High molecular weight vinyl esters and carbonates based on oligo(ethylene glycol), oligomeric fatty acids and poly(hexamethylene carbonate), as alternatives for potentially cytotoxic acrylate based monomers have been structured by Additive Manufacturing Technologies (AMTs) like Microstereolithography (μ-SLA), Digital Light Processing (DLP) and Two-Photon Induced Photopolymerization (TPIP). With these techniques feature resolutions down to 10 μm (μ-SLA and DLP) or even 200 nm (TPIP) can be obtained.This new class of monomers exhibits LC50 values for cytotoxicity up to two orders of magnitude lower than acrylate references. Beside a high reactivity of the resin, the shrinkage and the mechanical properties of the final part material are another essential parameter. Low molecular weight monomers are very reactive and lead to densely cross-linked materials which suffer from high shrinkage and strains within the cured material. Therefore, mixtures of high molecular weight vinyl esters/carbonates with low molecular weight crosslinkers have been evaluated regarding their photoreactivity and mechanical properties.

Photo active fibers containing dye anchored Nb2O5 nanorods, hole conduction and electron conduction materials were synthesized by the electrospinning technique. A 1.92 cm2 piece of fabric, composed of randomly aligned nanorods, was tested as a photovoltaic device under standard illumination conditions. The solar fabric exhibited an open circuit voltage (V oc) of ˜0.67 V, a short current density (J SC) of 4.77×10-4 mA/cm2, a fill factor (FF) of ˜15%, and an overall photovoltaic conversion efficiency (η) of 4.5×10-7%. This article presents for the first time the application of Nb2O5 in solar fabric.

Atomistic models of amorphous solids enable us to study properties that are difficult to address with experimental methods. We present a study of two amorphous semiconductors with a great technological importance, namely a- Si:H and a-SiN:H. We use first-principles density functional theory (DFT), i.e. the interatomic forces are derived from basic quantum mechanics, as only that provides accurate interactions between the atoms for a wide range of chemical environments (e.g. brought about by composition changes). This type of precision is necessary for obtaining the correct short range order. Our amorphous samples are prepared by a cooling from liquid approach. As DFT calculations are very demanding, typically only short simulations can be carried out. Therefore most studies suffer from a substantial amount of defects, making them less useful for modeling purposes. We varied the cooling rate during the thermalization process and found it has a considerable impact on the quality of the resulting structure. A rate of 0.02 K/fs proves to be sufficient to prepare realistic samples with low defect concentrations. To our knowledge these are the first calculations that are entirely based on first-principles and at the same time are able to produce defect-free samples. Because of the high computational load also the size of the systems has to remain modest. The samples of a-Si:H and a-SiN:H contain 72 and 110 atoms, respectively. To examine the convergence with cells size, we utilize a large cell of a-Si:H with a total of 243 atoms. As we obtain essentially the same structure as with the smaller sample, we conclude that the use of smaller cells is justified.Although creating structures without any defects is important, on the other hand a small number of defects can give valuable information about the structure and electronic properties of defects in a-Si:H and a-SiN:H. In our samples we observe the presence of both the dangling bond (undercoordinated atom) and the floating bond (over-coordinated atom). We relate structural defects to electronic defect states within the band gap. In a-SiN:H the silicon-silicon bonds induce states at the valence and conduction band edges, thus decreasing the band gap energy. This finding is in agreement with measurements of the optical band gap, where increasing the nitrogen content increases the band gap.

Thermal conductivity and electrical resistivity of 1 μm long aluminum nanowires, 75, 100, and 150nm in width and 100nm thick, were measured at room temperature. The method consists of microfabricated electrothermal test devices and a model-based data processing approach using finite-element analysis (FEA). The electrical and thermal properties of the nanowires differ significantly from bulk values while electrical resistivity agrees well with theoretical prediction. Electron transport equation models, which adequately describe the resistivity data, consistently underestimate the thermal conductivity. Incorporating a phonon contribution of ˜ 21 W/m·K to the total thermal conductivity is found to accurately describe the measured values.

In this work we investigated the structural, electrical, and optical properties of titanium dioxide (TiO2) nanotubes (NTs) formed by electrochemical anodization of Ti metal sheets in NH4F+glycerol electrolyte at different anodization voltages (Va) and acid concentrations. Our results revealed that TiO2 NTs can be grown in a wide range of anodization voltages from 10 V to 240 V. The maximum NH4F acid concentration, at which NTs can be formed, decreases with the anodization voltage, which is 0.7% for Va<60V, and decreases to 0.1% at Va =240 V. Glancing angle X-ray diffraction (GAXRD) experiments show that as-grown amorphous TiO2 transforms to anatase phase after annealing at 400 oC, and further transforms to rutile phase at annealing temperatures above 500 oC. Samples grown in 30-120 voltage range have higher crystal quality as seen from anatase (101) peak intensity and reduced linewidth. The electrical resistivity of the NTs varies with Va concentration and increases by eight orders of magnitude when Va increases from 10 V to 240 V. This is consistent with cathodoluminescense studies which showed improved optical properties for samples grown in this voltage range. Optical properties of samples were also studied by low temperature photoluminescence. Temperature dependent I-V and photo-induced current transient spectroscopy were employed to analyze electrical properties and defect structure on NT samples.

The present communication will present the results obtained at CEA/LETI in Grenoble, France, in the frame of an experimental work finalized to directly test the criticalities and chances of this technology row. By means of Closed Space Sublimation (CSS) and Chemical Bath Deposition (CBD) processes, appropriate annealing treatments and specific CdTe-contacting procedures, we reached the state-of-art of this technology with about 15% conversion efficiency under standard illumination conditions in “superstrate” cells configuration both for structures deposited on 3 mm thick low-iron containing sodalime glass (SLG) and Borosilicate glass (BSG).

Large-scale manufacturing of organic light-emitting diode (OLED) panels for lighting and display has been slowed by several manufacturing factors, prominent among which are low throughput due in part to the fine metal mask technology for patterning the red-, green-, and blue-light-emitting pixels and low materials utilization efficiency of the available vacuum deposition technology. To overcome these impediments to low-cost OLED manufacturing, Kodak developed a blanket white-emitting OLED architecture in combination with a pixilated color filter array to eliminate the need for fine metal masks and developed a vacuum deposition technology capable of high deposition rates and high materials utilization efficiency. These developments, taken together, allow much higher throughput and yield on fifth-generation and larger substrates that promise to enable low-cost manufacturing of OLED displays and lighting panels. This paper focuses on the deposition technology Kodak developed, a flash vaporization process that can deliver very high materials utilization efficiency at high deposition rates for small-molecule OLED materials without increasing material decomposition.

We employ spectroscopic ellipsometry in the terahertz (0.2 to 1.5 THz) and the mid-infrared (9 to 50 THz) spectral range for the non-contact, non-destructive optical determination of the free-charge-carrier properties of low-doped Silicon bulk and thin film structures. We find that carrier concentrations as low as 1015 cm−3 in thin films can be unambiguously determined. We envision ellipsometry in the THz spectral range for future non-contact, non-destructive monitoring and control applications.

As a part of the optimization study for achieving the highest possible Hanford and Savannah River Site waste loading into acceptable borosilicate glasses, thirty glass compositions were selected for testing at KRI. These thirty test matrix glasses were designed to augment existing data within the compositional regions of interest with relatively high concentration of Al2O3 between 10 and 20 wt%.

This paper reports experimental data on liquidus temperature (TL) and crystallization behavior of all synthesized glasses as well as durability of quenched and heat-treated glasses. The results of this study will be used to develop glass formulations for specific DOE waste streams to maintain or meet waste loading and/or waste throughput expectations while satisfying critical process and product performance related constraints.

Copper nanoparticle was prepared by liquid phase reduction technique. Cu2+ was reduced to copper particle by adopting different types of reductants. Ascorbic acid (C6H8O6), phosphinic acid (H3PO2), titanium sulfate (Ti2(SO4)3) and sodium borohydride (NaBH4) were chosen as reductant, respectively. The effect of reaction driving force upon the average size of copper particle was investigated in the paper. It can be concluded that there is a firm relationship between the reaction driving force and the average size of copper particle. The average size of copper particle decreases with the increasing of reaction driving force.

The FEBEX in-situ experiment, installed in 1997 at the Grimsel Test Site (GTS, Switzerland) 400 m depth under the Swiss Alps, simulates a high level radioactive waste repository (HLWR) emplaced in granite. Its initial aim was to study the performance of a bentonite engineered barrier but recently, two new boreholes were drilled in the granite to study the possible bentonite colloid formation and their migration in the granite.

This study presents the characterization performed, at the micrometer scale, of the threemain water conductive fractures that were identified on the granite cores extracted from the newboreholes. These fractures are possible pathways for bentonite colloid transport (or retention),may be source of natural colloids and may condition colloid stability. The nuclear ion beamtechniques µ-Particle X-Ray Emission (µPIXE) and Rutherford Backscattering Spectrometry(RBS) were applied for visualizing and quantifying the elemental composition of the fracturessurface and of the surrounding micro-fractures, as support of the bentonite colloid analyses.

We discuss main degradation mechanisms present in nitride based laser diodes operating in 400-440 nm spectral range. We can clearly divide the aging processes into these occurring on the exposed facets of the device and into the bulk phenomena. Surface processes are predominantly connected with photochemical reactions on the laser mirrors and manifest by the formation of the carbon deposits. The nature of these photochemical reactions resembles very closely the mechanism known as Package Induced Failure observed previously in case of 980 nm laser diodes. Degradation involving bulk like effects is much less understood. The experimental results by other group are not sufficient for proposing an unambiguous model of the physical effects involved. In particular, it consists in observation related to dopants diffusion and recombination mechanisms. Magnesium diffusion from the p-type layers into the active layer was proposed as a possible degradation path. However, our study of SIMS profiles in the device subjected to over 8 000 h of electrical stress reveals no visible modification in the Mg profile. The same holds for the hydrogen spatial distribution thus substantially limiting candidates for the diffusion processes. Nevertheless, it seems that the diffusion mechanism is involved in bulk degradation. The claim is supported by two facts: well confirmed stability of the extended defects network in nitride emitters and characteristic square-root time-dependence of the degradation rate.

In this work, we demonstrate the synthesis of cadmium sulfide (CdS) nanoparticles in aqueous solution with MS2 bacteriophages as a biotemplate. Bionanofabrication methods offer unique opportunities for nanomaterials synthesis, where choice of biotemplate can influence the size, shape and function of the produced material. Synthesis reactions are carried out under mild aqueous conditions, and thus hazardous organic solvents, high temperature, and extreme pH can be avoided. The MS2 bacteriophage is a potential template system for bionanofabrication of nanoscale materials due to its size and inherent physical/chemical properties. MS2 capsid proteins can be genetically modified to incorporate functional groups and sequences. Also, genomic RNA in MS2 can be degraded or replaced with other oligonucleotide sequences and still form intact capsids. In this work, we use MS2 for bio-assisted synthesis of CdS nanoparticles and adjust the amount of RNA present in the template to assess biotemplate-nanomaterial property relationships. Produced nanoparticles were probed with several techniques including UV-Vis, photoluminescence and Hi-Res TEM. Optical techniques revealed that CdS nanoparticles with predicated fluorescent properties form in the presence of MS2 and remain stable in aqueous solutions. In fact, MS2-templated CdS nanoparticles were stable at room temperature for several weeks. Presence of RNA in the capsid interior was found to have major impact on the biotemplating process. Hi-Res TEM micrographs verified the presence of nanocrystals and their association with the biotemplate. Bionanofabrication using viral templates holds promise to enable an efficient, controlled and environmentally sustainable synthesis approach for a range of important nanomaterials. The work presented here represents an additional step forward towards those goals.

The characterization of doped regions inside silicon nanowire structures poses a challenge which must be overcome if these structures are to be incorporated into future electronic devices. Precise cross-sectioning of the nanowire along its longitudinal axis is required, followed by two-dimensional electrical measurements with nanometer spatial resolution. The authors have developed an approach to cross-section silicon nanowires and to characterize them by scanning spreading resistance microscopy (SSRM). This paper describes a cleaving- and polishing-based cross-sectioning method for silicon nanowires. High resolution SSRM measurements are demonstrated for epitaxially grown and etched silicon nanowires.

Heterodyne optical feedback on a class B laser is investigated for Scanning Near field Optical Microscopy (SNOM). All-fiberized set-up combining an Er-doped Distributed Feedback (DFB) fiber laser, a pair of pigtailed acousto-optics modulators (AOM) and a shear-force based scanning probe technique has been developed for the simultaneous observation of topography and evanescent light field on integrated optical devices. First demonstration of imaging using this technique is illustrated by characterizing the propagating modes into a rib waveguide at 1.54μm. Comparison between a theoretical model based on beam propagation mode (BPM) simulations and experimental measurements validates the results.

Silver antimony selenide (AgSbSe2) thin films were prepared by heating sequentially deposited antimony sulphide (Sb2S3), silver selenide (Ag2Se) and Ag thin films in close contact with a selenium thin film. Sb2S3 thin film was prepared from chemical bath containing SbCl3 and Na2S2O3, Ag2Se from the bath containing AgNO3 and Na2SeSO3 and Se thin films from an acidified solution of Na2SeSO3, at room temperature on cleaned glass substrates. Ag thin film was deposited by vacuum thermal evaporation. The annealing temperature was varied from 300-390°C in vacuum (∼10−3 Torr) for 1 h. X-ray diffraction analysis showed the films formed at 350 °C was polycrystalline AgSb(S,Se)2 or AgSbSe2 depending on selenium thin film thickness. Morphology of these films was analyzed using Atomic Force Microscopy and Scanning Electron Microscopy. The elemental analysis was done using Energy Dispersive X-ray technique. Optical characterization of the thin films was done by optical transmittance spectra. The electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: Glass/ITO/CdS/AgSbSe2/Ag was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this PV structure showed Voc=370 mV and Jsc=0.5 mA/cm2 under illumination using a tungsten halogen lamp.

Characteristics of strained layer superlattices (SLS) consisting of alternating layers InxGa1-xAs and GaAs1-yPy are examined for use in high efficiency solar cells. The effects of SLS quantum barrier widths on tunneling probability and short circuit current are discussed through analysis of J-V and spectral response measurements. Results indicate a threshold barrier thickness for which tunneling effects are deleterious. Effect of the number of SLS periods incorporated into a p-i-n structure and maximum number of periods are presented through spectral response and CV analysis. It is demonstrated that SLS show increasing responsivity with increasing number of periods due to higher absorption. CV analysis is performed to determine zero bias depletion widths for verifying appropriate number of SLS periods and fully depleted SLS region.

We report on a direct epitaxial growth approach for the heterogeneous integration of high speed III-V devices with Si CMOS logic on a common Si substrate. InP-based heterojunction bipolar transistor (HBTs) structures were successfully grown on patterned Si-on-Lattice-Engineered-Substrate (SOLES) substrates using molecular beam epitaxy. DC and RF performance similar to those grown on lattice-matched InP were achieved in growth windows as small as 15×15μm2. This truly planar approach allows tight device placement with InP-HBTs to Si CMOS transistors separation as small as 2.5 μm, and the use of standard wafer level multilayer interconnects. A high speed, low power dissipation differential amplifier was designed and fabricated, demonstrating the feasibility of using this approach for high performance mixed signal circuits such as ADCs and DACs.

Phase transformations in epitaxial yttrium films grown on (0001)Ti//(0001)Al2O3 Ti-buffered sapphire substrates and hydrogenated for 10 min were characterized using transmission electron microscopy. After hydrogen charging, dense twin lamellae form during α(Y(H))-to-β(YH2) phase transition with twin boundaries predominately parallel to the interface between Y and a substrate. High densities of Shockley partial dislocations are present at the twin boundaries, their glides during phase transformation are responsible for the formation of twin lamellae. Electron diffraction from YH2 phase shows superlattice reflections, which suggests a new type of ordering on octahedral interstitial sites.