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Showing papers in "MRS Proceedings in 2003"


Journal ArticleDOI
TL;DR: In this paper, the authors report methods of surface modification and device construction which consistently result in lab-scale pentacene-based TFTs with mobilities at or above 5 cm2/Vs.
Abstract: We report here methods of surface modification and device construction which consistently result in lab-scale pentacene-based TFTs with mobilities at or above 5 cm2/Vs. Surface modifications include polymeric ultrathin films presenting a passivated interface on which the semiconductor can grow. High performance TFTs have been fabricated on a variety of dielectric materials, both organic and inorganic, and are currently being implemented in manufacturable constructions. Our surface modifications have also proven useful for substituted pentacene materials and for a variety of other organic semiconductors. In addition, we report an all organic active layer, rf-powered integrated circuit. Further experiments and statistical analyses are underway to explain the elevated mobility in our samples, and efforts have been made to confirm these results through collaboration.

259 citations


Journal ArticleDOI
TL;DR: In this article, self-assembled monolayers (SAMs) are used to passivate unpassivated Al nanoparticles using a perfluoroalkyl carboxylic acid.
Abstract: Surface passivation of unpassivated Al nanoparticles has been realized using self-assembled monolayers (SAMs). Nanoscale Al particles were prepared in solution by catalytic decomposition of H3Al·NMe3 or H3Al·N(Me)Pyr by Ti(OiPr)4 and coated in situ using a perfluoroalkyl carboxylic acid SAM. Because the Al particles are prepared using wet chemistry techniques and coated in solution, they are free of oxygen passivation. This SAM coating passivates the aluminum and appears to prevent the oxidation of the particles in air and renders the composite material, to some extent, soluble in polar organic solvents such as diethyl ether. Characterization data including scanning electron microscopy , transmission electron microscopy, thermogravimetric analysis, and attenuated total reflectance-Fourier transform infrared spectroscopy of prepared materials are presented.

218 citations


Journal ArticleDOI
TL;DR: In this article, the authors developed a technique for synthesizing nano-particles of different sizes and shapes to reduce any possible hazards associated with the handling of nano-sized particles as well as unwanted particle oxidation, various passivation procedures have been developed.
Abstract: Nano-sized energetic metals and boron particles (with dimensions less than 100 nanometers) possess desirable combustion characteristics such as high heats of combustion and fast energy release rates. Because of their capability to enhance performance, various metals have been introduced in solid propellant formulations, gel propellants, and solid fuels. There are many advantages of incorporating nano-sized materials into fuels and propellants, such as: 1) shortened ignition delay; 2) shortened burn times, resulting in more complete combustion in volume-limited propulsion systems; 3) enhanced heat-transfer rates from higher specific surface area; 4) greater flexibility in designing new energetic fuel/propellants with desirable physical properties; 5) nano-particles can act as a gelling agent to replace inert or low-energy gellants; 6) nano-sized particles can also be dispersed into high-temperature zone for direct oxidation reaction and rapid energy release, and 7) enhanced propulsive performance with increased density impulse. In view of these advantages, numerous techniques have been developed for synthesizing nano-particles of different sizes and shapes. To reduce any possible hazards associated with the handling of nano-sized particles as well as unwanted particle oxidation, various passivation procedures have been developed. Some of these coating materials could enhance the ignition and combustion behavior, others could increase the compatibility of the particles with the surrounding material. Many researchers have been actively engaged in the characterization of the ignition and combustion behavior of nano-sized particles as well as the assessment of performance enhancement of propellants and fuels containing energetic nano-particles. For example, solid fuels could contain a significant percentage of nano-sized particles to increase the mass-burning rate in hybrid rocket motors, the regression rate of solid propellants can be increased by several times when nano-sized particles are incorporated into the formulation. Specifically, hybrid motor data showed that the addition of 13% energetic aluminum powders can increase the linear regression rate of solid HTPB-based fuel by 123% in comparison to the non-aluminized HTPB fuel at a moderate gaseous oxidizer mass flow rate. Strand burner studies of two identical solid propellant formulations (one with 18% regular aluminum powder and the other with 9% aluminum replaced by Alex® powder) showed that nano-sized particles can increase the linear burning rate of solid propellants by 100%. In addition to solid fuels and propellants, spray combustion of bipropellants has been conducted using gel propellants impregnated with nano-sized boron particles as the fuel in a rocket engine. High combustion efficiencies were obtained from burning nano-sized boron particles contained in a non-toxic liquid-fuel spray. Materials characterization such as chemical analyses to determine the active aluminum content, density measurements, and imaging using an electron microscope have been performed on both neat nano-sized particles and mixtures containing the energetic materials. In general, using energetic nano-sized particles as a new design parameter, propulsion performance of future propellants and fuels can be greatly enhanced.

122 citations


Journal ArticleDOI
TL;DR: In this article, the authors demonstrate a bridging technology based on an inkjetted polyimide interlevel dielectric and demonstrate multilevel interconnect and passive component structures including conductor patterns, crossover bridges, and tapped planar spiral inductors.
Abstract: In recent years, there has been tremendous interest in all-printed electronics as a means of achieving ultra-low-cost electronic circuits with uses in displays and disposable electronics applications such as RFID tags. While there have been a few demonstrations of printed organic transistors to date, there has been little work on the associated passive component and interconnection technologies required to enable the development of all-printed RFID circuits. In particular, low-resistance conductors are crucial to achieve the high-Q inductors necessary for RFID. Here, we demonstrate inkjetted nanoparticle-Au conductors on plastic with sheet resistances as low as 0.03 ohms/square. We describe the optimization of the jetting parameters, and their impact on final film morphology and electrical properties. We also demonstrate a bridging technology based on an inkjetted polyimide interlevel dielectric. Using this process, we demonstrate multilevel interconnect and passive component structures including conductor patterns, crossover bridges, and tapped planar spiral inductors. Together, these represent an important step towards the realization of all-printed RFID.

100 citations


Journal ArticleDOI
TL;DR: In this article, a synthetic methodology has been developed to get a well-dispersed and homogeneous aqueous suspension of Fe3O4 nanoparticles in the size range of 8-10 nm.
Abstract: Magnetic nanoparticles have found application in medical diagnostics such as magnetic resonance imaging and therapies such as cancer treatment. In these applications, it is imperative to have a biocompatible solvent such as water at optimum pH for possible bio-ingestion. In the present work, a synthetic methodology has been developed to get a well-dispersed and homogeneous aqueous suspension of Fe3O4 nanoparticles in the size range of 8–10 nm. The surface functionalization of the particles is provided by citric acid. The particles have been characterized using transmission electron microscopy, magnetization measurements with a superconducting quantum interference device, FTIR spectroscopy (for surfactant binding sites), thermogravimetric studies (for strength of surfactant binding), and x-ray photoelectron spectroscopy and x-ray diffraction (for composition and phase information). The carboxylate functionality on the surface provides an avenue for further surface modification with fluorescent dyes, hormone linkers etc for possible cell-binding, bioimaging, tracking, and targeting.

66 citations


Journal ArticleDOI
TL;DR: In this paper, the formation of silver nanoparticles in the presence of silver-binding peptides was demonstrated by transmission electron microscopy, which revealed a variety of crystal morphologies such as hexagons, triangles and spheres.
Abstract: The use of biomolecules in the creation of inorganic materials offers an alternative to conventional synthetic methods. Biomolecules are currently used to control nucleation and growth of inorganic nanoparticles. Here we demonstrate the formation of silver nanoparticles in the presence of silver-binding peptides. Examination of the silver nanoparticles by transmission electron microscopy revealed a variety of crystal morphologies such as hexagons, triangles and spheres. The peptides serve to reduce the silver ions in the aqueous solution to metallic silver as well as control crystal growth. The nucleation property of peptides can be used as tool for bottom-up fabrication.

61 citations


Journal ArticleDOI
TL;DR: In this article, the area dependence of switching in both Cr/p + a-Si:H/Ag(Al) and Cr/ p + μc-Si/Ag (Al) filament switches is investigated.
Abstract: We report on the area dependence of switching in both Cr/ p + a-Si:H/Ag(Al) and Cr/ p + μc-Si/Ag(Al) filament switches. The doped amorphous (a-Si:H) or microcrystalline (μc-Si) thin Si layers are made by hot-wire chemical vapor deposition. The device active region area (A) is varied over 5 orders of magnitude, from 10 -7 to 10 -2 cm 2 , using photolithographically defined Ag and Al top contacts. Before switching, the resistance of 100-μm 2 devices is normally about 100 kΩ for μc-Si and 10 GΩ for a-Si:H. After switching with applied current ramps, the resistance decreases to a few hundred ohms in all a-Si devices and to a few thousands ohms in μc-Si devices. In both μc-Si and a-Si:H devices, the switching voltage (V sw ) decreases with increasing device area according to V sw ~ V 0 -αln(A/A 0 ) with α=0.3V for a-Si:H and α=0.04V for μc-Si. For both materials, the switching current roughly obeys the power law I sw ∞ A β with β~1. A statistical model is proposed to explain the area scaling of the switching voltage and relate the parameters to the material properties.

58 citations


Journal ArticleDOI
TL;DR: In this paper, the absorber is prepared by electrodeposition techniques, while molybdenum, copper or stainless steel (SS) are used as flexible substrates.
Abstract: The development of a low cost roll-to-roll production process for CIGS remains an attractive goal. In the present approach, the absorber is prepared by electrodeposition techniques, while molybdenum, copper or stainless steel (SS) are used as flexible substrates. Two electrodeposition routes are evaluated: sequential plating of Cu, In and Ga followed by Se evaporation is compared to simultaneous (= ternary) electrodeposition of Cu, In and Se. Ternary electrodeposition yields 7.5 % efficiency on stainless steel. The sequential process leads to 9.0 % cell efficiency on copper and on stainless steel substrates.

52 citations


Journal ArticleDOI
TL;DR: In this paper, a flexible glass substrate down to a thickness of 50μm has been developed, which can be used in conventional display manufacturing processes which include several thin film process steps.
Abstract: New applications in the electronics market ranging from foldable displays in mobile phones to wearable displays in clothes generate a high demand for flexible materials especially for substrates. The upcoming OLED technology shows some advantages in comparison with conventional LCDs and enables real flexible or shaped displays. Moreover, the wearable displays have a barely need for flexible electronic circuits. At a first glance polymer foils are the materials of choice for flexible substrates and for electronic circuits but in general they suffer from thermal instability as well as from high permeation rates for gases and water and hence chemical stability of critical materials such as LC’s or low work function materials. In contrast, even ultra thin glass sheets have excellent barrier properties and show sufficient bending properties if they are thinner than 100μm. Flexible glass substrates down to a thickness of 50μm have been developed. The deposition of an organic coating helps to overcome significantly the lack of mechanical stability. Therefore, our flexible glass substrates can be used in conventional display manufacturing processes which include several thin film process steps. Moreover, they are suited for production of flexible PCB’s.

51 citations


Journal ArticleDOI
TL;DR: In this paper, a low-cost fabrication approach for vertical system integration is introduced, which takes advantage of wafer level processing to avoid increasing package sizes and expensive single component assembling processes.
Abstract: In the last years strong efforts were made to miniaturize microelectronic systems. Chip scale packages, flip chips and multichip modules are now commonly used in a great variety of products (e. g. mobile phones, hand-held computers and chip cards). Future microelectronic applications require significantly more complex devices with increased functionality and performance. Due to added device content, chip area will also increase. Performance, multi-functionality and reliability of microelectronic systems will be limited mainly by the wiring between the subsystems (so called “wiring crisis”), causing a critical performance bottleneck for future IC generations. 3D System Integration provides a base to overcome these drawbacks. Furthermore, systems with minimum volume and weight as well as reduced power consumption can be realized for portable applications. 3D integrated systems show reduced chip areas and enable optimized partitioning, both which decrease the fabrication cost of the system. An additional benefit is the enabling of minimal interconnection lengths and the elimination of speed-limiting inter-chip interconnects. 3D concepts which take advantage of wafer level processing to avoid increasing package sizes and expensive single component assembling processes have the potential to integrate passive devices resistors, inductors and capacitors into the manufacturing system and provide full advantage for system performance. The ITRS roadmap predicts an increasing demand for systems-on-a-chip (SoC) [1]. Conventional fabrication is based on embedded technologies which are cost intensive. A new low cost fabrication approach for vertical system integration is introduced. The wafer-level 3D SoC technology, optimized to the capability for chip-to-wafer stacking has the potential to replace embedded technologies based on monolithic integration.

50 citations


Journal ArticleDOI
TL;DR: In this article, the first inkjet-printed pentacene transistor was fabricated using a substrate-gated transistor structure in conjunction with an inkjet printed Pentacene precursor active layer.
Abstract: Pentacene is one of the most promising organic materials for organic transistor fabrication, since it offers higher mobility, better on-off ratio, improved environmental stability, and better reliability than most other organic semiconductors. However, its severe insolubility renders it useless for the solution-based fabrication of electronic devices. Solution-based processing is the key to enabling ultra-low-cost circuit fabrication, since it eliminates the need for lithography, subtractive processing, and vacuum-based film deposition. Using a recently developed soluble pentacene precursor, we demonstrate the first inkjet-printed pentacene transistor fabricated to date. This is achieved using a substrate-gated transistor structure in conjunction with an inkjetprinted pentacene precursor active layer. After deposition, the precursor is converted to pentacene via heating, through the decomposition of the Diels-Alder product. As the anneal temperature increases above 120°C, performance increases dramatically. The process is therefore compatible with numerous low-temperature plastics. As the anneal time is increased to several minutes, performance likewise increases through increased precursor decomposition. However, exposure to excess temperatures or times tends to degrade performance. This is caused by morphological and chemical changes in the pentacene film. Optimization of the anneal process alone has resulted in the demonstration of transistors with an on-off ratio of >10 5 and field-effect mobility of >0.01cm 2 /V-s, attesting to the great promise of this material.

Journal ArticleDOI
TL;DR: In this paper, high-energy density metastable nanocomposites with high energy density, were prepared by arresting the milling process prior to the spontaneous reaction, and the resulting powders were structurally characterized by electron microscopy and x-ray diffraction.
Abstract: Highly metastable, nano-scale energetic materials were prepared by Arrested Reactive Milling (ARM). When reactive milling is carried out with materials systems suitable for Self-Propagating High Temperature Synthesis (SHS), reaction between the components occurs spontaneously and violently after a certain period of milling. In this research, metastable nanocom-posites with high energy density, were prepared by arresting the milling process prior to the spontaneous reaction. Products thus obtained are powders with particle sizes in the 10–50 μm range. Individual particles are intimate mixtures of reactive components, comparable to Metast-able Intermolecular Composites (MIC), with near theoretical maximum density. The time of arrest determines the degree of grain refinement and therefore the sensitivity to mechanical, electrical, or thermal initiation. Particle sizes of the product powders can be adjusted by appropriate choice of milling parameters. This paper describes the application of ARM to the material systems Al-Fe2O3 and Al-MoO3. After empirical determination of optimum milling parameters, the reactive composites are structurally characterized by electron microscopy and x-ray diffraction. First results of combustion tests are presented.

Journal ArticleDOI
TL;DR: The first concept of a piezoelectric transformer (PT) was proposed by C.A. Rosen, K. Fish, and H.C. Rothenberg and was described in the U.S. Patent 2,830,274.
Abstract: The initial concept of a piezoelectric transformer (PT) was proposed by C.A. Rosen, K. Fish, and H.C. Rothenberg and is described in the U.S. Patent 2,830,274, applied for in 1954. Fifty years later, this technology has become one of the most promising alternatives for replacing the magnetic transformers in a wide range of applications. Piezoelectric transformers convert electrical energy into electrical energy by using acoustic energy. These devices are typically manufactured using piezoelectric ceramic materials that vibrate in resonance. With appropriate designs it is possible to step-up and step-down the voltage between the input and output of the piezoelectric transformer, without making use of wires or any magnetic materials. This technology did not reach commercial success until early the 90s. During this period, several companies, mainly in Japan, decided to introduce PTs for applications requiring small size, high step-up voltages, and low electromagnetic interference (EMI) signature. These PTs were developed based on optimizations of the initial Rosen concept, and thus typically referred to as “Rosen-type PTs”. Today’s, PTs are used for backlighting LCD displays in notebook computers, PDAs, and other handheld devices. The PT yearly sales estimate was about over 20 millions in 2000 and industry sources report that production of piezoelectric transformers in Japan is growing steadily at a rate of 10% annually. The reliability achieved in LCD applications and the advances in the related technologies (materials, driving circuitry, housing and manufacturing) have currently spurred enormous interest and confidence in expanding this technology to other fields of application. This, consequently, is expanding the business opportunities for PTs.

Journal ArticleDOI
TL;DR: In this article, the authors compare junction performance and integratablity of fast-ramp spike, flash, SPER and laser annealing down to 45nm CMOS, and show that SPER offers the best junction abruptness ( 4E20at/cm3) and less transistor modifications.
Abstract: Due to integration concerns, the use of meta-stable junction formation approaches like laser thermal annealing (LTA), solid phase epitaxial regrowth (SPER), and flash annealing has largely been avoided for the 90nm CMOS node. Instead fast-ramp spike annealing has been optimised along with co-implantation to satisfy the device requirements, often with the help from thin offset spacers. However for the 65nm and 45nm CMOS node it is widely accepted that this conventional approach will not provide the required pMOS junctions, even with changes in the transistor architecture. In this work, we will compare junction performance and integratablity of fast-ramp spike, flash, SPER and laser annealing down to 45nm CMOS. The junction depth, abruptness and resistance offered by each approach are balanced against device uniformity, deactivation and leakage. Results show that the main contenders for the 45nm CMOS are SPER and flash annealing – but both have to be rigorously optimised for regrowth rates, amorphous positioning and dopant and co-implant profiles. From the two, SPER offers the best junction abruptness ( 4E20at/cm3) and less transistor modifications. As expected, Ge and F co-implanted spike annealed junctions do not reach the 45nm node requirements. For full-melt LTA, poly deformation on isolation can be reduced but geometry effects result in unacceptable junction non-uniformity.

Journal ArticleDOI
TL;DR: In this article, a variety of standard particle characterization techniques were applied to the fifteen types of particles examined in this study and the results tabulated, and some of the parameters measured were average particle diameter, specific surface area, amount of active content, and oxide layer thickness.
Abstract: Energetic nano-sized particles have been shown to have a great potential for use in the aerospace propulsion applications. Some of the unique combustion properties of nano-particles such as very rapid ignition and short combustion times make them particularly valuable for propulsion systems; they can be included in solid fuels, solid propellants, or even as energetic gellant in liquid systems. However, due to the novelty of the application and rapid development of production techniques, there is no comprehensive understanding of what characteristics of a nano-sized particle are important in contributing to desirable performance and ease of processing into a final usable form. Previous studies have shown that HTPB-based solid fuels containing various types of nano-sized particles showed differing performance results when tested in the same hybrid rocket motor under identical conditions. Many of these particles have data available only on the basic composition (aluminum, boron, boron carbide, etc.), average diameter, and/or BET surface area. In order to better understand and correlate observed combustion behavior with intrinsic material properties, the particles of interest need to be better characterized. A variety of standard particle characterization techniques were applied to the fifteen types of particles examined in this study and the results tabulated. Some of the parameters measured were average particle diameter, specific surface area, amount of active content, and oxide layer thickness. Trends in propulsion performance measured using a parameter of great interest to the hybrid rocket community (fuel mass burning rate) in general matched trends in particle characteristics (i.e. active content, surface area), but there were some noticeable exceptions. This study indicates that there is still much more to learn about the correlation between physical and chemical properties and measured combustion performance. Other parameters that should be examined in the future include particle size distribution, degree of agglomeration, reactivity and thermal effects (oxidation rate, onset temperature for oxidation exotherm, heat release associated with any excess stored energy), etc.

Journal ArticleDOI
TL;DR: In this article, the optical properties of arrays of closely spaced metal nanoparticles were investigated in view of their potential to guide electromagnetic energy with a lateral mode confinement below the diffraction limit of light.
Abstract: We investigate the optical properties of arrays of closely spaced metal nanoparticles in view of their potential to guide electromagnetic energy with a lateral mode confinement below the diffraction limit of light. Finite-difference time-domain simulations of short arrays of noble metal nanospheres show that electromagnetic pulses at optical frequencies can propagate along the arrays due to near-field interactions between plasmon-polariton modes of adjacent nanoparticles. Near-field microscopy enables the study of energy transport in these plasmon waveguides and shows experimental evidence for energy propagation over a distance of 0.5 νm for plasmon waveguides consisting of spheroidal silver particles fabricated using electron beam lithography.

Journal ArticleDOI
TL;DR: In this paper, the efficiency of one-and two-electron oxidants in oxidative dissolution of UO2 has been investigated by measuring the U(VI)-concentration in solution after ex...
Abstract: In this work, the efficiency of one- and two-electron oxidants in oxidative dissolution Of UO2 has been investigated. This was accomplished by measuring the U(VI)-concentration in solution after ex ...

Journal ArticleDOI
TL;DR: In this article, the authors proposed a secondary barrier that results from the conduction band offset between CIGS and the commonly employed CdS window layer, which produces a second diode with the same polarity and in series with the primary photodiode.
Abstract: CIGS solar cells in many cases show a failure of light/dark superposition of their current-voltage (J-V) curves. Such failure generally becomes more pronounced at lower temperatures. J-V measurements under red light may also show an additional distortion, known historically as the “red kink”. The proposed explanation is that a secondary barrier results from the conduction band offset between CIGS and the commonly employed CdS window layer. This barrier produces a second diode with the same polarity and in series with the primary photodiode. The secondary-diode barrier height is modified by photoinduced changes of trap occupancy in the CdS layer, hence creating a voltage shift between dark and light conditions. Numerical modeling of the proposed explanation, including a band offset consistent with experimental and theoretical values, gives a very good fit to measured light and dark J-V curves over a wide temperature range. It also predicts the observed difference between illuminated J-V curves with photon energy above the CdS band gap, and those with sub-band-gap illumination.

Journal ArticleDOI
TL;DR: In this article, N-type multi-walled nanotubes were synthesized by nitrogen doping using pyridine and pryidine-melamine mixtures in chemical vapor deposition, and their donor states were verified by Scanning Tunneling Spectroscopy.
Abstract: N-type multi-walled nanotubes were synthesized by nitrogen doping using pyridine and pyridine-melamine mixtures in chemical vapor deposition, and their donor states were verified by Scanning Tunneling Spectroscopy. Tunneling Electron Microscopy reveals small amounts of residual catalyst and Scanning Electron Microscopy show well aligned mats of the Nitrogen doped nanotubes. Nitrogen is present in the lattice of these MWNTs as pyridine structures and CNx structures. Raman scattering measurements were performed as a function of increasing growth temperature and the results compared to previously studied boron doped multiwalled nanotubes.

Journal ArticleDOI
TL;DR: In this paper, the utilization of sol-gel chemical methodology to prepare nanostructured energetic materials as well as the concepts of nanoenergetics is described, and the preparation and characterization of two totally different compositions is detailed.
Abstract: The utilization of sol-gel chemical methodology to prepare nanostructured energetic materials as well as the concepts of nanoenergetics is described. The preparation and characterization of two totally different compositions is detailed. In one example, nanostructured aerogel and xerogel composites of sol-gel iron (III) oxide and ultra fine grained aluminum (UFG Al) are prepared, characterized, and compared to a conventional micron-sized Fe{sub 2}O{sub 3}/Al thermite. The exquisite degree of mixing and intimate nanostructuring of this material is illustrated using transmission and scanning electron microscopies (TEM and SEM). The nanocomposite material has markedly different energy release (burn rate) and thermal properties compared to the conventional composite, results of which will be discussed. Small-scale safety characterization was performed aerogels and xerogels of the nanostructured thermite. The second nanostructured energetic material consists of a nanostructured hydrocarbon resin fuel network with fine ammonium perchlorate (NH{sub 4}ClO{sub 4}) oxidizer present.

Journal ArticleDOI
TL;DR: In this paper, the authors show that ZnO is a promising semiconductor candidate for flexible electronics, because thin film transistors can be fabricated at room temperature with higher mobility (> 1 cm2/V-s) and high on/off ratio (> 104).
Abstract: In flexible electronics, plastic substrates can limit processing temperatures to less than 100° C. Consequently, most semiconductors, including amorphous silicon, may be incompatible with temperature-sensitive plastic substrates. While organic semiconductors may seem well suited to this particular application niche, their stability is questionable and their mobility is often low (∼0.1 cm2/V-s). In this paper we show that ZnO is a promising semiconductor candidate for flexible electronics, because thin film transistors can be fabricated at room temperature with higher mobility (> 1 cm2/V-s) and high on/off ratio (> 104).

PatentDOI
TL;DR: A method for forming group III-N articles includes the steps of providing a single crystal silicon substrate, depositing a zinc oxide (ZnO) layer on the substrate, and depositing another single crystal group III N layer on ZnO layer as mentioned in this paper.
Abstract: A method for forming group III-N articles includes the steps of providing a single crystal silicon substrate, depositing a zinc oxide (ZnO) layer on the substrate, and depositing a single crystal group III-N layer on the ZnO layer. At least a portion of the group III-N layer is deposited at a temperature of less than 600° C.

Journal ArticleDOI
TL;DR: In this paper, the authors present an integrated device which combines both fluidic channels and optical waveguides, which opens new opportunities in bio- and chemical sensing. And they report the fabrication of optical waveguide within the same substrate, which is a major step towards the integration of sensing capabilities within microfluidic networks.
Abstract: This paper presents dramatic improvements in the micro-fabrication of three-dimensional microfluidic channels and high-aspect ratio tunnels within the bulk of a fused silica substrate. We also report the fabrication of optical waveguides within the same substrate, which is a major step towards the integration of sensing capabilities within microfluidic networks. This integrated device, which combines both fluidic channels and optical waveguides, opens new opportunities in bio- and chemical sensing. The flexibility of the improved manufacturing process offers substantial new design capabilities, especially for single channel probing and massively parallel processing and sensing.

Journal ArticleDOI
TL;DR: In this article, several MEMS applications of poly-SiGe are discussed: thermal applications, the application as a capping layer for MEMS wafer-level packaging and the use as MEMS structural layer for processing MEMS devices on top of CMOS.
Abstract: In this overview article several MEMS applications of poly-SiGe are discussed: thermal applications, the application as a capping layer for MEMS wafer-level packaging and the use as MEMS structural layer for processing MEMS devices on top of CMOS. For all these applications also different deposition processes have been developed: chemical vapor deposition at reduced pressure (RPCVD), at low pressure (LPCVD) and with plasma enhancement (PECVD). Special techniques to reduce the processing temperature to the absolute minimum are reviewed as well: the use of hydrogenated microcrystalline SiGe, of metal-induced crystallization and of laser annealing. The latter methods are important when one wants to process SiGe MEMS above advanced CMOS with low-permittivity dielectrics.

Journal ArticleDOI
TL;DR: In this article, basic criteria necessary for the synthesis of a variety of oxides in the combustion mode, and defined optimum conditions for the production of high-surface area, well-crystalline nano-powders of desired phase composition and purity.
Abstract: Based on the analysis of extensive experimental data, we have formulated basic criteria necessary for the synthesis of a variety of oxides in the combustion mode, and defined optimum conditions for the production of high-surface area, well-crystalline nano-powders of desired phase composition and purity. Also, for the first time, detailed chemical mechanisms of interaction for various systems are identified, outlining specific roles of different fuels, oxidizers and thermal conditions

Journal ArticleDOI
TL;DR: In this article, HfO 2 thin films were grown by atomic layer deposition on Si, Ge, GaAs and GaN substrates, using Hf(O t Bu) 2 (mmp) 2 and HfCl 4.
Abstract: HfO 2 thin films were grown by atomic layer deposition on Si, Ge, GaAs and GaN substrates, using Hf(O t Bu) 2 (mmp) 2 and HfCl 4 . The results show that this combination of precursors promotes a conformal and smooth growth of HfO 2 films on all substrates. As grown films in the thickness range of 10–20 nm have the same electronic density and smooth surfaces. Films 20 nm thick are polycrystalline with the monoclinic structure, whereas the crystallized fraction in the 10 nm thick layers is much lower. The HfO 2 /Ge interface is remarkably sharp. The dielectric constant of the HfO 2 films is 15. Low density of interface states and oxide fixed charges are obtained for the films grown on Si. The optimization of the HfO 2 interface with the other substrates requires more effort.

Journal ArticleDOI
TL;DR: In this article, various types of configurations formed in face-centered cubic (fcc) and bodycentered cubic structures by two interacting, non-coplanar, dislocation segments of various orientations are examined and discussed.
Abstract: The various types of configurations formed in face-centered cubic (fcc) and body-centered cubic (bcc) structures by two interacting, non-coplanar, dislocation segments of various orientations are examined and discussed. The focus is on junction formation and on a particular interaction, the collinear interaction, which deserves much more attention than paid up to now.

Journal ArticleDOI
TL;DR: In this paper, new developments in polyester film substrates for OLED displays have been described, which are well-known substrate for a wide range of electronic applications, such as computer vision and medical applications.
Abstract: Polyester films are well-known substrates for a wide range of electronic applications. This contribution will describe new developments in polyester film substrates for OLED displays.

Journal ArticleDOI
TL;DR: In this article, spectral sensitization of apparent quantum efficiency (AQE) and J-V analysis was performed using five different sources: white, blue, red or no light, and the results indicated little dependence of series resistance or diode quality factor on the illumination spectrum.
Abstract: Photoconductive CdS (PC-CdS) in CdS/CdTe solar cells from five different sources is investigated using spectral sensitization of apparent quantum efficiency (AQE) and J-V analysis. Red bias light significantly enhances the blue AQE, commonly leading to AQE>1 below 550 nm, and blue bias light enhances the red AQE, but to a much smaller extent. These enhancements are more pronounced with increasing forward bias, after stress and in devices with intentionally Cu-doped CdS. This behavior is observed to some degree in all devices with CdS, but is absent in cells without CdS. These effects are consistent with blue light, either ac monochromatic or dc bias, increasing the CdS conductivity. This causes an increase in the field and depletion width in the CdTe to maintain balanced space charge, leading to increased collection of carriers from the CdTe. The CdS conductivity modulation can also change the AQE due to a change in equivalent circuit resistance. Analysis of J-V data measured with white, blue, red or no light indicates little dependence of series resistance or diode quality factor on the illumination spectrum. Thus, the PC-CdS resistance has little effect on the solar cell J-V performance, but does influence AQE.

Journal ArticleDOI
TL;DR: In this paper, the fundamental physical mechanisms determining the dispersion properties of optical crystal fibers guiding by either total internal reflection or photonic bandgap effects are discussed, and a number of examples from recent modeling and experimental work serve to illustrate their general conclusions.
Abstract: The dispersion, which expresses the variation with wavelength of the guided-mode group velocity, is one of the most important properties of optical fibers. Photonic crystal fibers (PCFs) offer much larger flexibility than conventional fibers with respect to tailoring of the dispersion curve. This is partly due to the large refractive-index contrast available in silica/air microstructures, and partly due to the possibility of making complex refractive-index structures over the fiber cross section. We discuss the fundamental physical mechanisms determining the dispersion properties of PCFs guiding by either total internal reflection or photonic bandgap effects, and use these insights to outline design principles and generic behaviours of various types of PCFs. A number of examples from recent modeling and experimental work serve to illustrate our general conclusions.