Using high-sensitivity confocal time-resolved photoluminescence (PL) techniques, we found an ultrafast PL (40 ps-5 ns) from impurity-free surface flaws on fused silica. This PL is excited by the single-photon absorption of sub-band gap light. Regions which exhibit this PL are strongly absorptive well below the band gap, as evidenced by a propensity to damage with 3.5 eV nanosecond-scale laser pulses. Very high defect densities are needed to explain the damage thresholds observed. For such high defect densities, significant interactions between defects may strongly affect the temporal characteristics of the emission of electronic excitations. We propose that the distribution in lifetimes observed is not simply due to a large variety of defect states, but due to a variety of energy transfer interactions between defect states.

Influence of processing condition on mechanical and structural properties of diamond-like carbon (DLC) by focused ion-beam chemical vapor deposition (FIB-CVD) method was investigated. The DLC specimens were produced under conditions of varying supplied amount of material gas and probe current of FIB. Volume determination results of DLC structures indicated that a deposition rate was increased with both the amount of gas and the probe current. To evaluation of mechanical property, indentation hardness was measured by a nano-indentation tester. From evaluation of mechanical property, it was found that the indentation hardness was sensitive to the processing condition, showing in the range of 8-13 GPa. The hardness of DLC structures was seemed to be lower when etching process higher contributed for formation process. Crystallographic structure of DLC remained amorphous even though the mechanical properties varied widely. Results of hydrogen concentration measurement indicated that increase of hydrogen concentration might lead to decrease of hardness.

This paper presents fabrication details and preliminary experimental results for graphene/p-silicon Schottky-barrier solar cells, where graphene is used as a transparent electrode and forms a rectifying junction with silicon wafer. Deviations from expected Schottky behavior in the form of large diode-ideality factors and s-shaped current-voltage curves observed in measurements are reported and analyzed.

This study describes the fabrication of hybrid micro- and nanostructures of semiconductor nanocrystals arranged in microscopic lines inside of a borosilicate glass doped with CdSxSe1-x. This was performed using a two step process of (1) ultrafast laser modification and (2) heat treatment. The glass was photomodified using focused sub-picosecond infra-red pulses with 1 MHz repetition rate to create linear domains with local compositional variations. Heat treating the sample at temperatures near glass transition preferentially precipitated semiconductor in the modified regions, as evidenced by confocal fluorescence microscopy. The optical properties of the precipitated nanocrystals varied with heat treatment duration.

Indium oxide-doped hematite xIn2O3·(1-x)α-Fe2O3 (x = 0.1-0.7) solid solution systems were synthesized using mechanochemical activation. The microstructures, magnetic and thermal properties of the system were dependent on In2O3 molar concentration x and ball milling time. XRD results showed that the completion of In3+ substitution of Fe3+ in hematite lattice occurs after 12 h ball milling for x = 0.1. For x = 0.3, 0.5 and 0.7, the substitutions between In3+ and Fe3+ into hematite and In2O3 lattices occur simultaneously. The lattice parameters of hematite and In2O3 vary as a function of ball milling time. The change in these parameters was due to ions substitution between In3+and Fe3+ and the decrease in grain sizes. Mössbauer spectra of the system with x = 0.3 were fitted with three sextets and two quadrupole-split doublets after milling, representing In3+ substitution of Fe3+ in hematite lattice and Fe3+ substitution of In3+ in two different sites of In2O3 lattice. TGA results showed that the hematite decomposition is enhanced due to the smaller hematite grain size. The crystallization of hematite and In2O3 was suppressed with the drops of enthalpy values due to the stronger solid-solid interactions after ball milling. These caused gradual In3+-Fe3+ substitution in hematite/In2O3 lattices.

Organic thin film photovoltaic (PV) cells have attracted attention because of their ease of fabrication and potential for low cost production. In this paper, we study the effects of chemical modification of indium-tin-oxide (ITO) on the performance of organic PV cells. The organic PV cells are fabricated, with the cell configuration of ITO/copper phthalocyanine (CuPc) (20 nm)/fullerene (C60) (40 nm)/Al with and without bathocuproine (BCP) (10 nm) between C60 and Al. By the use of para-substituted benzenesulfonyl chlorides with different terminal groups of H- and Cl-, the energy offset at the ITO/CuPc interface is tuned widely depending upon the interface dipoles and thus the correlation between the change in the ITO work function and the performance of the PV cells by chemical modification is examined.

The retention time of the resistive state is a key parameter that characterizes the possible utilization of the RRAM devices as a non – volatile memory device. The understanding of the mechanism of the time relaxation process of the information state may be essential to improve their performances. In this study we examine RRAM devices based on metal / YBCO interfaces in order to comprehend the physics beneath the resistive switching phenomenon.

Our experimental results show that after producing the switching of the resistance from a low to a high state, or vice versa, the resistance evolves to its previous state in a small but noticeable percentage. We have measured long relaxation effects on the resistance state of devices composed by metal (Au, Pt) / ceramic YBCO interfaces in the temperature range 77 K – 300 K. This time relaxation can be described by a stretched exponential law that is characterized by a power exponent n = 0.5, which is temperature independent, and by a relaxation time τ that increases with increasing the temperature. These characteristics point out to a non-thermally assisted diffusion process that could be associated with oxygen (or vacancy) migration and that produces the growth of a conducting (or insulating) fractal structure.

Thin transparent conducting oxide (TCO) films of gallium-doped zinc oxide have been deposited on glass substrates by atomic layer deposition (ALD) using diethyl zinc, triethyl gallium and water vapour as precursors. The gallium-doped zinc oxide films were deposited over the temperature range 100-350°C. Transmission electron microscopy reveals that the as-deposited films are polycrystalline in character. The electrical resistivity of the gallium-doped zinc oxide films was evaluated using four-point probe and contactless measurement methods as a function of film thickness. The lowest sheet resistance of 16 Ω/☐ was measured from a film thickness of 400nm and a gallium content of 5 atomic percent. The electron Hall mobility of this film was 12.3 cm2/Vs. The visible transmittance of the films was 78% with a haze of 0.2%.

Reaction pathway analysis was carried out for homogeneous dislocation nucleation in perfect crystal Mo. The reaction sampling method employed was based on the Nudged Elastic Band algorithm and other extended schemes. Results obtained were compared with corresponding results for Cu and Si. The stress range for activation energies less than 5 eV is found to be considerably higher for Mo than those for Cu as well as Si. Stresses in excess of 12 GPa make homogeneous dislocation nucleation in Mo an unrealistic transition. The results also show the dislocation cores under this stress range to be diffused, with shear displacement of particles being considerably less than the Burgers vector. Depending on the applied stress, displacement of extra slip-plane atoms can be considerable in Mo. This is in contrast to Cu, in which dislocation nucleation is essentially a two-plane phenomenon.

Magneto-optical garnet based optical circulator was designed and fabricated with wafer-scale technology. Modeling and simulation strategy is established for the optimization of a new design of circulator based on ring cavity. Wafer-scale technological process is developed and demonstrated allowing fabrication of the optimized BIG/GGG buried ring circulator.

Cortical and cancellous bones were demineralized and deproteinized using 1 NHCl and 6% NaOCl, respectively. Experiments were performed at 37°C. The rateconstants were calculated and the structural features of untreated andcompletely demineralized and deproteinized samples were studied by scanningelectron microscopy, showing that intact, contiguous structures wereobtained. For both cases, the rate constant was higher for cancellous bonethan the cortical bone.

A personal review is presented. We review the renaissance in thermoelectric materials research that started in 1993 with the introduction of the nanostructure concept as a potential method to both increase the power factor and decrease the thermal conductivity and to even do both at the same time. The earliest work was limited to model systems for the demonstration of proof of principle. More recently the focus has evolved into demonstration of embedding the phenomena into bulk samples based on composites and superlattices. We here review this evolution of the nanothermoelectricity field. The resulting current activity is attracting many new researchers, industrial interest and the emergence of new ideas. We now look to the further development of these new ideas, and to the introduction of more new ideas and new approaches, as the field is now approaching the stage of commercial relevance.

Both luminous efficiency and lifetime in blue fluorescence organic lightemitting devices (OLEDs) have been improved by modified HTMs with higherLUMO energy levels. The LUMO energy levels of HTM were increased bymodifying substituent in HTM molecules. Two HTMs containing ortho and metabiphenyl substituent and one HTM containing thiophene substituent weresynthesized via palladium catalyzed amine coupling reactions to compare witha para biphenyl substituent HTM-1 as a standard molecule. According to TDDFTcalculations, these three modified HTMs showed 0.05-0.15 eV higher LUMOenergy levels compared to the para biphenyl substituent HTM-1. The luminousefficiency and the lifetime (LT90) of OLEDs using HTM-2 at 500 cd/m2 have been enhanced up to 20 % and 52 %, respectively,compared to the standard device using HTM-1.

Copper indium diselenide (CIS) based solar cells are one among the promising thin film solar cells. Most of the processes reported for the preparation of CIS directly or indirectly involve Se vapor or H2Se gases which are extremely toxic to health and environment. In this work, we report the preparation of CIS thin films by stacked layers of Glass/In/Se/Cu2Se and Glass/In/Se/Cu2Se/Se. For this, first indium (In) thin film was thermally evaporated on glass substrate on which selenium (Se) and copper selenide (Cu2Se) thin films were deposited sequentially by chemical bath deposition. Selenium thin films were grown from an aqueous solution containing Na2SeSO3 and CH3COOH at room temperature, triple deposition for 7, 7 and 10 min from consecutive baths. Copper selenide thin films were deposited at 35 °C for 1 hour from an aqueous bath containing CuSO4, Na2SeSO3 and NH4OH. Analysis of the X-ray diffraction patterns of the thin films formed at 400 °C from the precursor layer containing extra selenium layer showed the presence of chalcopyrite CuInSe2, without any secondary phase. Morphology of all the samples was analyzed using Scanning Electron Microscopy. Optical band gap was evaluated from the UV-Visible absorption spectra of these films and the values were 1.1 eV and 1 eV respectively for CIS thin films formed at 400 °C from the selenium deficient and selenium rich precursor layers. Electrical characterizations were done using photocurrent measurements. Thus preparation of a CuInSe2 absorber material by a non-toxic selenization process may open up a low cost technique for the fabrication of CIS based solar cells.

We present a fully automated microwave-based synthesis setup for colloidal nanoparticles. Integrated absorption and photoluminescence online analytics opens the possibility to monitor the growth of various nanoparticles at any stage of the reaction. Spectroscopic investigation within the first seconds of a reaction is accessible opening the possibility to detect potential critical size nuclei as a function of the reaction conditions. Beside the possibility to perform systematic mechanistic studies, this system allows a high degree of synthesis control leading to very good product reproducibility. In conjunction with an automated auto sampler unit systematic multiple reactions can be performed one after each other and compared. The setup is remote-controllable allowing worldwide online control accessibility over the synthesis setup including data processing, visualization and storage. The performance of the setup will be demonstrated by using the synthesis of CdSe nanocrystals as a model system and can be extended to the synthesis of various metallic and semiconducting nanoparticles.

In this paper, the physical metallurgy and properties of a novel family of high-strength γ-TiAl-based alloys is reviewed succinctly. These so-called TNM™ alloys contain Nb and Mo additions in the range of 3 - 7 atomic percent as well as small additions of B and C. For the definition of the alloy composition thermodynamic calculations using the CALPHAD method were conducted. The predicted phase transformation and ordering temperatures were verified by differential scanning calorimetry and in situ high-energy X-ray diffraction. TNM alloys solidify via the β-phase and exhibit an adjustable β-phase volume fraction at temperatures, where hot-working processes are performed. Due to the high volume fraction of β-phase these alloys can be processed isothermally as well as under near conventional conditions. In order to study the occurring deformation and recrystallization processes during hot-working, in situ diffraction experiments were conducted during compression tests at elevated temperatures. With subsequent heat-treatments a significant reduction of the β-phase is achieved. These outstanding features of TNM alloys distinguish them from other TiAl alloys which must exclusively be processed under isothermal conditions and/or which always exhibit a high fraction of β-phase at service temperature. After hot-working and multi-step heat-treatments, these alloys show yield strength levels > 800 MPa at room temperature and also good creep resistance at elevated temperatures.