Group II-VI narrow band gap compounds CdTe ZnCdTe and CdSeTe are known as the most suitable semiconductor materials for the room temperature gamma- and X-ray radiation detectors. In this work we investigated electronic properties of a quaternary compound ZnCdSeTe. Cl Cu Pr Er and oxygen doped host materials were synthesized from the grinded mixture of 6N purity ZnTe CdTe and CdSe by the help of CdCl2 flux. Precautions were applied to achieve an uniform doping and high quality of the crystal surfaces. Residue phases after the thermal treatments were removed by the help of a vacuum annealing. It was found that Zn increases a substitutional solubility of dopants in ZnCdSeTe and thus promotes optoelectronic properties of the ZnCdSeTe alloy. Cl substitutes Te whereas Cu and rare earth elements substitute Zn in ZnCdSeTe. Fabricated polycrystalline samples showed a high performance from NIR via VIS and UV to X-ray band. High stability good linearity and performance of samples was measured under X-ray excitation of Cu Kα 1.54056 Å at 40 kV.

The wrinkling of a 50:50 blend of a high molecular mass (Mn = 990kg/mol) and low molecular mass (Mn = 1.3 kg/mol) polystyrene (PS)film is studied as a function of annealing temperature and film thickness.Both thermal and mechanical wrinkling are utilized to elucidate the apparentmodulus of these PS blend films. The PS blend shows a modulus comparable tothe high molecular weight PS, ≈ 3.2 GPa for mechanical wrinkling at ambientand thermal wrinkling for T ≤ 50 °C. A sharp decrease in the apparentmodulus of the film occurs when thermal wrinkling occurs at 60 °C or higher.The calculated modulus in this case is 0.5 GPa, which is significantly belowthe modulus determined the neat PS for either Mn when thermallywrinkled at T > 60 °C. This behavior is attributed to a combination ofsurface segregation of the low molecular weight PS as well as the largedifference in bulk glass transition temperature (Tg) of eachcomponent. During thermal wrinkling, the high Mn PS vitrifiesfirst, while the surface containing primarily low Mn PS isrubbery; this leads to only the underlayer of PS wrinkling initially andselection of a shorter wavelength due to the effective thickness. Theincreased thermally induced stresses during cooling when the low Mn PS is vitrified do not change the selected wavelength andinstead only leads to an increase in the wrinkle amplitude. These resultsillustrate a potential method to modulate the wrinkle wavelength withoutchanging the overlayer, which could be useful for patterningapplications.

In this work, pulsed electron deposition was used to prepare thin films of ITO on plastic substrates. These films were used as electrodes for organic photovoltaic devices to determine the feasibility of using PED deposited ITO as electrodes. ITO films deposited on plastic showed optical transmission values as high as 85% for films deposited at high pressures. Films deposited on plastic substrates were further used to prepare a test organic solar cell, with ITO as the bottom electrode. The device performance was seen to depend on the quality of the ITO electrode, and the ITO film deposited at the lowest oxygen pressure was found to be the best electrode for the organic photovoltaic device.

In this work we present preliminary results from molecular dynamics simulations for carbon nanotubes serpentine dynamics formation. These S-like nanostructures consist of a series of parallel and straight nanotube segments connected by alternating U-turn shaped curves. Nanotube serpentines were experimentally synthesized and reported in recent years, but up to now no atomistic simulations have been carried out to address the dynamics of formation of these structures. We have carried out fully atomistic molecular dynamics simulations in the framework of classical mechanics with a standard molecular force field. Multi-million atoms structures formed by stepped substrates with a carbon nanotube (about 1 micron in length) placed on top of them have been considered in our simulations. A force is applied to the upper part of the tube during a short period of time and then turned off and the system set free to evolve in time. Our results showed that these conditions are sufficient to form robust serpentines and validate the general features of the ‘falling spaghetti mechanism’ previously proposed to explain their formation.

We demonstrate series-connected tandem photovoltaic cells consisting of hydrogenated amorphous silicon (a-Si:H) solar cells and polymer-based organic photovoltaic (OPV) cells. One of the limiting factors of a-Si:H solar cells is their narrow absorption spectrum as compared with that of crystalline silicon solar cells. In order to overcome this limitation, we fabricated a hybrid tandem solar cell by employing a solution-processed OPV subcell based on a low bandgap semiconducting polymer onto the a-Si:H subcell. It was found that the interfacial property of the hole transporting intermediate layer between the subcells strongly affects the photovoltaic property of the tandem cells. By using MoO3 as an efficient hole transporting intermediate layer instead of the conventional conducting polymer, we obtained the power conversion efficiency of 1.84% and the open-circuit voltage (V OC) of 1.50 V which corresponds closely to the sum of the V OCs of the subcells.

Individually propulsive catalytic Janus particle swimmers are observed to self-assemble into aggregate swimmers with a wide variety of translational and rotational velocities. The trajectory for a given doublet is shown to be determined by the frozen in relative orientation of the particles. The new swimmers suggest applications as transport and mixing devices, and will allow study of the interplay between propulsion and Brownian phenomena. Furthermore this random assembly process can be controlled using external magnetic fields to orientate individual ferromagnetic swimming particles so as to favor the production of swimmers with particular desirable configurations resulting in linear trajectories. This approach also produces swimmers that can be orientated, and so “steered” by external fields.

The present study investigates systematically, how the electrical properties of thin films consisting of silicon nanoparticles are affected by an organic monolayer coating the particles. Therefore, films of as-prepared silicon nanoparticles with a size of about 23 nm as well as freshly etched ones, both terminated with hydrogen, are compared with films of silicon nanoparticles functionalized with different 1-alkenes. It is found that the activation energy of the electron transport through the nanoparticle films scales with the thickness and permittivity of the respective organic monolayer.

We report on the use of La2O3 (LO) as a capping layer for ferroelectric-gate thin-film transistors (FGTs) with solution-processed indium-tin-oxide (ITO) channel and Pb(Zr,Ti)O3 (PZT) gate insulator. The fabricated FGT exhibited excellent performance with a high “ON/OFF” current ratio (ION/IOFF ) and a large memory window (∆Vth ) of about 108 and 3.5 V, respectively. Additionally, a significantly improved data retention time (more than 16 hours) as compared to the ITO/PZT structure was also obtained as a result of good interface properties between the ITO channel and LO/PZT stacked gate insulator. We suggest that the LO capping layer acts as a barrier to prevent the interdiffusion and provides atomically flat ITO/LO/PZT interface. This all-oxide FGT device is very promising for future ferroelectric memories.

Traditionally, the synthesis of resorcinol formaldehyde (R/F) aerogels consists of a 2-step (base/acid catalysis) polycondensation reaction. Since the acid catalyst in the reaction controls the gelation time, the replacement of the acid catalyst with a non-ionic photo-acid generator decreased the gelation time from hours, down to a few minutes at room temperature using a UV light source. The reaction rate was not only fast, but the liquid precursor was stable for several hours prior to UV exposure. After drying, the resulting aerogel porosity was characterized by scanning electron microscopy (SEM) and confirmed the internal structure of the aerogel was similar to the original R/F pore structures. This paper will discuss the modifications made to the traditional R/F formulation, as well as the benefits of a fast gelation time for aerogel casting applications such as thin films, cylinders, and solid and hollow microspheres.

We show that nonreciprocal Bloch-like oscillations can emerge in passive optical waveguide arrays with linearly growing effective index in the absence of loss or gain. Spectral asymmetry, a difference in propagation constants and Bloch oscillation periods in opposite propagation directions, are established by imposing different vertical spatial index gradients at the substrate/core, and core/cover interfaces in the presence of transverse magnetization. A model system consisting of an array of transversely magnetized asymmetric garnet/silicon-on-insulator waveguides is presented.

A prerequisite for modelling the growth of diamond by CVD is knowledge of the identities and concentrations of the gas-phase species which impact upon the growing diamond surface. Two methods have been devised for the estimation of this information, and have been used to determine adsorption rates for Cx Hy hydrocarbons for process conditions that experimentally produce single-crystal diamond, microcrystalline diamond films, nanocrystalline diamond films and ultrananocrystalline diamond films. Both methods rely on adapting a previously developed model for the gas-phase chemistry occurring in a hot filament or microwave plasma reactor. Using these methods, the concentrations of most of the Cx Hy radical species, with the exception of CH3, at the surface have been found to be several orders of magnitude smaller than previously believed. In most cases these low concentrations suggest that reactions such as direct insertion of C1Hy (y = 0-2) and/or C2 into surface C–H or C–C bonds can be neglected and that such species do not contribute significantly to the diamond growth process in the reactors under study.

In the current work, we present a detailed study on the material properties of the CIGS layers, fabricated on top of the CMOS chips, and compare the results with the fabrication on standard glass substrates. Almost identical elemental composition on both glass and CMOS chips (within measurement error). From X-ray diffraction measurement, except two peaks from the Si <100> substrate, the diffraction peaks from CIGS solar cell CMOS chip and that on glass substrate coincide for all three temperatures. Helium ion microscope images of the cross-section and top view of the CIGS layers, shows that the grain size is suitable for high efficiency solar cells.

Perovskite-type transition metal oxides have great potential as storage material in resistive random-access memory (RRAM) devices. Typical non-volatile memory cells are realized in metal-insulator-metal (MIM) stacks with insulator thicknesses of few nanometers. We report on the investigation of single-crystal SrTiO3 to understand the role of volume and interface real structure for the electrical conductivity in such materials. Conductivity in SrTiO3 single crystals was established by a reducing high vacuum (HV) annealing introducing charged oxygen vacancies acting as donor centers. Titanium electrodes are evaporated on both crystal faces to obtain an MIM element.

Equilibrium geometries and cohesion energies of Ag0.94Cd0.06, Ag0.94In0.06, Au0.94Cd0.06, and Au0.94In0.06 solid alloys have been studied from the first principles within the Density Functional Theory using ab initio pseudopotentials. Equilibrium geometries are obtained by total energy minimization method using the Local Density Approximation and Generalized Gradient Approximation methods. Optical functions are calculated within the independent particles picture. We report essentially different behavior of Cd and In impurity atoms in Au- and Ag-based alloys: the aggregated (or quasi aggregated) phases in In-containing alloys are expected in contrast to the alloys with Cd atom where homogeneous impurity distribution over the bulk should dominate. Study of optical spectra in Ag0.94Cd0.06 and Au0.94Cd0.06 alloys indicate that optical losses in visible and near ultraviolet spectral range remarkably increase at bigger Cd concentrations. In ultraviolet spectral region redistribution of optical oscillator strengths results in both increase and decrease of optical losses in selected spectral regions.

The study of the irradiation effects on titanium surfaces in oxidizing environment using multi-charged Argon ions in the MeV range shed into light the following points:-Significant oxide film thickening for the film grown at 500°C under irradiation at 4 and 9 MeV, by comparison with the TiO2 rutile film grown under same environmental conditions without irradiation;-Formation of large round –shaped craters, of diameter approaching 200 nanometers, at the titanium surface under irradiation at 500°C provided that the environment is enough oxidizing or provided that the metal surface is covered by a sufficiently thick oxide film.

Practically, and for the present system, the superficial craterization is observed if the thickness of the superficial oxide is equal to twice that of the native oxide (~3 nm).

Decorative features on a Greek red-figure stamnos in the collection of the Worcester Art Museum were examined using Reflectance Transformation Imaging (RTI) and scanning laser confocal microscopy. These two surface examination tools helped to answer questions relating to the decorative process, particularly the tools and techniques that Attic painters used to create the so-called glossy black “relief lines” and “relief dots.” This research also incorporated fabricated mock-ups to help understand the ancient technology. It was determined that the relief line was not produced by an extruded method, but with a brush made of one or very few hairs, an idea first proposed by Gérard Seiterle in 1976 and termed Linierhaar. It was observed that not one but two distinct types of relief lines exist: the “laid” line (proposed by Seiterle) characterized by a ridge running through the middle of the line and the “pulled” line (proposed in this paper) which has a furrowed profile. Both line types were reproduced with a Linierhaar. Additionally, relief dots were replicated using a conventional brush. Surface examinations of other red-figure vessels using RTI and the confocal microscope suggest these conclusions apply to vessels of this genre as a whole.

We successfully fabricated a-IGZO TFTs employing a Ti/Cu source/drain (S/D) and SiNx passivation in order to reduce the line-resistance, as compared to most oxide TFTs that use Mo (or TCO) and SiO2 for their S/D and passivation, respectively. Although passivated with SiNx, the TFT exhibits good transfer characteristics without a negative shift. However, the TFT employing a Mo S/D exhibited conductor-like characteristics when passivated with SiNx. Our investigation suggests that the IGZO oxygen vacancies found in the Ti/Cu S/D are controlled, resulting in low concentrations, and so prevent the SiNx-passivated TFT from having a negative shift.