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Silicon Nanowire (SiNW) based reconfigurable fieldeffect transistors (RFETs) provide an additional gate terminal called the program gate which gives the freedom of programming p-type or n-type functionality for the same device at runtime. This enables the circuit designers to pack more functionality per computational unit. This saves processing costs as only one device type is required, and no doping and associated lithography steps are needed for this technology. In this paper, we present a complete design flow including both logic and physical synthesis for circuits based on SiNW RFETs. We propose layouts of logic gates, Liberty and LEF (Library Exchange Format) files to enable further research in the domain of these novel, functionally enhanced transistors. We show that in the first of its kind comparison, for these fully symmetrical reconfigurable transistors, the area after placement and routing for SiNW based circuits is 17% more than that of CMOS for MCNC benchmarks. Further, we discuss areas of improvement for obtaining better area results from the SiNW based RFETs from a fabrication and technology point of view. The future use of self-aligned techniques to structure two independent gates within a smaller pitch holds the promise of substantial area reduction.

The use of ferroelectric negative capacitance (NC) has been proposed as a promising way to reduce the power dissipation in nanoscale devices [1]. According to single-domain (SD) Landau theory, a hysteresis-free NC state in a ferroelectric might be stabilized in the presence of depolarization fields below a certain critical film thickness tF, SD. However, it is well-known that depolarization fields will cause the formation of domains in ferroelectrics to reduce the depolarization energy [2], which is rarely considered in the literature on NC [3]. The improvident use of SD Landau theory to model NC devices seems to be the main reason for the large discrepancy between experimental data and the current theory [4]. Here, we will show by simulation how anti-parallel domain formation can strongly limit the stability of the NC state in a metal-ferroelectric-insulator-metal (MFIM) structure, which is schematically shown in Fig. 1.

<p>Electrospinning has gained immense interests in recent years due to its potential application in various fields, including energy storage application. The V₂O₅/GO as a layered crystal structure has been demonstrated to fabricate nanofibers with diameters within a range of ~300nm through electrospinning technique. The porous, hollow, and interconnected nanostructures were produced by electrospinning formed by polymers such as Polyvinylpyrrolidone (PVP) and Polyvinyl alcohol (PVA), separately, as solvent polymers with electrospinning technique. </p> <p> </p> <p>In this study, we investigated the synthesis of a graphene-modified nanostructured V₂O₅ through modified sol-gel method and electrospinning of V₂O₅/GO hybrid. Electrochemical characterization was performed by utilizing Arbin Battery cycler, Field Emission Scanning Electron Microscopy (FESEM), X-ray powder diffraction (XRD), Thermogravimetric analysis (TGA), Mercury Porosimetery, and BET surface area measurement. </p> <p> </p> <p>As compared to the other conventional fabrication methods, our optimized sol-gel method, followed by the electrospinning of the cathode material achieved a high initial capacity of <b>342 mAh/g</b> at a high current density of 0.5C (171 mA/g) and the capacity retention of ~80% after 20 cycles. Also, the prepared sol-gel method outperforms the pure V₂O₅cathode material, by obtaining the capacity almost two times higher.</p> <p>The results of this study showed that post-synthesis treatment of cathode material plays a prominent role in electrochemical performance of the nanostructured vanadium oxides. By controlling the annealing and drying steps, and time, a small amount of pyrolysis carbon can be retained, which improves the conductivity of the V₂O₅ nanorods. Also, controlled post-synthesis helped us to prevent aggregation of electro-spun twisted nanostructured fibers which deteriorates the lithium diffusion process during charge/discharge of batteries.</p>

<p>  </p> <p>The development of the semiconductor industry is encountering a giant leap recently as Moorse’s is extended to the next levels. Advanced nanomanufacturing technology is the major challenge in the way. Higher resolution down to a few nanometers as well as higher throughput is always the key. As the optical lithography determines the feature size, the photomask is still in need of a low-cost and high resolution maskless patterning tool. In another aspect, the growing information allows the generation and storage of data at ever faster rates, which has led to the era of big data reaching a heroic amount of 7 zettabytes of total data in 2020. Future growth requires the total shipment of data storage capacity to double roughly every two years or less. For the future generation of magnetic data storage, the bit patterned medium (BPM) in combination with the current heat assisted magnetic recording (HAMR) is expected to increase the areal storage capacity by another order of magnitude by physically isolating magnetic bits at the nanoscale. Electron beam lithography (EBL) as a universal maskless lithography technique shows great resolution but has a high tool cost and low process throughput. Scanning probe lithography (SPL) is another family of nanoscale patterning techniques with low tool cost but the practical throughput is still limited. For example, dip pen nanolithography utilizes an AFM probe as a writing pen in direct patterning, but the ink delivery is limited by the rate of ink’s capillary transport. Other SPLs such as thermal probes with capabilities of 3D fabrication and surface oxidation via chemical reactions are all facing similar limitations in throughput. One way of breaking this limitation is to use parallel writing with millions of probes which also faces uniformity problems. </p> <p>In this Ph.D. dissertation, we report our Surfing Scanning Probe lithography (SSPL) method which can boost the scanning speed of SPL by several orders of magnitudes at a low cost by using a hydro-aero-dynamic scanning scheme. We use a homemade patterning head to continuously scan over a partially-wet spinning substrate at a linear speed of meters per second. The head carries several metallic tips which emit electrons and induce electrochemical reactions inside a gap of 10 nm scale. We use a liquid phase precursor and deliver it using the near-field electrospinning method and microfluid structures during the fast patterning. The best linewidth demonstrated is about 15 nm in full-width half maximum (FWHM) which can be further improved using smaller scanning gaps and sharp probe tips. Besides direct writing with a liquid precursor, SSPL can work with gas precursors as well enabled by nano plasma. The rate of material deposition is much high than conventional SPL. The SSPL system is a low-cost nanopatterning technology to produce patterns at high throughput and high resolution.</p>

The interferometric cantilever displacement detection in non-contact atomic force microscopy (NC-AFM) is in fundamental aspects explored and optimized. Furthermore, the opto-mechanical interaction of the light field with the cantilever is investigated in detail. Cantilevers are harmonic oscillators that are designed to have a high sensitivity for the detection of minute external forces typically originating from tip-sample interaction. In this work, however, the high sensitivity is used for detailed studies of opto-mechanical forces due to the radiation pressure of the light interacting with the cantilever. The interferometer in the NC-AFM setup consists of an optical cavity working similar to a Fabry-Pérot interferometer in combination with a reference interference arm working similar to a Michelson interferometer combining multi-beam interference with a reference beam resulting in a complex superposition of beams forming the interferometric intensity modulation signal. The character of the interferometer can be adjusted from predominant Michelson to predominant Fabry-Pérot characteristics by the optical loss inside the cavity. A systematic approach for accurate alignment, by using 3D intensity maps and intensity-over-distance curves, as well as the implications of deficient fiber-cantilever configurations are explored and the impact of the interferometer configuration on the detection system noise floor is investigated. A new physical property, namely, the Fabry-Perot enhancement factor is introduced that is a direct measure for the light intensity interacting with the cantilever compared to the reference beam intensity reflected back inside the fiber. The quantification of the optical loss yields an exact knowledge of the amount of light interacting with the cantilever that is crucial to understand opto-mechanical effects. The resulting opto-mechanical force varies sinusoidally during the course of one oscillation cycle. It is a key result of this work that the sinusoidal modification of the cantilever restoring force can be described analogue to the restoring force of a pendulum. This results in an observable amplitude dependent frequency shift of the cantilever oscillation, allowing a calculation of the ratio of the opto-mechanical force relative to the cantilever restoring force and thus allows an in-situ measurement of the cantilever stiffness with remarkable precision. Further investigation of the cantilever oscillation yields that other characteristic properties of the oscillation are significantly modified by the opto-mechanical interaction. The observed effective fundamental mode Q-factor drops significantly while the cantilever amplitude response to a certain excitation voltage increases. A discrete numerical model describing the cantilever as a 1D linear chain of mass points is implemented, yielding that the additional opto-mechanical force results in a partial pinning of the cantilever at the edges of the interferometric fringes. Pinning efficiently shifts energy from the fundamental mode to higher modes and modes of a pinned cantilever, resulting in a complex modal structure.

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Orientador: Jonas Contiero / Resumo: A contaminação ambiental causada por compostos orgânicos é um importante problema que afeta solos e água superficiais. Para reduzir ou remover esses poluentes, os locais contaminados são geralmente tratados com métodos físicos e químicos. No entanto, a maioria dessas técnicas de remediação é custosa e geralmente leva à remoção incompleta e à produção de resíduos secundários. A nanotecnologia consiste na produção e aplicação de estruturas extremamente pequenas, cujas dimensões estão na faixa de 1 a 100 nm, neste cenário a nanopartícula de ferro zero valente representa uma nova geração de tecnologias de remediação ambiental. É não tóxica, abundante, barata, fácil de produzir, e seu processo de produção é simples. No entanto, a fim de diminuir a tendência de agregação, a nanopartícula de ferro zero é frequentemente revestida com surfactantes. A maioria dos surfactantes é quimicamente sintetizado a partir de fontes petroquímicas, eles são persistentes ou parcialmente biodegradáveis, enquanto oferecem baixos riscos à saúde humana, esses compostos podem prejudicar plantas e animais. Para diminuir o uso de métodos químicos, a síntese e estabilização verde de nanomateriais metálicos apresentam-se como uma opção menos perigosa ao meio ambiente. Os biossurfactantes podem potencialmente substituir qualquer surfactante sintético, eles são compostos extracelulares produzidos por microrganismos, como bactérias, e cultivados em diferentes fontes de carbono, podendo ser substratoshidrofílico... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Environmental contamination caused by organic compounds is the most important challenge that affects a huge number of soils and water surfaces. To reduce or remove these pollutants, contaminated sites are usually treated using physical and chemical methods. However, most of these remediation techniques are expensive and commonly lead to incomplete removal and to the production of secondary wastes. Nanotechnology is the production and application of extremely small structures, whose dimensions are in the range of 1 to 100 nm and Nanoscale zero-valent iron represents a new generation of environmental remediation technologies, is non-toxic, abundant, cheap, easy to produce, and its reduction process requires little maintenance. Nonetheless, in order to diminish the tendency of aggregation, nanoscale zero-valent iron is often coated with surfactants. Most surfactants are chemically synthesized from petrochemical sources, they are slowly or partially biodegradable, while offer low harm to humans, such compounds can influence plants and animals. To decrease the use of chemical methods green synthesis and stabilization of metallic nanomaterials viable option. Biosurfactants can potentially replace virtually any synthetic they are extracellular compounds produced by microbes such as by bacteria and grown on different carbon sources containing hydrophobic/hydrophilic substrates. The biosurfactants have a wide variety of chemical structures and surface properties and among them is the ... (Complete abstract click electronic access below) / Doutor

Considerable jump and slip phenomena are observed at the non-equilibrium phase interface in microflows. Hence, accurate modelling of the liquid-vapour interface transport mechanisms that matches the observations is required, e.g. in applications such as micro/nanotechnology and micro fuel cells. In the sharp interface model, the classical Navier-Stokes-Fourier (NSF) equations can be used in the liquid and vapour phases, while the interface resistivities describe the jump and slip phenomena at the interface. However, resistivities are challenging to find from the measurements, and most of the classical kinetic theories consider them as constants. One possible approach is to determine them from a model that resolves the phase interface. In order to resolve the interface and the transport processes at and in front of the interface in high resolutions, there are two ways in general, microscopic or macroscopic. The microscopic studies are based either on molecular dynamics (MD) or kinetic models, such as the Enskog-Vlasov (EV) equation. The EV equation modifies the Boltzmann equation by considering dense gas effects, such as the interaction forces between the particles and their finite size. It can be solved by the Direct Simulation Monte Carlo (DSMC) method, which considers sample particles that stand in for thousands to hundred thousands of particles and determine most likely collisions based on interaction probabilities, but it is time-consuming and costly. Here, a closed set of 26-moment equations is numerically solved to resolve the liquid-vapour interface macroscopically while considering the dense gas and phase change effects. The 26-moment set of equations is derived by Struchtrup & Frezzotti as an approximation of the EV equation using Grad's moment method. The macroscopic moment equations resolve the phase interface in a high resolution competitive to the microscopic studies. The resolved interface visualizes the interface structure and the changes of the system variables between the two phases at the interface. The 26-moment equations are solved for a one-dimensional steady-state system for non-equilibrium evaporation/condensation process. Then, solutions are used to find the jump and slip conditions at the interface, which leads to determining the interface resistivities at different interface temperatures and non-equilibrium strengths from the Linear Irreversible Thermodynamics (LIT). The interface resistivities show their dependence on the temperature of the liquid at the interface as well as the strength of the non-equilibrium process. As a result, in further studies, similar systems can be modelled using the sharp interface method with the appropriate jump conditions at the phase interface that can be found from the determined EV interface resistivities. / Graduate

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