Nano Fabrication

In this article, a new mechanism so-called wet cluster engulfment and the related formula were proposed to predict the critical solidification velocity for nanoparticles engulfment by a solidification front. According to the mechanism, the most important issue in the engulfing of the nanoparticles is the aggregation of nanoparticles, i.e. the formation of wet clusters in front of solidifying phase. In fact, local clustering of nanoparticles created highly viscous zones in the vicinity of the solidification front so that the nanoparticles and the liquid-filled spaces between them move as a unified mass. Thus, the van der Waals and drag forces between a nanoparticles cluster and the solidification front were calculated analytically. The new formulae were derived for the critical solidification velocity and critical diameter of the clusters as a function of the melt viscosity, the nanoparticle size, the cluster size, and the nanoparticle volume concentration inside the cluster. The theoretical results showed that the new model predicted more accurate values for the critical velocity than the earlier models. The proposed model can explain the formation of nanoparticle-rich zones and zones with a low concentration of nanoparticles in the microstructure of the nanocomposites produced via casting.

Heterogeneous photocatalysis is a promising technology especially for environmental remediation. Despite more than a decade of worldwide research in developing photocatalytic efficiency improving techniques, many questions regarding the large scale application of photocatalytic reactors still remain unanswered. Recently, improving the photocatalytic efficiency has gained scientific attention because it might lead to more economical and robust photocatalytic operation for environmental remediation. In this review, fundamental and comprehensive assessments of the photocatalytic concepts and their applications for environmental remediation are reviewed. The existing challenges and strategies to improve the photocatalytic efficiency are discussed. Further, recent developments and future research prospects on photocatalytic systems for environmental applications are also addressed.

International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access journal, addresses the impacts and challenges of Physics. The journal documents practical and theoretical results which make a fundamental contribution for the development of Physics.

International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access
journal, addresses the impacts and challenges of Physics. The journal documents practical and
theoretical results which make a fundamental contribution for the development of Physics.

This article provides an overview of the state-of-the-art chemistry and processing technologies for silicon nitride and silicon nitride-rich films, i.e., silicon nitride with C inclusion, both in hydrogenated (SiN x :H and SiN x :H(C)) and non-hydrogenated (SiN x and SiN x (C)) forms. The emphasis is on emerging trends and innovations in these SiN x material system technologies, with focus on Si and N source chemistries and thin film growth processes, including their primary effects on resulting film properties. It also illustrates that SiN x and its SiN x (C) derivative are the focus of an ever-growing research and manufacturing interest and that their potential usages are expanding into new technological areas.

Advancements in electronics research triggered a vision of a more connected world, touching new unprecedented fields to improve the quality of our lives. This vision has been fueled by electronic giants showcasing flexible displays for the first time in consumer electronics symposiums. Since then, the scientific and research communities partook on exploring possibilities for making flexible electronics. Decades of research have revealed many routes to flexible electronics, lots of opportunities and challenges. In this work, we focus on our contributions towards realizing a complimentary approach to flexible inorganic high performance electronic memories on silicon. This approach provides a straight forward method for capitalizing on the existing well-established semiconductor infrastructure, standard processes and procedures, and collective knowledge. Ultimately, we focus on understanding the reliability and functionality anomalies in flexible electronics and flexible solid state memory built using the flexible silicon platform. The results of the presented studies show that: (i) flexible devices fabricated using etch-protect-release approach (with trenches included in the active area) exhibit ~19% lower safe operating voltage compared to their bulk counterparts, (ii) they can withstand prolonged bending duration (static stress) but are prone to failure under dynamic stress as in repeated bending and re-flattening, (iii) flexible 3D FinFETs exhibit ~10% variation in key properties when exposed to out-of-plane bending stress and out-of-plane stress does not resemble the well-studied in-plane stress used in strain engineering, (iv) resistive memories can be achieved on flexible silicon and their basic resistive property is preserved but other memory functionalities (retention, endurance, speed, memory window) requires further investigations, (v) flexible silicon based PZT ferroelectric capacitors exhibit record polarization, capacitance, and endurance (1 billion write-erase cycles) values for flexible FeRAMs, uncompromised retention ability under varying dynamic stress, and a minimum bending radius of 5 mm, and (vi) the combined effect of 225 °C, 260 MPa tensile stress, 55% humidity under ambient conditions (21% oxygen), led to 48% reduction in switching coercive fields, 45% reduction in remnant polarization, an expected increase of 22% in relative permittivity and normalized capacitance, and reduced memory window (20% difference between switching and non-switching currents at 225 °C).

Highly crystalline TiO2 nanostructures were prepared through a facile inorganic acid-assisted hydrothermal treatment of hexagonal-structured assemblies of nanocrystalline titiania templated by cetyltrimethylammonium bromide (Hex-ncTiO2/CTAB Nanoskeleton) as starting materials. All samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The influence of hydrochloric acid concentration on the morphology, crystalline and the formation of the nanostructures were investigated. We found that the morphology and crystalline phase strongly depended on the hydrochloric acid concentrations. More importantly, crystalline phase was closely related to the morphology of TiO2 nanostructure. Nanoparticles were polycrystalline anatase phase, and aligned nanorods were single crystalline rutile phase. Possible formation mechanisms of TiO2 nanostructures with various crystalline phases and morphologies were proposed.

The dynamic behavior of sandwich cantilever beam has not been extensively investigated, the application of cantilevers is found extensively in structural elements, supporting device for motors or engines and construction of bridges. Dynamic stresses will be induced on beams hence it is important to know the natural frequencies of beam-mass system. Present work involves comparison of dynamic behavior of aluminum and steel cantilever beam with sandwich beam of aluminum and steel both analytical and numerical analysis. The natural frequency calculated by using equations and it has been validated numerically and variation of 1 to 5 % noted difference between numerical and analytical analysis.

In this paper, we present an ultra-fast and high-contrast optical shutter with applications in atomic clock assemblies, integrated photonic systems, communication hardware, etc. The shutter design exploits the total light absorption phenomenon in a thin phase change (PC) material placed over a metal layer. The shutter switches between ON and OFF states by changing PC material phase and thus its refractive index. The PC material used in this work is Germanium Telluride (GeTe), a group IV-VI chalcogenide compound, which exhibits good optical contrast when switching from amorphous to crystalline state and vice versa. The stable phase changing behavior and reliability of GeTe and GeSbTe (GST) have been verified in optical memories and RF switches. Here, GeTe is used as it has a lower extinction coefficient in near-IR regions compared to GST. GeTe can be thermally transitioned between two phases by applying electrical pulses to an integrated heater. The memory behavior of GeTe results in zero static power consumption which is useful in applications requiring long time periods between switching activities. We previously demonstrated a meta-surface employing GeTe in sub-wavelength slits with >14 dB isolation at 1.5 μm by exciting the surface plasmon polariton and localized slit resonances. In this work, strong interference effects in a thin layer of GeTe over a gold mirror result in near total light absorption of up to 40 dB (21 dB measured) in the amorphous phase of the shutter at 780 nm with much less fabrication complexity. The optical loss at the shutter ON state is less than 1.5 dB. A nickel chrome (NiCr) heater provides the Joule heating energy required to achieve the crystallographic phase change. The measured switching speed is 2 μs.

This questionnaire is about getting a Fab lab (fabrication laboratory) for students of applied arts college with all it's departments and faculty staff , for any individuals to do a personal projects FabLabs are open high-tech workshops where individuals have the opportunity to develop an produce custom-made things which are not accessible by conventional industrial scale technologies (Knips et al., 2014) FabLabs are organized in a global network of local labs, enabling invention by providing access to tools for rapid digital fabrication (FabFoundation, 2013). Fab labs offer the possibility of digital fabrication and rapid prototyping (especially additive manufacturing) for projects in the fields of science, education and sustainable development (ICTPScientificFabLab, 2014). The fabrication laboratory supports students and faculty in the exploration and investigation of material research including wood, metals, plastics and concrete. The Key principles used at fablabs are Do-It-Yourself (DIY) and Do-It-With-Others (DIWO) implemented by the users who actively explore contents, technologies and possibilities of the Lab themselves and collaborate/share with their peers. A fablab is per definition an open place for everyone: youth, students, researchers,entrepreneurs, startups, small & medium enterprises and university faculty. please see  the link https://goo.gl/forms/QRqPscRuXD6v9sxe2

Spin-on-Carbon (SoC) hardmasks are an increasingly key component of the microchip fabrication process. Progress in lithographic resolution has made the adoption of extremely thin photoresist films necessary for the fabrication of “1x nanometre” linewidth structures to prevent issues such as resist collapse during development. While there are resists with high etch durability, ultimately etch depth is limited by resist thickness. A possible solution is the use of a multilayer etch stack. This allows for considerable increase in aspect ratio. For the organic hard mask base layer, a carbon-rich material is preferred as carbon possesses a high etch resistance in silicon plasma etch processes. A thin silicon topcoat deposited on the carbon film can be patterned with a thin photoresist film without feature collapse, and the pattern transferred to the underlying carbon film by oxygen plasma. This produces high aspect ratio carbon structures suitable for substrate etching. In terms of manufacturability it is beneficial to spin coat the carbon layer instead of using chemical vapor deposition, but the presence of carbon-hydrogen bonds in typical spin-on-carbon leads to line wiggling during the etch (a significant problem at smaller feature sizes). We have developed a fullerene based SoC and reported on material characterization. The materials low Ohnishi number provides high etch durability and the low hydrogen level allows for high resolution etching without wiggling. Here recent advances in material development and work towards commercialization of the materials are presented and the use of the materials in etch stacks is demonstrated.

Surface-patterned ZnO thin films were fabricated by direct imprinting on ZnO sol and subsequent annealing process. The polymer-based ZnO sols were deposited on various substrates for the nanoimprint lithography and converted to surface-patterned ZnO gel films during the thermal curing nanoimprint process. Finally, crystalline ZnO films were obtained by subsequent annealing of the patterned ZnO gel films. The optical characterization indicates that the surface patterning of ZnO thin films can lead to an enhanced transmittance. Large-scale ZnO thin films with different patterns can be fabricated by various easy-made ordered templates using this combination of sol–gel and nanoimprint lithography techniques.

International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access journal, addresses the impacts and challenges of Physics. The journal documents practical and theoretical results which make a fundamental contribution for the development of Physics.

In this project we design and fabricate a hyperbolic metamaterials-based narrowband notch filter for the mid-
wave infrared regime with an angle-of-incidence independent center-wavelength for TM polarized incident light.
To achieve angle of incidence independence, a subwavelength sized array of copper wires is inserted in a vertical
orientation and permeates the three middle layers of the seven layer Bragg stack filer. Analysis using Maxwell-
Garnett theory and full-wave electromagnetic modeling, and the fabrication progress to date are presented.
Narrowband notch filters have applications in optical communications systems, and remote sensors such as
hyperspectral and multi-spectral sensing and imaging.

Diamond is a unique material with robust mechanical properties, the electrical and the optical properties of the thin film diamond can be altered as they are deposited using microwave plasma enhanced chemical vapor deposition (MPCVD) method. The thin film diamond can be used both as optical window for certain wavelengths of light and as a reflector, based on the thickness and the deposition parameters of the thin film diamond. In this paper, we are illustrating a 1 µm thin film diamond that we were able to deposit, pattern and etch selectively using standard microfabrication techniques. This patterning of diamond film allows us to create 3D structures using single crystal diamond.

Understanding and measuring the magnetic properties of an individual nanowire and their relationship
with crystalline structure and geometry are of scientific and technological great interest. In this work, we
report the localized study of the magnetic flux distribution and the undisturbed magnetization of a single
ferromagnetic nanowire that poses a bar-code like structure using off-axis electron holography (EH)
under Lorentz conditions. The nanowires were grown by template-assisted electrodeposition, using AAO
templates. Electron holography allows the visualization of the magnetic flux distribution within and
surroundings as well as its quantification. The magnetic analysis performed at individual nanowires was
correlated with the chemical composition and crystalline orientation of the nanowires.

"This invention relates to methods for bonding substrates, and in particular, bonding of semiconductor and/or semiconductor oxide and nitride wafers.

Abstract: Substrates may be bonded according to a method comprising contacting a first bonding surface of a first substrate with a second bonding surface of a second substrate to form an assembly; and compressing the assembly in the presence of an oxidizing atmosphere under suitable conditions to form a bonding layer between the first and second surfaces, wherein the first bonding surface comprises a polarized surface layer; the second bonding surface comprises a hydrophilic surface layer; the first and second bonding surfaces are different. ...

BACKGROUND

The long-term reliability of multicomponent devices such as bio-sensors and solar cells is at least in part determined by the robustness of the bonding methods used to hold the devices together. Typically, epoxy bonding methods are used to prepare such devices, but suffer from the limitations of limited longevity (10 years) as well as poor thermal matching between components which can lead to internal stresses and ultimately bonding failure. Implantable bio-sensor devices need to be hermetically sealed in a saline environment such as a human or an animal body for the lifetime of the implant.

As many biosensors and solar cells are typically based on silica wafers (borosilicate, alpha-quartz, etc.) and Si(100) wafers, there exists a need in the art for improved methods for bonding the same together. In particular, there exists a need for methods which can provide hermetically sealed devices which may be implanted into the human body. Additionally, there exist needs to improve the temperature and pressure requirements of bonding for such applications. There is also a need to improve the bonding between a broader range of materials for such applications.

SUMMARY

OF THE INVENTION
Accordingly, in a first aspect, the invention provides methods for bonding substrates comprising contacting a first surface of a first substrate with a second surface of a second substrate to form an assembly; and compressing the assembly in the presence of an oxidizing atmosphere under suitable conditions to form a bonding layer between the first and second surfaces, wherein the first surface comprises a polarized surface layer; the second surface comprises a hydrophilic surface layer; the first and second surfaces are different.

In another aspect, the invention provides methods for bonding substrates comprising contacting a first bonding surface comprising O2H2Si(1×1)(100) of a first substrate comprising Si with a second bonding surface of a second substrate comprising a silicate to form an assembly; and compressing the assembly in the presence of an oxidizing atmosphere under suitable conditions to form a bonding layer between the first and second bonding surfaces.

In another aspect, the invention provides methods for bonding substrates comprising contacting a first bonding surface comprising hydroxy-terminated silica of a first substrate comprising a silicate with a second bonding surface comprising SiOx, where 0<x≦2, of a second substrate comprising a silicate to form an assembly; and compressing the assembly in the presence of an oxidizing atmosphere under suitable conditions to form a bonding layer between the first and second bonding surfaces.

In a second aspect, the invention provides the bonded substrates formed according to the first aspect of the invention.

In a third aspect, the invention provides implantable medical devices comprising a bonded substrate of the second aspect of the invention.

In a fourth aspect, the invention provides solar cells comprising a bonded substrate of the second aspect of the invention."

The importance of applying the (physical, mechanical or chemical) gradient for the development of porous scaffolds is undeniable in tissue engineering. Gradient scaffolds enable us to engineer heterogeneous interfacial tissues, to mimic the natural microenvironment of cells, Extra Cellular Matrix (ECM) alignment and clustering the cells. Therefore, they can properly realize the biomimetic approach. Such scaffolds are suitable to create functional tissues through the incorporation of physical and chemical signal gradients. Additionally, using the gradient structures, high throughput screening of cell-scaffold interactions becomes possible for optimization of scaffold design parameters and prevention of errors during the experiments. Thus, in this chapter, we aim to first introduce different types of gradients and then discuss the production techniques of the gradient scaffolds.

Three different thicknesses (50, 150 and 500 nm) Zn-doped polyvinyl alcohol (PVA) was deposited on n-4H-SiC wafer as interlayer by electrospinning method and so, Au/(Zn-doped PVA)/n-4H-SiC metal–polymer–semiconductor structures were fabricated. The thickness effect of Zn-doped PVA on the dielectric constant (ε), dielectric loss (ε), loss-tangent (tan δ), real and imaginary parts of electric modulus (M and M) and ac electrical conductivity (σ ac) of them were analysed and compared using experimental capacitance (C) and conductance (G/ω) data in the frequency range of 1–500 kHz at room temperature. According to these results, the values of ε and ε decrease with increasing frequency almost exponentially, σ ac increases especially, at high frequencies. The M and M values were obtained from the ε and ε data and the M and M vs. f plots were drawn for these structures. While the values of ε , ε and tan δ increase with increasing interlayer thickness, the values of M and M decrease with increasing interlayer thickness. The double logarithmic σ ac vs. f plots for each structure have two distinct linear regimes with different slopes, which correspond to low and high frequencies, respectively, and it is prominent that there exist two different conduction mechanisms. Obtained results were found as a strong function of frequency and interlayer thickness.

International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access journal, addresses the impacts and challenges of Physics. The journal documents practical and theoretical results which make a fundamental contribution for the development of Physics. This journal aims to bring together researchers and practitioners in all Physics aspects, including (but not limited to):

Single walled carbon nanotube FETs (CNTFETs) are the hotbed of research owing to their unique geometric, electrical and mechanical properties which makes them suitable for future nano-electrical applications. This paper explores the various techniques used for controlled positioning of CNTs and the factors which influence them.

Abstract short (short description) Common imaging metrology (Litho Metrology, Defect Metro metrology, Optical inspection etc..) characterized by high level of specialization and optimization for certain measurement condition and requirements. But the process of measurement produce enormous amount of information in the form of the image taken during PR and PM. Significant amount of the information just wasted. The question is could we use this additional information encapsulated in image itself as mean of control over the process. This project purpose is to show the new approach for metrology - decision making conclusion based not just on plain X/Y measurement, but on image itself.
Project long description - free style, with/without charts/pictures etc. In order to apprehend and use the vast amount of information, common measurement practices embedded in SEM/Optical tool algorithms are very limited. The need for advanced Image Processing set of functions is obvious. Due to the fact that it is impossible to create additional IP function in embedded environment without manufacturer interruption much easier approach is to store images acquired during PR and PM and run the set of IP functions over. For example Litho Metrology has wide spectrum of measurement algorithms associated with litho tool parameters (line/space width, via/contact diameter, LER). Pattern recognition in turn as previous step for measurement also tweaked up to recognize common lithography features and create stable output to control lithography process. And the key output parameter is the standard CD's measurement. As example we could process the PR and PM images in certain way to compare them POR images, thus creating binary (good vs bad) control over the process which is independent from X/Y measurement control and will be able to detect non litho issues/defects.
                                       
Proposed system created in the form of framework to support basic requirements for Fab automated tool: User tracing and association, Tool communication, Alarm and Warning interface, Mail communication, Template library, Local SPC, Databases and includes National Instruments Vision Build interface.
Project status: Depicted configuration active and working
Conclusion and expected gain: Totally new approach, last TFs show huge possibility for inline monitoring for non trivial process issues.

The hybrid structure of Fe2O3 nanoparti-
cles/TiO2 nanofibers (NFs), combines the merits of
large surface areas of TiO2 NFs and absorption in
ultraviolet light–visible light range. This structure can
be used for many applications such as photoelectro-
chemical water splitting and photo-catalysis. Here, a
sol-flame method is used for depositing Fe2O3 on TiO2
NFs that were prepared by hydrothermal on Ti sheets.
The obtained materials were characterized by XRD,
SEM, UV/Vis diffuse reflectance, Raman, and XPS.
The results revealed the formation of rutile and anatase
crystalline phases together with Fe2O3. This process
moves the absorption threshold of TiO2 NFs support
into visible spectrum range and enhances the photo-
current in comparison to bare TiO2 NFs, although no
hole scavenger was used. The impedance measure-
ment at low and high frequencies revealed an increase
in series resistance and a decrease in resistance of
charge transfer with sol-flame treatment time. A
mechanism for explaining the charge transfer in these
TiO2 NFs decorated with Fe2O3 nanoparticles was
proposed.

Given the upsurge of new technologies based on nanomaterials, the development of sustainable methods
to obtain functional nanostructures has become an imperative task. In this matter, several recent
researches have shown that the biodegradable natural antioxidants of several plant extracts can be used
simultaneously as reducing and stabilizing agents in the wet chemical synthesis of metallic nanoparticles,
opening new opportunities to design greener synthesis. However, the challenge of these new techniques
is to produce stable colloidal nanoparticles with controlled particle uniformity, size, shape and
aggregation state, in similar manner than the well-established synthetic methods. In the present work,
colloidal metallic silver nanoparticles have been synthesized using silver nitrate and extracts of Illicium
verum (star anise) seeds at room temperature in a facile one-step procedure. The resulting products were
colloidal suspensions of two populations of silver nanoparticles, one of them with particle sizes of few
nanometers and the other with particles of tens of nm. Strikingly, the variation of the AgNO
/extract
weight ratio in the reaction medium yielded to the variation of the spatial distribution of the nanoparticles:
high AgNO
/extract concentration ratios yielded to randomly dispersed particles, whereas for lower
AgNO
3
3
/extract ratios, the biggest particles appeared coated with the finest nanoparticles. This biosynthesized
colloidal system, with controlled particle aggregation states, presents plasmonic and SERS properties
with potential applications in molecular sensors and nanophotonic devices.

In this paper, the fabrication and characterisation processes of both boron doped and undoped barium stabilised bismuth cobalt oxide nanocrystalline ceramic powders using polymeric precursor were reported. Obtained boron doped barium stabilised bismuth cobalt oxide nanocrystalline ceramic powders, which have been synthesised by polymeric precursor technique at temperatures below 900°C and at atmospheric condition, were characterised by X-ray diffraction, Fourier transform infrared and scanning electron microscopy techniques. According to X-ray results, fcc and bcc phases coexist in the samples of the nanocrystalline ceramic powders. Crystallite sizes for body centred cubic structure were calculated using Scherrer equation for both boron doped and undoped samples. In addition, lattice parameters were calculated for all samples.

We present a novel post-release stress-engineering process that can provide out-of-plane curvature to initially planar MEMS structures. This process uses a layer of evaporated Chromium (Cr) with intrinsic compressive stress to provide the required curvature. The stressor layer is applied post-release, and is patterned using shadow masks fabricated in-situ as part of the surface micromachining fabrication process. The masks can be reconfigured to provide variable stressor layer coverage of the underlying structures without the use of photolithography. A model is presented that encompasses the increase in deflection, and thus non-uniform chromium coverage, during the stress-engineering of released structures.

Stress Engineering is a method that induces curvature in initially planar micromachined structures by deposition of a stressor layer. Post-release stress engineering occurs when the stressor layer is deposited and patterned after the release of the underlying microstructures. In this paper we present a post-release stress engineering process which patterns the stressor layer without the use of a photolithography step through a set of in-situ fabricated reconfigurable shadow masks. These shadow masks are made by the same surface micromachining fabrication process as the stress-engineered structures, and their self-reconfiguration enables precise definition of the evaporated stressor layer. The alignment of the masks is automated using surface-micromachined actuators called scratch drives Actuators (SDAs) which move the shadow masks to the desired configuration. We present both theoretical and experimental results showing the viability of the new post-release stress-engineering method. In particular, application of self-reconfigurable shadow masks to developing a suite of field-programmable MicroStressBots (i.e. MicroStressBots where the steering arms can be programmed after most of the micromachining process) is presented.

The use of plant products as nutritional food and therapeutic agents is immemorial and intimately linked to the human life since its origin. Also, the tanning action of plant extracts has been hugely exploited to transform animal skins into leather from ancient times to present. However, the exploitation of the potential applications of plant biomolecules in some of the modern technologies is rather now emerging. In fact, the power antioxidant, reducing and biological activities of the plant metabolites together their chelating and their biodegradable properties, make the plant-derived natural products unique raw materials to design new sustainable approaches to prepare promising hybrid formulations and composites at the nanometer scale for innovative diagnostic and therapeutic procedures and nanotechnology applications. In the present contribution, some recent advances and present challenges in this topic are briefly discussed.