Results 1 - 10 of 2095
Results 1 - 10 of 2095. Search took: 0.025 seconds
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[en] A significant laser-induced piezooptical response in novel CdCl0.5J 0.5 nanolayers is obtained under the influence of laser illumination. The maximal piezo-optic response is observed for off-diagonal piezooptical tensor components. The layered structure allowed to obtain the thin specimens of thickness up to 1 nm with mirror-like surfaces. The observed studies show huge dependence of the piezooptics on the nanolayer thickness and the photoinduced beam power density. The effect is completely reversible. This fact allows proposing a new type of nanomaterials, which have significant benefits with respect to the other types of piezooptical materials (i.e. a possibility to use them in the laser operated devices). (paper)
[en] The functionalization of fine primary particles by atomic layer deposition (particle ALD) provides for nearly perfect nanothick films to be deposited conformally on both external and internal particle surfaces, including nanoparticle surfaces. Film thickness is easily controlled from several angstroms to nanometers by the number of self-limiting surface reactions that are carried out sequentially. Films can be continuous or semi-continuous. This review starts with a short early history of particle ALD. The discussion includes agitated reactor processing, both atomic and molecular layer deposition (MLD), coating of both inorganic and polymer particles, nanoparticles, and nanotubes. A number of applications are presented, and a path forward, including likely near-term commercial products, is given.
[en] We experimentally demonstrate that metal/oxide/floating-Schottky junction has multiple effective capacitances depending on the amount of electrons stored in the floating metal electrode. The oxide thin film covering the Schottky junction is used to trap electrons in the floating metal. The electron flow into and out of the floating metal is controlled by applying voltage pulses of opposite polarities onto the semiconductor substrate. With the amount of excess charges in the floating metal, the depletion capacitance of Schottky junction varies synchronously, which dominantly affects the effective capacitance of the whole junction. Interestingly, the capacitance of metal/oxide/floating- Schottky junction measured as a function of applied voltage pulse shows a hysteretic behavior, which supports its capacitive memory effect. It is expected that our metal/oxide/floating-Schottky junction can work as a memcapacitor capable of recording multiple switchable capacitance values and it can be readily fabricated with the current Si CMOS technology.
[en] The resonant-type contribution to the infrared absorption enhancement phenomenon was simulated using rigorous coupled wave analysis (RCWA) for well-defined periodic Au arrays. The Au arrays have size parameters compatible with those of vacuum-evaporated thin metal films, which are used conventionally for enhanced infrared absorption spectra measurements. Results obtained using RCWA technique show excellent quantitative agreement with both experimental observations of enhanced infrared absorption of adsorbed species and an electrostatic square column model calculation based on a non-resonant-type electromagnetic mechanism. This fact suggests that the resonant mechanism has a small contribution to the enhanced infrared absorption in an evaporated-film-like structure Au array. (paper)
[en] Full text: Layers of densely tethered polymers (polymer brushes) are of interest due to their unique lubricating, antifouling, and/or biocompatible properties, which stem from their diffuse ‘brushy’ conformation. When these brushes are constructed from stimuli-responsive polymers, their properties can be modulated via a stimulus-induced conformational change, allowing for control of interfacial properties. The brush architecture also affords insight into general polymer behaviour due to the range of powerful techniques that can be used to study planar thin films. Here the interactions between a range of surfactants and a poly(N-isopropylacrylamide) (PNIPAM) brush layer are explored. Using a combination of ellipsometry, Neutron Reflectometry (NR) and quartz crystal microbalance techniques the structure of the layer and the location of the surfactant within the interface are quantified. By subjecting the brush to a confining force and measuring its conformation with NR the mechanical implications of the presence of surfactant are determined. As part of this work, new modelling techniques for the analysis of NR data from diffuse interfaces were developed. A rich surfactant-specific behaviour is observed and found to be headgroup dependent, consistent with prior work on other PNIPAM architectures. Those surfactant species that do interact are found to swell the brush layer, even at concentrations well below the CMC, as micelles decorate the ordinarily neutral PNIPAM with charges. These charges are also found to modify the mechanical properties of the brush, assisting it in resisting confinement. Specific surfactants were found to control brush properties at low concentration (<0.1 wt%); as such this system is a promising multi-responsive interface. (author)
[en] This work presents a study on how threshold voltage (VT) varies with the change in shapes (rectangular and interdigitated finger) and size of the coplanar electrode in electrowetting-on-dielectric (EWOD) device. The EWOD device is fabricated on glass substrate with aluminimum (Al) electrode. Next, synthesized nanocomposite thin film of BST/Teflon® AF is coated on the coplanar electrodes to act as both dielectric and hydrophobic layer. Experiments show that change in electrode dimension (or shape), such as electrode length (L), gap (G) and no. of teeth (T) result in different contact line (CL) between the droplet and the actuated electrode. This leads to change in V T for droplet transport. It is found that higher contact line results in lower threshold voltage, while lower contact line results in higher threshold voltage. This finding matches with the reported theory in literature. (paper)
[en] Temperature-dependent transmission experiments of ZnInSe thin films deposited by thermal evaporation method were performed in the spectral range of 550–950 nm and in temperature range of 10–300 K. Transmission spectra shifted towards higher wavelengths (lower energies) with increasing temperature. Transmission data were analyzed using Tauc relation and derivative spectroscopy. Analysis with Tauc relation was resulted in three different energy levels for the room temperature band gap values of material as 1.594, 1.735 and 1.830 eV. The spectrum of first wavelength derivative of transmittance exhibited two maxima positions at 1.632 and 1.814 eV and one minima around 1.741 eV. The determined energies from both methods were in good agreement with each other. The presence of three band gap energy levels were associated to valence band splitting due to crystal-field and spin–orbit splitting. Temperature dependence of the band gap energies were also analyzed using Varshni relation and gap energy value at absolute zero and the rate of change of gap energy with temperature were determined.
[en] Ionic fluxes have been produced from laser plasma. We can control ionic fluxes density using a different of the laser radiation intensity and ions energy using electric field. It allows to producing using at various regimes of the interaction of an ionic flux with a substrate: etching, creation of a pseudo-diffusive layer and deposition of films with various speed. All these processes can be carried out consistently without depressurization of the vacuum chamber. Such regimes will allow producing sterile high-adhesive coverings. (authors)
[en] The paper presents the results of a study of the effect of the difference in the applied potentials on the structural properties and phase composition of thin CdSe films obtained by the method of electrochemical synthesis. It has been established that a change in the difference of the applied potentials leads to a change in the morphology of the thin films obtained, as well as a reorganization of the phase composition, which can later be used in the practical application of these films. (authors)
[en] We analyze the error associated with the optical transition matrix element spectral dependencies for hydrogenated amorphous silicon and crystalline silicon found by Jackson et al. (Phys Rev B 31:5187–5198, 1985). We find that this error is considerable for photon energies less than 1.5 eV. This suggests that spectral dependencies for the optical transition matrix element, other than those proposed by Jackson et al., are possible for photon energies less than 1.5 eV. With this limitation in mind, we then fit a Lorentzian peak to the crystalline silicon experimental optical transition matrix element result of Jackson et al. Within the framework of the damped harmonic oscillator perspective, plotting the term related to the location of the resonant frequency as a function of the damping coefficient, for a number of thin-film silicon experimental results, we have found a relationship between these model parameters. We suspect that this dependence has important implications for the optical response of various forms of thin-film silicon and related materials.