across the SBN thin film has been obtained indicating variation in optical properties of SBN thin film on application of electric field. This increase in reflectance was attributed to the change in propagation constant of wave vector due to the change of optical properties of the film under consideration. The resonance condition changes hence the SPR minimum reflectance angle and position changes.

The ability to convert photons of different wavelength directly into mechanical motion is of significant interest in many energy conversion and reconfigurable technologies. Using few layer 2H-MoS₂ nanosheets, layer by layer process of nanocomposite fabrication, and strain engineering, we demonstrate a reversible and chromatic mechanical response in MoS₂-nanocomposites between 405 nm to 808 nm with large stress release. The chromatic mechanical response originates from the d orbitals and is related to the strength of the direct exciton resonance A and B of the few layer 2HMoS₂ affecting optical absorption and subsequent mechanical response of the nanocomposite. The unique photomechanical response in 2H-MoS₂ based nanocomposites is a result of the rich d electron physics not available to nanocomposites based on sp² bonded graphene and carbon nanotubes, as well as nanocomposite based on metallic nanoparticles. The reversible strain dependent optical absorption suggest applications in broad range of energy conversion technologies.

GaN films have been successfully fabricated using Laser Molecular Beam Epitaxy (LMBE) technique on bare c-plane sapphire substrate and ZnO nanostructures (NS) decorated Si (100) substrates. The ZnO nanostructures were grown on Si (100) substrate using high pressure assisted Pulsed laser deposition technique in inert gas ambience. Discrete nanostructured morphology of ZnO was obtained using the PLD growth on Si substrates. Photoluminescence studies performed on the prepared GaN/Sapphire and GaN/ZnO-NS/Si systems, revealed a significant PL enhancement in case of GaN/ZnO-NS/Si system compared to the former. The hexagonal nucleation sites provided by the ZnO nanostructures strategically enhanced the emission of GaN film grown by Laser MBE Technique at relatively lower temperature of 700°C. The obtained results are attractive for the realization of highly luminescent GaN films on Si substrate for photonic devices.

Optical devices with features exhibiting ultra low reflectivity on the order of 1e-7 specular reflectance and 0.1% hemispherical TIR in the visible spectrum enable unique applications in astronomical research and instruments such as coronagraphs and spectrometers. Nanofabrication technologies have been developed to produce such devices with various shapes and feature dimensions to meet these requirements. Infrared reflection is also suppressed significantly with chosen wafers and processes. Very low levels of specular and scattered light are achievable over a very broad spectral band. We present some of the approaches, challenges and achieved results in producing and characterizing such surfaces and devices currently employed in laboratory testbeds and instruments. The level of blackness achievable in relation to basic material properties such as conductivity and process variables are discussed in detail.

We propose a design for light coupling optimization between an optical fiber and a sub-micrometer waveguide using a subwavelength segmented waveguide taper with subwavelength periodicity. The power coupling and light coupling of the output waveguide are calculated, optimized and compared with other designs and values found in the literature. The optimized tapers has been successfully and efficient designed using evolutionary algorithms based on artificial immune system (AIS), the genetic algorithm (GA) and ant colony optimization (ACO). Power coupling above 75 % have been obtained with the evolutionary algorithms.

It has been well-known that subwavelength metal slits grating structures function as extraordinary optical transmission filters due to excitation of surface plasmon-polaritons. In this work, we show that complex metal-dielectric subwavelength grating structures can also be designed to function as reflection-type optical filters with narrow spectral line-width in the infrared regime. Unlike extraordinary transmission filters, the new reflection optical filters with sharp spectral profiles can be designed within the entire infrared range by adjusting the height and period of the subwavelength grating structure. Detailed analysis has shown that the contrast of refractive indices of two dielectric materials embedded in the metal-dielectric structure is critical for giving sharp reflection spectral profiles.

One problem common to imaging techniques based on coherent light is speckle noise. This phenomenon is caused mostly by random interference of light scattered by rough surfaces. Speckle noise can be avoided by using advanced holographic imaging techniques such as optical scanning holography. A more widely known method is to capture several holograms of the same object and to perform an averaging operation so that the signal to noise ratio can be improved. Several digital filters were also proposed to reduce noise in the numerical reconstruction plane of holograms, even though they usually require finding a compromise between noise reduction and edge preservation. In this study, we used a digital filter based on compressive sensing algorithm. This approach enables to obtain results equivalent to the average of multiple holograms, but only a single hologram is needed.

Filters for speckle reduction are applied on numerical reconstructions of hologram, and not on the hologram itself. Then, optical reconstruction cannot be performed. We propose a method based on direct-binary search (DBS) algorithm to generate binary holograms that can be reconstructed optically after application of a speckle reduction filter. Since the optimization procedure of the DBS algorithm is performed in the image plane, speckle reduction techniques can be applied on the complex hologram and used as a reference to obtain a binary pattern where the speckle noise generated during the recording of the hologram has been filtered.

Vanadium dioxide (VO₂) is a polycrystalline material that exhibits reversible transition from a monoclinic semiconducting phase to a tetragonal metallic phase at 68°C. During this phase transition, both the real part and the imaginary part of the refractive index undergoes a dramatic change. Furthermore, the finite conductivity of the VO₂ in both phases allows for ohmic heating as the source of the temperature change, which circumvents the need for an external heat source. This provide an attractive means for designing switchable optical components such as sub-wavelength polarizers and beam steerers. In this work, VO₂ films were grown by ion-assisted deposition (IAD) using electron beam evaporation on sapphire substrates. Since the VO₂ thin film is difficult to etch, we designed a unique lift-off process to obtain the VO₂ wire grids that is compatible with the high temperature deposition process. Rigorous Coupled Wave Analysis (RCWA) was applied to the wiregrid polarizer to study its polarization properties in the mid-infrared region. The polarizers extinction was modeled at room temperature when the polarizer is at the OFF state and the 68°C when it is at the ON state.

A nano dimensional standard named SIMT100 was designed and fabricated. The standard consists of a tracking area, a step height area, a 1D grating area, and a 2D grating area. All the structures were fabricated with a height of 100 nm in a 3 mm × 3 mm silicon substrate. To calibrate the standard, a white light interference microscope was constructed and integrated to the nano measuring machine (NMM). The height of a 10 μm width step measured by white light interference (WLI) microscope was 100.2 nm with a standard deviation of 0.41 nm. Due to low lateral resolution of the optical microscope, a metrological atomic force microscope (AFM) was used to measure the 1D and 2D gratings. The period length of the 1D grating evaluated by using the fast Fourier transform (FFT) method was 2999.7 nm with a standard deviation of 0.36 nm. The FFT method was also expended for evaluation of the 2D grating. The calibrated value of 2D grating along the x- and y-axis were 3001.2 and 3000.7 nm with standard deviations of 0.73 and 0.64 nm, respectively. All the measurement results are traceable because the data was recorded by three stabilized laser interferometers embedded in the NMM.

In order to achieve the use of pure water in the developable process of extreme-ultraviolet and electron beam lithography, instead of conventionally used tetramethylammonium hydroxide and organic solvents, a water developable resist material was designed and developed. The water-developable resist material was derived from woody biomass with beta-linked disaccharide unit for environmental affair, safety, easiness of handling, and health of the working people. 80 nm dense line patterning images with exposure dose of 22 μC/cm² and CF₄ etching selectivity of 1.8 with hardmask layer were provided by specific process conditions. The approach of our water-developable resist material will be one of the most promising technologies ready to be investigated into production of medical device applications.

The feasibility of applying ultraviolet light-emitting diodes (UV-LED’s) as triggering sources of photo-catalyst based on titanium dioxide (TiO₂) nano-coating specifically for water-cleaning process in an aquaponics system was designed and proposed. The aquaponics system is a modern farming system to integrate aquaculture and hydroponics into a single system to establish an environmental-friendly and lower-cost method for farming fish and vegetable all together in urban area. Water treatment in an aquaponics system is crucial to avoid mutual contamination. we proposed a modularized watercleaning device composed of all commercially available components and parts to eliminate organic contaminants by using UV-LED’s for TiO₂ photo-catalyst reaction. This water-cleaning module consisted of two coaxial hollowed cylindrical pipes can be submerged completely in water for water treatment and cooling UV-LED’s. The temperature of the UV-LED after proper thermal management can be reduced about 16% to maintain the optimal operation condition. Our preliminary experimental result by using Methylene Blue solution to simulate organic contaminants indicated that TiO₂ photo-catalyst triggered by UV-LED’s can effectively decompose organic compound and decolor Methylene Blue solution.

A cellulose-based gas permeable mold having thermal crosslinking group for nanoimprint lithography has been developed to prevent transcriptional defects by volatile solvents from nanoimprinting materials. 3 wt.% of thermal initiator was required for producing the cellulose-based gas permeable mold. The void on 10 μm line structure of imprinted UV crosslinked resin with acetone as volatile solvents in nanoimprint lithography process using non-gas permeable mold was significantly removed using the cellulose-based gas permeable mold due to its high oxygen gas permeability. The cellulosebased gas permeable mold allows the employment of solvent including imprinting materials such as compounds and alloy particle.

Passivated contacts can be used to reduce metal-induced recombination for higher energy conversion efficiency for silicon solar cells, and are obtained increasing attentions by PV industries in recent years. The reported thicknesses of passivated contact layers are mostly within tens of nanometer range, and the corresponding metallization methods are realized mainly by plating/evaporation technology. This high cost metallization cannot compete with the screen printing technology, and may affect its market potential comparing with the presently dominant solar cell technology. Very few works have been reported on screen printing metallization on passivated contact solar cells. Hence, there is a rising demand to realize screen printing metallization technology on this topic. In this work, we investigate applying screen printing metallization pastes on poly-silicon passivated contacts. The critical challenge for us is to build low contact resistance that can be competitive to standard technology while restricting the paste penetrations within the thin nano-scale passivated contact layers. The contact resistivity of 1.1mohm-cm² and the open circuit voltages > 660mV are achieved, and the most appropriate thickness range is estimated to be around 80~150nm.

A chemical cross-linked transparent film was got by a silicon compound to crystalline cellulose. Temperature dependency for the elasticity modulus of a provided film was measured. The shear elastic modulus was obtained the value of 2 x 10⁶ [Pa] at room temperature. The sample decreases in 190 [deg. C] for the elasticity modulus at the room temperature as 60%, but approximately 10% recover when temperature rises up to 200 [deg. C] or more.

Silicone elastomers ( polydimethylsiloxane _ PDMS) are widely used in the field of imprint lithography and microcontactprinting (μCP). When performing microcontactprinting, the mechanical properties of the PCMS as a base material have a great influence on the performance of the device. Cellulose nanofibers having features of high strength, high elasticity and low coefficient of linear expansion have attracted attention in recent years due to their characteristics. Therefore, three types of crystalline cellulose having different molecular weights were added to PDMS to prepare a composite material, and dynamic viscoelasticity was measured using a rheometer. The PDMS with the highest molecular weight crystalline cellulose added exhibited smaller storage modulus than PDMS with other molecular weight added in all temperature ranges. Furthermore, when comparing PDMS to which crystalline cellulose was added and PDMS which is not added, the storage modulus of PDMS to which cellulose was added in the low temperature region was higher than that of PDMS to which it was not added, but it was reversed in the high temperature region It was a result. When used in a low temperature range (less than 150 ° C.), it can be said that cellulose can function as a reinforcing material for PDMS.

In this project, SiC based MEMS capacitive microphone was developed for detecting leaked gas in extremely harsh environment such as coal mines and petroleum processing plants via ultrasonic detection. The MEMS capacitive microphone consists of two parallel plates; top plate (movable diaphragm) and bottom (fixed) plate, which separated by an air gap. While, the vent holes were fabricated on the back plate to release trapped air and reduce damping. In order to withstand high temperature and pressure, a 1.0 μm thick SiC diaphragm was utilized as the top membrane. The developed SiC could withstand a temperature up to 1400°C. Moreover, the 3 μm air gap is invented between the top membrane and the bottom plate via wafer bonding. COMSOL Multiphysics simulation software was used for design optimization. Various diaphragms with sizes of 600 μm², 700 μm², 800 μm², 900 μm² and 1000 μm² are loaded with external pressure. From this analysis, it was observed that SiC microphone with diaphragm width of 1000 μm² produced optimal surface vibrations, with first-mode resonant frequency of approximately 36 kHz. The maximum deflection value at resonant frequency is less than the air gap thickness of 8 mu;m, thus eliminating the possibility of shortage between plates during operation. As summary, the designed SiC capacitive microphone has high potential and it is suitable to be applied in ultrasonic gas leaking detection in harsh environment.

Sulfurization of a Mo layer is one of the most used methods for preparation of thin Mo_S2 films. In the method, a sulfur powder and Mo covered substrate are placed in different positions within a furnace, and heated separately. This requires a furnace having at least two zones. Here, we present a simplified version of the method where a one-zone tube furnace was used. A molybdenum film on a substrate and a sulfur powder were placed in the center of the furnace and heated at temperatures above 800°C. Mo films transform into Mo_S2 in vapors of sulphur at high temperatures. As-prepared films were characterized by number of techniques including X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman, Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS). It appears that one-zone sulfurization, with just one annealing temperature used, is a suitable method for fabrication of Mo_S2 thin films. This method is fast, cheap and easy to scale up.

We couple He-Ne laser into a tapered fiber tip made of single-mode fiber. To explore spatial filtering mechanism, we observe its output-light diffraction pattern variation by displacing the imaging lens or changing the tapering ratio.

Zirconia (ZrO₂)-based ceramics are preferred due to their advanced mechanical properties such as high-fracture toughness and bulk modulus, corrosion resistance, high dielectric constant, chemical inertness, low chemical conductivity and biocompatibility. The medical prosthesis components made from ZrO₂ oxides present a very good biocompatibility as well as especially mechanical properties. In order to ensure implant safety of these prostheses, wide ranges of examinations based on nondestructive testing are imperative for these medical implants. In this study, we aim to emphasize the improvement of Zr-based ceramics properties as a function of addition of Ce ions in the structure of the original ceramics. The substitution of the Zr with Ce in the Zr_1-xCexO₂ compounds, where x = 0.0–0.17, leads to a change of the phase composition, a gradual transition from the monoclinic to tetragonal structure, at room temperature. The structural investigations proposed in this paper are based on X-ray and neutron diffraction in order to establish a first indication of the variation of the phase composition and the structural parameters, as well as micro-hardness measurements and nondestructive evaluations in order to establish a correlation between the structural parameters and mechanical properties of the samples. These ranges of tests are imperative in order to ensure the safety and reliability of these composite materials, which are widely used as hip-implants or dental implants/coatings. In combination of Resonant Ultrasound Spectroscopy, which makes use of the resonance frequencies corresponding to the normal vibrational modes of a solid in order to evaluate the elastic constants of the materials, we emphasize a unique approach on evaluating the physical properties of these ceramics, which could help in advancing the understanding of properties and applications in medical fields.

Optical modulators are essential components for optical communication systems. In this paper we introduce and discuss the concept of designer metamaterials in the context of graphene-based optical modulators. This is a very powerful tool, which enables device design with ultra-compact footprint, low energy consumption, and high speed. As an example, we design an integrated nano-photonic optical modulator. For a target modulation performance, i.e. modulation depth and insertion loss levels, we show that the designer metamaterial device footprint can be reduced with respect to what is possible in ridge waveguide approaches.

Advanced nano-imprint lithography appears as a simple, cost reduction in manufacturing, fast operation, develop-less patterning application compatible with conventional pattern transfer techniques such as ultraviolet and electron beam lithography. However, defects generated in nano-imprint lithography present challenges that must be resolved in order to mass-produce advanced devices. The nano-imprint lithography requires the clean separation of a quartz template from a resist material, and the force required to create this separation must be minimized to prevent the resist pattern collapse and defects. This procedure is proven to be suitable for material design and the process conditions of organic-inorganic hybrid resist materials on photo-reactive underlayer material for the defect reduction by mold contamination when the mold was removed from the organic-inorganic hybrid resist materials after ultraviolet irradiation. The developed organic-inorganic hybrid resist material with ultraviolet crosslinking groups produced high resolutions nano-patterning of 50 nm line and excellent etch properties for semiconductor memory, MEMS, NEMS, biosensors, and medical devices.

In this work, we show how the hysteretic behaviour of resonant tunnelling diodes (RTDs) can be exploited for new functionalities. In particular, the RTDs exhibit a stochastic 2-state switching mechanism that could be useful for random number generation and cryptographic applications. This behaviour can be scaled to N-bit switching, by connecting various RTDs in series. The InGaAs/AlAs RTDs used in our experiments display very sharp negative differential resistance (NDR) peaks at room temperature which show hysteresis cycles that, rather than having a fixed switching threshold, show a probability distribution about a central value. We propose to use this intrinsic uncertainty emerging from the quantum nature of the RTDs as a source of randomness. We show that a combination of two RTDs in series results in devices with three-state outputs and discuss the possibility of scaling to N-state devices by subsequent series connections of RTDs, which we demonstrate for the up to the 4-state case.

In this work, we suggest using that the intrinsic uncertainty in the conduction paths of resonant tunnelling diodes can behave as a source of randomness that can be integrated into current electronics to produce on-chip true random number generators. The N-shaped I-V characteristic of RTDs results in a two-level random voltage output when driven with current pulse trains. Electrical characterisation and randomness testing of the devices was conducted in order to determine the validity of the true randomness assumption. Based on the results obtained for the single RTD case, we suggest the possibility of using multi-well devices to generate N-state random switching devices for their use in random number generation or multi-valued logic devices.

Two-photon polymerization (2PP), a 3D nano to microscale additive manufacturing process, is being used for the first time to fabricate small custom experimental packages (“targets”) to support laser-driven high-energy-density (HED) physics research. Of particular interest is the use of 2PP to deterministically print low-density, low atomic-number (CHO) polymer matrices (“foams”) at millimeter scale with sub-micrometer resolution. Deformation during development and drying of the foam structures remains a challenge when using certain commercial photo-resins; here we compare use of acrylic resins IP-S and IP-Dip. The mechanical strength of polymeric beam and foam structures is examined particularly the degree of deformation that occurs during the development and drying processes. The magnitude of the shrinkage in the two resins in quantified by printing sample structures and by use of FEA to simulate the deformation. Capillary drying forces are shown to be small and likely below the elastic limit of the core foam structure. In contrast the substantial shrinkage in IP-Dip (~5-10%) cause large shear stresses and associated plastic deformation particularly near constrained boundaries such as the substrate and locations with sharp density variation. The inherent weakness of stitching boundaries is also evident and in certain cases can lead to delamination. Use of IP-S shows marked reduction in deformation with a minor loss of print resolution