New fabrication techniques for PASS

The Planar Array of Superheated Superconductors was introduced by the UBC group in 1990. It is a regular array of micron-sized spheres of indium or tin that acts as a detector of radiation or particles in a similar fashion to the Superheated Superconducting Granule Detector. Over the years, it was demonstrated that this device exhibited good energy sensitivity, a narrow spread of individual transition temperatures, position sensitivity, and, using line geometry, partial avalanche effects. The great difficulty, however, was to produce a detector of sufficient size. We discuss three possible approaches to this problem. The first method is to fabricate the array photolithographically in much the same way as before, but on a much larger scale. The second way is to emboss squares in a metal film with an ultrafine cutting tool before melting. The third technique involves depositing the metal on to a structured surface then melting. Some experimental tests are described.     

Automated nanomanipulation for nanodevice construction

Nanowire field-effect transistors (nano-FETs) are nanodevices capable of highly sensitive, label-free sensing of molecules. However, significant variations in sensitivity across devices can result from poor control over device parameters, such as nanowire diameter and the number of electrode-bridging nanowires. This paper presents a fabrication approach that uses wafer-scale nanowire contact printing for throughput and uses automated nanomanipulation for precision control of nanowire number and diameter. The process requires only one photolithography mask. Using nanowire contact printing and post-processing (i.e. nanomanipulation inside a scanning electron microscope), we are able to produce devices all with a single-nanowire and similar diameters at a speed of ~1 min/device with a success rate of 95% (n = 500). This technology represents a seamless integration of wafer-scale microfabrication and automated nanorobotic manipulation for producing nano-FET sensors with consistent response across devices.     

Advanced modeling techniques for micromagnetic systems

We present a review of micromagnetic and magnetotransport modeling methods which go beyond the standard model. We first give a brief overview of the standard micromagnetic model, which for (i) the steady-state (equilibrium) solution is based on the minimization of the free energy functional, and for (ii) the dynamical solution, relies on the numerical solution of the Landau-Lifshitz-Gilbert (LLG) equation. We present three complements to the standard model, i.e., (i) magnetotransport calculations based on ohmic conduction in the presence of the anisotropic magnetoresistance (AMR) effect, (ii) magnetotransport calculations based on spin-dependent tunneling in the presence of single charge tunneling (Coulomb blockade) effect, and (iii) stochastic micromagnetics, which incorporates the effects of thermal fluctuations via a white-noise thermal field in the LLG equation. All three complements are of practical importance: (i) magnetotransport model either in the ohmic or tunneling transport regimes, enables the conversion of the micromagnetic results to the measurable quantity of magnetoresistance ratio, while (ii) stochastic modeling is essential as the dimensions of the micromagnetic system reduces to the deep submicron regime and approaches the superparamagnetic limit.     

Sub-30 nm gate template fabrication for nanoimprint lithography using spacer patterning technology

In this study, we present a spacer patterning technology for sub-30 nm gate template which is used for nano-scale MOSFETs fabrication. A spacer patterning technology using a poly-silicon micro-feature and a chemical vapor deposition (CVD) SiO2 spacer has been developed, and the sub-30 nm structures by conventional dry etching and chemical mechanical polishing are demonstrated. The minimum-sized features are defined not by the photolithography but by the CVD film thickness. Therefore, this technology yields a large-area template with critical dimension of minimum-sized features much smaller than that achieved by optical lithography.     

Design and fabrication of a photosensing nanodevice structure with CdSe and Au nanoparticles on a silicon chip

A newly developed four-layered photosensing nanodevice was fabricated by integrating nanoparticles (NPs) on a silicon substrate. Through ionic interaction, negatively charged Au NPs (/spl sim/15 nm) were assembled in alternate layers with positively charged CdSe NPs (/spl sim/5 nm) on the silicon oxide surface between the two Al electrodes. The silicon oxide surface after each step of the fabrication process was observed and evaluated by images obtained from the scanning electron microscope. By applying voltage biases across the electrodes, the currents were measured in the dark and under illumination using a 375-nm laser. It was found that a constant photocurrent increment can be obtained for different voltage biases, and the nanodevice structure with a longer length had less conductivity but a larger increment of photocurrent after illumination. In addition, the efficiency rate of photocurrent generation is much higher in comparison to that obtained from CdSe thin film. The fabrication process integrated a newly developed model of a diode-resistor array of semiconductor-metal junctions between CdSe and Au NPs (nano-Schottky-diode structures), which can successfully explain the measured results. While nanotechnology has unprecedented advantages over the traditional silicon electronics, its technology presents physical challenges. However, the success of the fabrication of the multilayered photosensing nanodevice directly on the silicon chip paves the way for further applications and research.     

System and fabrication techniques for a solid-state random-access mass memory

This paper describes a development program aimed at improving processing speeds by providing data processing systems with random-access memories approaching the speed of ferrite-core matrix memories, but at a cost that economically permits of mass-memory capacities. Compatible system and fabrication techniques were devised to reach the low cost objective. The paper details the system and fabrication techniques, and in addition to demonstrating low memory cost, describes small power, weight, and size characteristics that might be important in special applications.     

Advanced preprocessing techniques for linear and quadratic programming

The paper presents an overview on the preprocessing techniques of linear programming. A new reduction technique is also introduced and the presolve is extended to mixed integer and quadratic programming problems. Numerical results are presented to demonstrate the impact of presolving in interior point and simplex implementations. The demonstrative results are given on large-scale linear, mixed integer and quadratic programming test problems.Cs. Mészáros: Supported in part by Alexander von Humboldt Foundation Correspondence to: U.H. Suhl     

EBL- and AFM-based techniques for nanowires fabrication on Si/SiGe

Two approaches for sub-100 nm patterning are applied to Si/SiGe samples.The first one combines electron beam lithography (EBL) and anisotropic wet etching to fabricate wires with triangular section whose top width is narrower than the beam size. Widths as small as 20 nm on silicon and 60 nm on Si/SiGe heterostructures are obtained.The second lithographic approach is based on the local anodization of an aluminum film induced by an atomic force scanning probe. Using atomic force microscopy (AFM) anodization and selective wet etching, aluminum and aluminum oxide nanostructures are obtained and used as masks for reactive ion etching (RIE). Sub-100 nm wide wires are fabricated on Si/SiGe substrates.     

Ionized-cluster beam deposition and epitaxy as fabrication techniques for electron devices

It is shown that the ionized-cluster beam deposition and epitaxy techniques are useful for semiconductor device fabrication. The deposited film shows good adhesion, good conduction even in a very thin film and a good crystalline state. These techniques have been applied to interconnections and semiconductor material preparation for devices and integrated circuits. Solar and electroluminescent cell have been fabricated.     

Advanced techniques for characterization of ion beam modified materials

Understanding the mechanisms of damage formation in materials irradiated with energetic ions is essential for the field of ion-beam materials modification and engineering. Utilizing incident ions, electrons, photons, and positrons, various analysis techniques, including Rutherford backscattering spectrometry (RBS), electron RBS, Raman spectroscopy, high-resolution X-ray diffraction, small-angle X-ray scattering, and positron annihilation spectroscopy, are routinely used or gaining increasing attention in characterizing ion beam modified materials. The distinctive information, recent developments, and some perspectives in these techniques are reviewed. Applications of these techniques are discussed to demonstrate their unique ability for studying ion-solid interactions and the corresponding radiation effects in modified depths ranging from a few nm to a few tens of μm, and to provide information on electronic and atomic structure of the materials, defect configuration and concentration, as well as phase stability, amorphization and recrystallization processes. Such knowledge contributes to our fundamental understanding over a wide range of extreme conditions essential for enhancing material performance and also for design and synthesis of new materials to address a broad variety of future energy applications.     

Advanced characterization techniques for solid state lithium battery research

Solid state batteries have attracted significant attention within the battery community over the last decade, due to the feasibility of developing a new generation of rechargeable Li batteries offering safer and long-term performance. However, many scientific and technical challenges and difficulties still need to be overcome before this new technology can be used commercially. Advanced characterization techniques provide powerful tools for studying these complex and elusive chemical/physical processes in solid-state batteries. Over the last decade, researchers have explored many sophisticated ex-situ and in-situ techniques, such as synchrotron X-ray techniques, solid-state NMR techniques, neutron scattering techniques, etc., to probe the undisclosed underlying mechanisms of solid-state batteries. In this review, we present a comprehensive overview of recent advances in these three characterization techniques in solid state battery research. Some perspectives of the future evolution of the techniques are also presented.     

Colloidal lithography and current fabrication techniques producing in-plane nanotopography for biological applications

Substrate topography plays a vital role in cell and tissue structure and function in situ, where nanometric features, for example, the detail on single collagen fibrils, influence cell behaviour and resultant tissue formation. In vitro investigations demonstrate that nanotopography can be used to control cell reactions to a material surface, indicating its potential application in tissue engineering and implant fabrication. Developments in the catalyst, optical, medical and electronics industries have resulted in the production of nanopatterned surfaces using a variety of methods. The general protocols for nanomanufacturing require high resolution and low cost for fabricating devices. With respect to biological investigations, nanotopographies should occur across a large surface area (ensuring repeatability of experiments and patterning of implant surfaces), be reproducible (allowing for consistency in experiments), and preferably, accessible (limiting the requirement for specialist equipment). Colloidal lithography techniques fit these criteria, where nanoparticles can be utilized in combination with a functionalized substrate to produce in-plane nanotopographies. Subsequent lithographic processing of colloidal substrates utilizing, for example, reactive ion etching allows the production of modified colloidal-derived nanotopographies. In addition to two-dimensional in-plane nanofabrication, functionalized structures can be dip coated in colloidal sols, imparting nanotopographical cues to cells within a three-dimensional environment.     

聚光器薄膜附着力机理与制备工艺的探讨

研究太阳能聚光器薄膜在制备过程中附着力存在的有关问题。阐述薄膜在生长过程中影响薄膜附着力的各种因素，针对其相关因素作了具体的理论分析，并在真空镀膜实验的基础上，探讨了提高蒸发镀膜附着力的具体方法。     

Nano patterning of cone dots and nano constrictions of negative e-beam resist for single electron transistor fabrication

We present an optimization of nano dot of negative tone e-beam resist which is a very important step in single electron transistor fabrication process. The optimum design of dot and nano constriction plays a significant role in determining optimum etching resolution and single electron transistor performance. In this research, we have optimized nano dot and nano constriction dimensions of resist by controlling some parameters, such as e-beam dose, spin speed, pre-bake time and image development time. However, a nano constriction design variety of 120–200 nm in width was carried out to reach the optimum design. In this paper, the fabrication process of cone nano dots using e-beam lithography with considering proximity effect is reported. As nano constriction design decreased, cone nano dot changed to pyramid nano dot and the compression effect on the dot also significantly increased as well.     

A hybrid plasmonic-photonic nanodevice for label-free detection of a few molecules

Noble metal nanowaveguides supporting plasmon polariton modes are able to localize the optical fields at nanometer level for high sensitivity biochemical sensing devices. Here we report on the design and fabrication of a novel photonic-plasmonic device which demonstrates label-free detection capabilities on single inorganic nanoparticles and on monolayers of organic compounds. In any case, we determine the Raman scattering signal enhancement and the device detection limits that reach a number of molecules between 10 and 250. The device can be straightforwardly integrated in a scanning probe apparatus with the possibility to match topographic and label-free spectroscopic information in a wide range of geometries.     

Review on the fabrication techniques of A-15 superconductors

This Paper reviews the present state-of-the-art of preparing multifilamentary A-15 superconductors. The most common types, Nb₃Sn and V₃Ga, are presently produced by the so-called bronze process. The highest J_c (overall) = 3.5 × 10⁴ cm⁻² (at 15 T and 4.2 K), obtained for bronze processed Nb₃Sn composites through Ti addition, has pushed the useful limit of this material from 12 to 16 T. Similarly a J_c of 1 × 10⁵ A cm⁻² (at 20 T and 4.2 K) for the A-15 V₃Ga has been attained through elemental additions to the core and the bronze matrix. To circumvent the problem of work-hardening of the bronze, several variations of the bronze process such as the internal tin method, the Nb tube method, the ECN method and jelly roll method have also been upgraded to commercial scale. Composites of Nb₃Sn and V₃Ga have been recently produced successfully on a laboratory scale following the so called in situ technique. These composites not only have a superior J_c value but display improved strain tolerance due to the ultrafine nature of the filaments formed in situ. In situ filamentary A-15 composites with high J_c values have also been produced by following the powder metallurgy technique. The infiltration technique has been found useful for producing high field Nb₃(Al, Ge), Nb₃(Al, Si) and Nb₃Sn composite conductors with high ε_irr. Superior materials such as Nb₃Al, Nb₃Ga and Nb₃(Al,Ge) with high J_c performance have been synthesized using the laser beam technique. Nb₃Ge tapes with T_c = 21 K and J_c = 10⁵ A cm⁻² (at 18 T and 4.2 K) have been successfully produced on a laboratory scale by following the CVD technique. Thus, there are several available options from which to choose a technique for fabricating filamentary composites of ubiquitous Nb₃Sn and V₃Ga. New techniques for fabricating superior materials like Nb₃Al, Nb₃Ga, Nb₃Ge and Nb₃(Al, Ge) also seem to be at an advanced stage of development.     

Application of ultrasonic testing techniques on austenitic welds for fabrication and in-service inspection

This paper describes some practical considerations relating to the ultrasonic testing of weld joints in austenitic components, based on the author's experience with components manufactured for, and in service in, nuclear power stations. Problems caused by the effect of grain structure, spurious indications and attenuation of the ultrasound are discussed. The importance of acquiring adequate data from reference blocks is emphasized, and the uses and limitations of various types of angle probe are illustrated.