The light out-coupling potential of introducing a semitransparent Ag layer between the anode and the organic layer stack of monochrome bottom-emitting organic light emitting diodes (OLED) is examined. Red and green phosphorescent as well as deep-blue fluorescent resonant-cavity OLED (RC-OLED) comprising a semitransparent Ag layer are processed by means of organic vapor phase deposition (OVPD). An enhancement of the luminous efficiency of up to 81% can be observed.

The impressive efficiency enhancement can be explained by a reduced formation of substrate modes in combination with a strong narrowing of the emission spectrum leading to an increased true luminous efficiency.

We developed an optimized inductively coupled plasma (ICP) etching process to produce GaAs pyramidal corrugated quantum well infrared photodetector focal plane arrays. A statistically-designed experiment was performed to optimize the etching parameters. The resulting parameters are discussed in terms of the effect on the etching rate and profile. This process uses a small amount of mask corrosion and the control of the etching mask gap to give a 45-50 degree V-groove etching profile, which is independent on the crystal orientation of GaAs. In the etching development, scanning electron microscope (SEM) was used to observe the surface morphology and the pattern profile. In addition, X-ray photoelectron spectroscopy (XPS) was utilized to obtain the elemental composition and the contamination of the etching surface. It is found that extremely small stoichiometric change and surface damage of the etching surface can be achieved while keeping relatively high etching rate and ~45 degree V-groove etching profile. This etching process is applied to the fabrication of pyramidal C-QWIP FPAs, which is expected to have better performance than the regular prism-shaped C-QWIPs according to electromagnetic (EM) modeling. The expected results will be verified by optical and electrical measurements. In addition to infrared detectors, this process technology can also be applied to GaAs V-groove solar cell, quantum wire light-emitting diodes, quantum wire lasers, and other GaAs –based devices.

Transparent p-n hetero-junction diodes are fabricated using, p-type NiO and n-type ZnO thin films deposited onto a Pt/Ti/glass substrate utilizing RF sputtering technique. The prepared hetero-junctions are studied for the structural, electrical and optical properties and the effect of post-deposition annealing is investigated through I-V measurements and XRD analysis. The as deposited hetero-junction is found to be giving ohmic behaviour while with post-annealing treatment it result in rectification with a ratio of forward-to-reverse current as high as 15 in the range -1.0 to 1.0 V. Forward threshold and the reverse breakdown voltages are found to be about 0.5 and -2.7 V, respectively. The forward-bias I-V characteristics are dominated by the flow of space-charge-limited current with an optical transmission of above 50 % in the visible region important for the transparent electronic device fabrication.

In this work we present preliminary calculations and simulations to demonstrate feasibility of programming a nanoscale Phase Change Random Access Memory (PCRAM) cell by means of a silicon nanowire ballistic transistor (SNWBT). Memory cells based on ballistic transistors bear the advantage of having a small size and high-speed operation with low power requirements. A one-dimensional MOSFET model (FETToy) was used to estimate the output current of the nanowire as a function of its diameter. The gate oxide thickness was 1.5 nm, and the Fermi level at source was set to -0.32 eV. For the case of V DS = V GS = 1 V, when the nanowire diameter was increased from 1 to 60 nm, the output power density dropped from 109 to 106 W cm-2 , while the current increased from 20 to 90 μA. Finite element electro-thermal analysis were carried out on a segmented cylindrical phase-change memory cell made of Ge2Sb2Te5 (GST) chalcogenide, connected in series to the SNWBT. The diameter of the combined device, d, and the aspect ratio of the GST region were selected so as to achieve optimum heating of the GST. With the assumption that the bulk thermal conductivity of GST does not change significantly at the nanoscale, it was shown that for d = 24 nm, a ‘reset’ programming current of I D = 80 μA can heat the GST up to its melting point. The results presented herein can help in the design of low cost, high speed, and radiation tolerant nanoscale PCRAM devices.

The lead-salt epitaxial membrane embedded with two dimensional hexagonal air holes lattice array was used to develop the mid-infrared (mid-IR) photonic crystal surface emitting laser. For the initial proof-of-concept research work, we demonstrated intensive photonic crystal coupled mid-IR vertical light emissions from the designed structure under cryogenic temperature range. In order to realize room temperature operation, we modified the photonic bands structure, aligned the photonic crystal coupled mode with the gain spectrum of active material at 300 K. As a result, under pulsed mode optical excitation, multi-mode room temperature mid-IR photonic crystal lasing emissions were achieved at wavelength ∼3.5 μm recently. With further optimization, a practical lead-salt continuous-wave operating room temperature surface emitting photonic crystal laser is anticipated soon, and this will explore promising applications in a wide variety of fields.

The deformation behaviour of the ζ (zeta) phase in the Fe-Zn system has been investigated via room-temperature compression tests of single-crystal micropillar specimens prepared by the focused ion beam method. Trace analysis of slip lines indicates that {110} slip occurs for the specimens investigated in the present study. Although the slip direction has not been uniquely determined, comparison of Schmid factors and yield stress values suggests that the slip direction might be <1 $\overline 1 $ 2>, which is inconsistent with the easiest slip system {110}[001] predicted on the basis of the primitive Peierls-Nabarro model.

A novel technique combining both atomic force microscopy (AFM) and scanning electron microscopy (SEM) is used to test the mechanical properties of densely-packed graphene oxide (GO) paper. Individual beams of GO paper with variable widths were prepared using focussed ion beam (FIB) microscopy and tensile tested to failure using the AFM while observing with SEM. A variation in the tensile strength of the GO paper beams up to 64.8 MPa was recorded in the vacuum testing condition. An increase in breaking stress of GO paper with decreasing sample width was determined and proposed as being due to fewer defects present in GO beams of smaller width.

We analyze the interplay between anomalous transport and conversion reaction kinetics in mesoporous materials functionalized with catalytic groups. Of primary interest is functionalized mesoporous silica containing an array of linear pores with diameters tunable from 2-10 nm, although functionalization can produce smaller effective diameters, d. For d < 2 nm, transport and specifically passing of reactant and product species within the pores can be strongly inhibited (single-file diffusion). The distribution of catalytic groups can also vary depending on the synthesis approach. We apply statistical mechanical modeling (utilizing spatially discrete stochastic lattice-gas models) to explore the dependence of reactivity on the extent of inhibition of passing of species within the pore, as well as on the distribution of catalytic sites.

The mechanical enhancement of polymers when clay nanoparticles are dispersed within it depends on factors over various length scales; for example, the orientation of the clay platelets in the polymer matrix will affect the mechanical resistance of the composite, while at the shortest scale the molecular arrangement and the adhesion energy of the polymer molecules in the galleries and the vicinity of the clay-polymer interface will also affect the overall mechanical properties.

In this paper, we address the challenge of creating a hierarchal multiscale modelling scheme to traverse a sufficiently wide range of time and length scales to simulate clay-polymer nanocomposites effectively. This scheme varies from the electronic structure (to capture the polymer – clay interactions, especially those of the reactive clay edges) through classical atomistic molecular dynamics to coarse-grained models (to capture the long length scale structure).

Such a scenario is well suited to distributed computing with each level of the scheme allocated to a suitable computational resource. We describe how the e-infrastructure and tools developed by the MAPPER (Multiscale Applications on European e-Infrastructures) project facilitates our multiscale scheme. Using this new technology, we have simulated clay-polymer systems containing up to several million atoms/particles. This system size is firmly within the mesoscopic regime, containing several clay platelets with the edges of the platelets explicitly resolved. We show preliminary results of a “bottom-up” multiscale simulation of a clay platelet dispersion in poly(ethylene) glycol.

Dust originated from the iron and steelmaking containing undesirable compounds are not completely recycled because affects the process efficiency. These types of dust represents an economical lost as a consequence of values contents. However, dust have been characterized physically and chemically in order to study their potential environmental applications, as the removal of arsenic in wastewater. The results shows that dust have a superficial specific area between 16 and 20 m2/g, values considered high, typical of a material with adsorbent properties. Representative results of different tests adsorption of arsenic in the material described indicate that it is possible to reduce the arsenic levels in up to 95% from an initial concentration of 1 mg/L of total arsenic. The results indicate that the iron and steelmaking wet dust may represent a new option as material for the removal of heavy metals in water treatment.

Current-matching between junctions in a multi-junction photovoltaic device is fundamental for its performance prediction: the measurement of the spectral response of each junction provides a valuable information to optimize the device performance. Various aspects make spectral response measurements of such devices particularly challenging. In this work these aspects are analysed theoretically and guidelines to avoid their impact in the experimental practice are given.

Bi-layer material systems are found in various engineering applications ranging from nanoscale components, such as thin films in circuit boards, to macroscale structures, such as adhesive bonding in aerospace and civil infrastructure. They are also found in many natural and biological materials such as nacre or bone. The structural integrity of a bi-layer system depends on properties of both the interface and the constitutive materials. In particular, interfacial delamination has been observed as a major integrity issue. Here we present a multiscale model, which can predict the macroscale structural behavior at the interface between organic and inorganic materials, based on a molecular dynamics (MD) simulation approach combined with the metadynamics method used to reconstruct the free energy surface (FES) between attached and detached states of the bonded system. We apply this technique to model an epoxy-silica system that primarily features non-bonded and non-directional van der Waals and Coulombic interactions. The reconstructed FES of the epoxy-silica system derived from the molecular level is used to quantify the traction-separation relation at epoxy-silica interface. In this paper, two different approaches in deriving the traction-separation relation based on the reconstructed FES are described. With the derived traction-separation relation, a finite element approach using cohesive zone model (CZM) can be implemented such that the structural behavior of epoxy-silica interface at the macroscopic length scale can be predicted. The prediction from our multiscale model shows a good agreement with experimental data of the interfacial fracture toughness. The method used here provides a powerful new approach to link nano to macro for complex heterogeneous material systems.

Olivine lithium manganese phosphate, LiMnPO4 is a promising cathode material for high energy and safe lithium ion batteries. However, LiMnPO4 possesses excessively poor electrochemical activity, compared to conventional cathode materials. To enhance the electrochemical activity, we have synthesized LiMnPO4/multi-walled carbon nanotube (MWCNT) composites by employing an in-situ sol-gel method. The LiMnPO4/MWCNT composites were investigated by utilizing X-ray diffraction, thermogravimetric analysis, scanning electron microscope, transmission electron microscope, and galvanostatic charge-discharge cycling. The LiMnPO4 showed a particle size of ca. 50 nm and capacity of 102 mAh/g at 0.1 C without C.V. charging mode. This study demonstrated that the electrochemical activity of LiMnPO4 was significantly affected by not only pH and the amount of a chelating agent but also unreacted Mn2+. This is the first report analyzing the existence and effects of unreacted Mn2+ in LiMnPO4 synthesized by a sol-gel method.

Bi1.5Zn1Nb1.5O7 (BZN) epitaxial thin films were prepared on Al2O3with a double ZnO buffer layer by pulsed laser deposition. The pole figure analysis and reciprocal space mapping revealed the single crystalline nature of the thin film. The sharp intense spots in the SAED pattern also indicates the highly crystalline nature of BZN thin film. The electrical properties of the as deposited thin films were investigated by patterning an inter digital capacitor (IDC) structure on BZN. A high tunability was observed in this epitaxially grown thin films.

Gold nanoparticles (GNPs) with precisely controlled near infrared (NIR) absorption were synthesized by one-step reaction of chloroauric acid and sodium thiosulfate. The NIR absorption wavelengths and average particle size increase with increasing molar ratio of HAuCl4/Na2S2O3. The as-synthesized GNPs consist of different shape and size, including small spherical gold colloids and larger non-spherical gold crystals. The GNPs with good chemical and optical stability only form in a suitable range of the HAuCl4/Na2S2O3 molar ratio. High molar ratio of HAuCl4/Na2S2O3 reduces GNPs stability due to Ostwald ripening. Chitosan coating improves particle stability and allows these GNPs effective ablation for esophageal adenocarcinoma under low power NIR laser radiation.

Atmospheric microplasma has been intensively studied for various application fields, since this technology has features shown here: generated around only 1 kV under atmospheric pressure,discharge gap of only 10 to 100mm,dielectric barrier discharge. Low discharge voltage atmospheric plasma processis an economical and effective solution forvarious applications such as indoor air control including sterilization, odor removal, surface treatment, and would be suitable for plasma-life science field such as medical application.

In thispaper, the basic study for plasma-life science will be presented. One life science application of microplasma is “sterilization”. The sterilization process was carried out with active species generated between themicroplasmaelectrodes.The active species were observed by emission spectrometry. The spectra showed the existence of active species, and the microplasma had typical characteristics of non-thermal plasma. Sterilization of E. coli was confirmed after microplasma treatment with Ar gas. The bacteria shape was changed after the microplasma process. The other application is “Surface treatment” by long life active species of materials which used for the medical field. The targets are glass, polymer film and others could be also possible.

The process is known as remote microplasma sterilization method. Microplasma generated by both air and Ar are effective for sterilization. Observation by the SEM images shows the E. coli had a shrunked shape after the microplasma treatment.

The contact angle of a water droplet on the polymer surface was measured to estimate its hydrophilicity. The relation between the contact angle and treatment time was investigated. Contact angle decreased from 75.6° to 45.6° after 10 s of treatment.

In this work we have studied the importance of thermal effects on the structural and transport properties of Ag atomic-size nanowires (NWs) generated by mechanical stretching. Our study involve time-resolved atomic high resolution transmission electron microscopy imaging and quantum conductance measurement using an ultra-high-vacuum mechanically controllable break junction combined with quantum transport calculations. We have observed drastic changes in conductance and structural properties of Ag NWs generated at different temperatures (150 and 300 K). By combining electron microscopy images, electronic transport measurements and theoretical modeling, we have been able to establish a consistent correlation between the conductance and structural properties of Ag NWs. In particular, our study has revealed the formation of metastable rectangular rod-like Ag wires along the [001] crystallographic direction.

A reactive molecular dynamics simulation study on the structure, energetics, and chemistry of alkanethiolated gold cluster is presented. Through very recent reactive molecular dynamics force-fields developed by Järvi et al. [1], chemical reactions of alkanedithiolates and star-like shape gold nanoparticles are studied throughout octanedithiolates and stellated cuboctahedral gold clusters models [2] at room temperature. Structure, energetics, reactants, and some products of the reactions are preliminarily analyzed up to 25 ps. In general, preliminary results of this work are in agreement with those reported in the review by Love et al. [3].

Synchrotron X-ray topography (SXRT) of various geometries has been successfully utilized to image c+a dislocations in 4H-SiC crystals. Although molten potassium hydroxide(KOH) can be used to reveal the location of such dislocations, it is not possible to determine their senses or their Burgers vector magnitude. A simple, non-destructive method has been proposed to determine the Burgers vector of these c+a dislocations called the ray tracing simulation, which has been successfully implemented previously in revealing the dislocation sense and magnitude of micropipes, closed-core threading screw dislocations (TSDs) and threading edge dislocations (TEDs) in 4H-SiC. In this paper, grazing incidence topography is performed using the monochromatic beam for the horizontally cut wafers to record pyramidal reflections of 11-28 type. Ray tracing simulation has been successfully implemented to correlate the simulated images with experimental images which are discussed in the paper.

The Seebeck coefficient, electrical resistivity, thermal conductivity and Hall coefficient of FeSbx (x = 2.04, 2.00, and 1.96) nanocomposites hot pressed at 300 °C were measured. The power factor of FeSb1.96 was increased by 105% compared to FeSb2. Hall coefficient measurements revealed a decreased carrier concentration and increased mobility in FeSb1.96 with an overall enhancement in ZTof 45% in FeSb1.96 .