Commercially available tenorite (CuO) nanoparticles (NPs) were investigated in particular with respect to their suitability for photovoltaic applications. NPs with a diameter of about 30 nm were step wise annealed up to 1000°C in nitrogen atmosphere. The influence of the annealing treatment on the structural and electronic properties was investigated by Raman, photoluminescence (PL) and photothermal deflection spectroscopy (PDS) as well as X-ray diffraction measurements. Size, shape, and phase of the untreated NPs are analyzed by TEM measurements. The PL and PDS results show a strong increase of the tenorite band edge emission at about 1.3 eV accompanied by a decreasing sub gap absorption with increasing annealing temperature up to 700°C. According to literature, a phase transition from tenorite to cuprite (Cu2O) was expected and observed after annealing at 800°C. Strong cuprite band edge emission at about 2 eV accompanied by very weak defect and possibly tenorite band edge emission was found for samples annealed at 800°C and 1000°C.

In this study, we demonstrate blue organic light-emitting diodes (OLEDs) with a dual emitting layer (EML) configuration consisting of fluorescent and phosphorescent emitting materials. We investigated the influence of dopants on the electrical and optical characteristics of devices when controlling the fluorescent dopant concentration. The current density and luminance of device B doped with 12wt% BCzVBi was 141.6 mA/cm2 and 6582 cd/m2 at 10V, respectively. In addition, a maximum luminous efficiency of 8.11 cd/A, was achieved from device B. The corresponding Commission Internationale de l’E´ clairage (CIExy) coordinates of device D doped with 5wt% BCzVBi were (0.143, 0.255) at 6V.

This report outlines a methodology for reading back different electrical charges, from Non Volatile Memory (NVM) based Flash devices. The charge is stored in the floating gates (FGs) of the transistors. Reading back these charges in the form of logic levels of “1 bit (1b)” and “0 bit (0b)” without deleting the information from the device was the goal. Scanning Capacitance Microscopy (SCM) with ∼50-100 nm spatial resolution was used, to directly probe the charge on Floating Gate Transistor (FGT) channels. Transistor charge values (ON/OFF or “1b/0b”) are measured. Both the sample preparation and SCM probing methods are discussed. The application has been demonstrated with SanDisk based 64 MB NAND Flash memory device.

The purpose of the present paper is to focus on the impact of oxygen gas partial pressure during the sputtering of i-ZnO and ZnMgO on the transient behavior of solar cells parameters when a CBD-ZnS buffer layer is used. Based on electrical characterization of cells, we have observed that the effect of light-soaking is different on J-V characteristics depending on the quantity of oxygen present during the first deposition time of the i-ZnO or ZnMgO layers. In fact, we have noticed that, when cells are prepared with standard i-ZnO, the efficiencies are very low and a pronounced transient behavior is observed. However, when the i-ZnO or ZnMgO is first formed by a few nanometers sputtered layer without any additive oxygen, depending on the thickness of this layer, the transient effects strongly decrease. It is then possible to reach efficiencies quite similar to the CdS reference cells, especially with ZnMgO, without any post-treatments.

Cupric oxide thin films were sputtered onto soda-lime glass slides from a single pre-formed ceramic target using a radio-frequency power supply. The effects of oxygen partial pressure and substrate temperature on the optical, electrical and structural properties of the films were studied. It was found that increasing temperature resulted in increased crystallinity and crystal size but also increased film resistivity. The most conductive films were those deposited at room temperature. Increasing oxygen partial pressure was found to reduce resistivity dramatically. This is thought to be due to higher charge carrier concentrations resulting from increased copper vacancies. Increasing oxygen partial pressure causes an increase in the optical band gap from a minimum of 0.8eV up to a maximum of 1.42eV. Oxygen-rich films display reduced crystallinity, becoming increasingly amorphous with increased oxygen content. These results show that the optical, electrical and structural properties of sputtered cupric oxide films can be controlled by alteration of the deposition environment.

In this investigation, CeO2 analogues, which approximate as closely as possible the characteristics of fuel-grade UO2, were characterised after dissolution under a wide range of conditions. Powdered samples were subject to a range of aggressive and environmentally relevant alteration media with different solubility controls, and reacted at 70 °C and 90 °C. Dissolution kinetics were monitored through analysis of the coexisting aqueous solution. Monolith samples were monitored for development of surface defects such as pores and dissolution pits, in addition to morphological changes at grain boundaries and surface pores upon dissolution under aggressive conditions. The surfaces were analysed using confocal profilometry, vertical scanning interferometry and scanning electron microscopy. Dissolution rates were found to be greatest in low pH solutions and at higher temperatures. Preferential dissolution appears to occur at grain boundaries and on particular grains, suggesting a crystallographic control on dissolution.

We investigate metallic thin films on VO2 and show that the magnitude of the reflected color change in that visible portion of the spectrum as VO2 undergoes the insulating to metallic phase transition can be controlled by changing the type of metal, the thickness of the metal and by patterning the metal at the nano scale. We consider the role of surface plasmas in the metal film and show that in the near infrared, the magnitude of the reflectivity increase for metal coated VO2 films, but decrease for uncoated VO2 thin films. This is explained in the context of Fresnel equations and considering the large change in the imaginary part of the dielectric constant as the VO2 changes state from the insulating to metallic phase.

Iron oxide microspheres possess a wide range of applications in lithium storage batteries, sensors, photocatalysis, environmental remediation, magnetic resonance imaging and drug delivery. The most commonly used method for the preparation of iron oxide microspheres is hydrothermal synthesis. Besides this, other synthetic methods such as co-precipitation, electrostatic self- assembly, microwave and sol-gel have been reported. The reported synthetic methods usually require longer time (2 to 48 hours) and expensive experimental set up. In the present study, a novel low temperature thermal decomposition approach for the synthesis of iron oxide microspheres has been reported. Thermal decomposition of an iron-urea complex ([Fe(CON2H4)6](NO3)3) in a mixture of diphenyl ether and dimethyl formamide at 200 °C for 35 minutes leads to the formation of iron oxide microspheres. The microspheres were characterized using a variety of analytical techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and magnetometry. The XRD results indicated amorphous nature for the as prepared iron oxide, whereas after calcination at 500 °C, crystalline α-Fe2O3 phase is obtained. The SEM images indicated uniform spheres with an average diameter of 1.2 ± 0.3 μm. The DRS results too gave evidence for the formation of α-Fe2O3 on calcination of the microspheres at 500 oC.The field and temperature dependent magnetic measurement results indicated superparamagnetic behavior for the as prepared iron oxide microspheres indicating that the microspheres consist of iron oxide nanoparticles. On the other hand, an antiferromagnetic behavior was observed for the microspheres calcined at 500 °C. The present synthetic method is a novel method to produce magnetic materials with controlled morphologies.

Lead free niobate solid solutions can exhibit piezoelectric properties comparable to that of lead zirconate titanate piezoelectrics in the vicinity of its morphotropic phase boundary (MPB). Here we describe how (Na,K)NbO3 and (Na,K)NbO3-LiTaO3 solid solution thin films can be grown epitaxially by the hydrothermal method at temperatures of 200 °C or below in water and be made ferro- and piezoelectrically active by a simple 2 step post growth treatment.

Here, we present a method for the fabrication of silicon (Si) nanowires and Si nanowire-gold nanoparticles (AuNPs) heterostructures for surface-enhanced Raman scattering (SERS) effect. Branched Si nanowires were grown in atmospheric pressure chemical vapor deposition (CVD) process. Further decoration of these nanowires was achieved by a galvanic deposition of gold followed by annealing procedure. This resulted in Si nanowires-AuNPs heterostructures with controlled size and inter-particle spacing. Furthermore, the fabricated heterostructures were studied for Raman signal enhancement of the low concentration (∼10-6 M) dye (Rhodamine 6G, R6G). It was observed that heterostructuring of SiNWs with AuNPs led to improvement of R6G signals as compared to AuNPs dispersed on flat Si substrate.

We investigated the thermoelectric voltage (TEV) of atomic contacts of nickel (Ni) by using a scanning tunneling microscope. The TEV of nanoscale junctions show fluctuation in stepwise manner. Histogram analysis of TEV observed in the Ni point contact with the conductance of 1.2 G 0 (G 0 = 2e 2/h is the quantum of charge conductance) revealed multiple voltage peaks at larger and smaller values observed at conductance of 2.5 G 0, which showed a single sharp voltage peak. Fluctuation observed in our results suggest that there is transition of the transport channel distribution caused by the thermal motion of Ni atoms.

A thorough understanding of chemistry in extreme environments is a major challenge in experimental as well as theoretical work. With continual improvements in ultrafast optical measurements and new methods for simulations of shock-induced chemistry for timescales approaching a nanosecond, the opportunity is beginning to exist to connect experiments with simulations on the same timescale. In the present work, we compute the optical properties of the energetic material nitromethane (CH3NO2) for the first 100 picoseconds behind the detonation shock front in a molecular dynamics simulation. We compute optical spectra using the Kubo-Greenwood approach with DFT Kohn-Sham electronic states and compare with spectra computed by linear-response time-dependent density functional theory (TDDFT). The latter typically yields more accurate spectra for molecular systems. At optical wavelengths, the TDDFT method offers a correction of up to 25% in the real part of conductivity relative to the Kubo-Greenwood calculation. We also study the effects of thermal electronic excitations on the calculated spectra, and find no discernible change at optical wavelengths. In all of our calculations, we observe a non-monotonic change over time in the entire spectrum of optical properties as decomposition products evolve. The most optically relevant decomposition products are found to be NO, CNO, CNOH, water, and larger transient molecules. In particular, the disappearance of transient NO and CNO molecules (about 90 picoseconds behind the shock front) is coincident with a substantial decrease in conductivity across the optical spectrum.

Metal CMP applications necessitate the formation of a protective oxide film in the presence of surface active agents, oxidizers, pH regulators and other chemicals to achieve global planarization. Formation and mechanical properties of the chemically modified metal oxide thin films in CMP determine the stresses develop at the interfaces delineating the stability and protective nature of the chemically altered films on the surface of the metal wafer. The balance between the stresses built in the film structure versus the mechanical actions provided during the process can be used to optimize the process variables and furthermore help define new planarization techniques for the next generation microelectronic device manufacturing. In this study, the preliminary studies were concentrated on the very well established tungsten CMP applications and furthermore, titanium CMP applications were presented as a part of surface nano-structuring methodology for biomedical applications by stressing the synergistic effect of protective metal oxide film of titanium in this advanced application.

The electrode materials for VRFB should possess higher electric conductivity, corrosion resistance and hydrophilic properties in sulfuric acid. The characteristics of the electrode materials affect the stability and the energy efficiency of VRFB. Carbon materials are the best suited for VRFB applications. In this study, the calcined treatment, acid treatment and ozone treatment were used to modify the surface of carbon papers. The redox reaction of [VO]2+/[VO2]+ on the modified carbon papers was evaluated by cyclic voltammetry (CV). The surface compositions of carbon materials were analyzed by X-ray photoelectron spectrometry (XPS). The experimental results reveal that three oxidative methods enhance the redox reaction of [VO]2+/[VO2]+. The calcined treatments and acid treatments also enhanced hydrolysis reaction. The mole ratio of O/C apparently increased, but the binding energy of C1s and O1s were not chemically shifted in the acid treatment. The intensity of binding energy of O1s, between 532 eV and 534 eV, apparently increased in the ozone and calcined treatments. The Ox treated samples were more hydrophilic than the Oz treated samples. In the Ox treated samples, the decrease of Rct value indicates that was contributed from the redox reaction of [VO]2+/[VO2]+ and hydrolysis reaction. It does not completely benefit the energy efficiency of VRFB. The 5 x 5 cm2 modified carbon papers were used as electrode materials in the VRFB. The voltage efficiency, coulomb efficiency and energy efficiency reached 93 %, 90 % and 83 %, respectively, at a current density of 12 mA．cm-2 at 0.8-1.8 V.

Small scale explosively driven fragmentation experiments have been performed on Aluminum (Al)-Tungsten (W) granular composite rings processed using cold isostatic compression of Al and W powders with a particle size of 4-30 microns. Fragments collected from the experiments had a maximum size of the order of a few hundred micrometers. This is a dramatic reduction in the fragment size when compared to the 1-10 mm typical for a homogeneous material such as solid aluminum under similar loading conditions. Numerical simulations of the experiment were performed to elucidate the mechanisms of fragmentation that were responsible for this shift in fragmentation size scales. Simulations were performed with a significantly stronger explosive driver to examine how the mechanisms of fragmentation change when the detonation pressure increases.

Bacterial photosynthetic reaction centers (RCs) are promising materials for solar energy harvesting, due to their high internal quantum efficiency. However, applications of RCs in bio-photovoltaic devices so far show relatively low external power conversion efficiency, mainly due to low efficiency of the charge transfer to the electrode. Preferential orientation of RCs on an electrode’s surface can enhance the charge transfer rate to some extent. Yet, the results of direct coupling of RCs to an Au electrode, through cysteine residues from the H-subunit, revealed that direct electron transfer is not efficient. This work focuses on a different approach to achieve high charge transfer rate between an Au electrode and RC protein complexes by employing cytochrome c (Cyt c)\carboxylic acid-terminated linker molecules. This approach preferentially orients RCs with the primary donor site to the electrode. Furthermore, Cyt c can be considered as a conductive linker, while the charge transfer mechanism through carboxylic acid-terminated linker molecules is dominated by tunneling. The photochronoamperometric results for a two electrode cell setup indicated a 156 nA.cm-2 cathodic photocurrent density; the photocurrent was measured in an electrochemical cell with ubiquinone-10 (Q2) in the electrolyte. Negligible photocurrents were observed in the case of coupled RCs to the Au via cysteine residues on H-subunit, with only Cyt c in the electrolyte. These findings contribute to the design of highly efficient bio-photovoltaic devices.

Mg2Si bulk was fabricated by spark plasma sintering (SPS) nano-powder, and the thermoelectric characteristics of the bulk sample were evaluated at temperatures up to 873 K. A pre-synthesized all-molten commercial polycrystalline Mg2Si source (un-doped n-type semiconductor) was pulverized into powder of 75 μm or less. To obtain nano-sized fine powder, the powder was milled using planetary ball mill equipment under an inert atmosphere. Fine Mg2Si nano-powder with a mean grain size of about 500 nm was obtained. XRD analysis confirmed that no MgO existed in the nano-powder. The fine powder was put in a graphite die to obtain a sintering body of Mg2Si and treated by SPS under vacuum conditions. The resulting Mg2Si bulk had high density and did not crack. However, the XRD analysis revealed a small amount of MgO in it. The thermoelectric properties (electrical conductivity, Seebeck coefficient, and thermal conductivity) were measured from room temperature to 873 K. The microstructure of the sintered body was observed by scanning electron microscopy. The maximum dimensionless figure of merit of a sample made from Mg2Si nano-powder was ZT = 0.67 at 873 K.

Under the FP7 HELIOS project a 16 channel 10G transceiver based on a separate integrated transmitter incorporating hybrid lasers and modulators on silicon and a separate receiver both for 1550nm wavelength range has been demonstrated. An MZM (ITLMZ) chip consisting of a single mode hybrid III-V/silicon laser, a silicon Mach-Zehnder (MZ) modulator and an optical output coupler exhibited 10G operation with high BER. A 200GHz 16 channel receiver with polarization management was obtained with a 2D grating coupler, 2xAWGs and 16 Ge photodiodes. Polarization Dispersion Loss (PDL) was below 1dB, Bandwidth (BW) above 20GHz, receiver sensitivity in the order of 0.08 A/W

Hydrothermal nanoparticle synthesis uses high temperature and pressure water to control the chemical processes that lead to specific compositions and structures. Analyses of the chemistry associated with this process have been mainly restricted to bulk thermodynamics in the form of quantities such as solubilities and empirical models based on experimental observations. In this paper we demonstrate for NiO and NiFe2O4 particles how effective reference chemical potentials derived from first principles calculations can be used to predict cluster shapes, nucleation barriers and surface reactivity. Implications for controlling the nanoparticle size and shape by adjusting pH and temperature will be discussed, as well as implications of these results in forming nanostructured materials by cluster condensation.