Narrow Results

Pure and Al doped nanocrystalline ZnO films have been prepared on Hydrogen terminated Si(100) substrates by nebulized spray pyrolysis. The dependence of the structural, compositional and electrical properties were investigated using XRD, EDX, AFM and spectrophotometer. The X-ray diffraction data coincide well with the pattern of ZnO reported with the Standard Database. Films annealed at higher temperatures show better orientation, as revealed from X-ray diffraction patterns. Annealing the films in air improved the electrical properties. From the I-V characteristics, the nonlinear coefficient α value has been estimated. Reflectance measurements show good reflectance in the IR region for pure ZnO films, and Al doping improved the reflectance values.

Phase transformations of SiC crystals with grown original defects and thin films have been presented. The SiC crystals were grown by the Tairov method and the films were obtained by the “sandwich” and Chemical Vapor Deposition (CVD) methods.

The analysis of absorption spectra, excitation spectra and low-temperature photoluminescence spectra testifies to the formation of a new microphase during the growth. The complex spectrum can be decomposed into similar structure-constituting spectra shifted on the energy scale relative to the former. Such spectra are indicators of the formation of new nanophases.

The joint consideration of photoluminescence spectra, excitement photoluminescence spectra and absorption spectra testifies to the uniformity of different spectra and the autonomy of each of them. Structurally, the total complexity spectra correlate with the degree of disorder (imperfection) of the crystal and are related to the peculiarities of a defective performance such as a one-dimensional disorder. Three different types of spectra have three different principles of construction and behavior.

Calculations are presented for the dispersion relations of nonlinear plasmon–polariton modes in a layered dielectric structure consisting of a film bounded on each side by another medium. At least one of the media is a metal or semiconductor (such as InSb) with a real, isotropic, frequency-dependent dielectric function, characteristic of an electron plasma. In addition, both media may have a Kerr-type nonlinearity in their dielectric functions. Hence the resulting plasmon–polaritons, which we study in s polarization, are nonlinear and are found to occur in multiple branches. The theory is illustrated by numerical solutions of the dispersion relations for several geometries and physical parameters, and a comparison is made with previous plasmon–polariton results for linear dielectric media as a special case.

A modified surface layer of hydroxyapatite (HA) target was observed before and after pulsed laser deposition. Two types of HA targets were used for laser ablation. We observed that the surface morphology of the target has a very fine compacted grain structure and presents many irregularities with some microroughness and microporosity before laser ablation. The laser ablated regions can be divided into two areas: one area is porous and rough but the other is dense and smooth. The percentage of particles in the films was high for the films produced with targets that were sintered at 1200°C.

The polyacrylamide surface grafted poly(vinyl chloride) (PAM-PVC) film was successfully prepared via a facile copper-mediated surface-initiated atom transfer radical polymerization (SI-ATRP) of acrylamide (AM) from the surfaces of the PVC thin film with their surface labile chlorines as initiation sites. Graft reaction was first-order kinetic with respect to the polymerizing time in the low monomer conversion stage, this being typical for ATRP. A percentage of grafting (PG) of 32.1% was achieved in 6 h, calculated from the elemental analysis results. The surface morphology of the product was characterized with scanning electron microscopy (SEM). The sorption property of the grafted film toward Hg(II) ion was also preliminarily investigated.

Surface photovoltage of semiconductors depend strongly on their electronic structures, in particular, their Fermi energy level. This offers a possibility to characterize photoelectronic behavior using the Kelvin probe structure by measurements of work function (WF). In this paper, ZnO films were prepared using the CVD method and their microstructures and morphology were characterized using the XRD and SEM. Furthermore, photovoltage evolution and WF of selected ZnO samples were measured using a scanning Kelvin probe (SKP) system. It is found that the surface photovoltage and its time-resolved evolution process as well as the energy level structure of ZnO films can be correlated to WF very well. The present study therefore provides a simple and practical methodology for the characterization of photovoltaic behavior of semiconductor films.

Molybdenum thin films were sputter deposited under different conditions of DC power and chamber pressure. The structure and topography of the films were investigated using AFM, SEM and XRD techniques. Van der Pauw method and tape test were employed to determine electrical resistivity and interfacial strength to the substrate, respectively. All the films are of sub-micron thickness with maximum growth rate of 78 nm/min and crystallite size in the range of 4 to 21 nm. The films produced at high power and low pressure exhibit compressive residual strains, low electrical resistivity and poor adhesion to the glass substrate, whereas the converse is true for films produced at high pressure.

Non-cyanide alkaline bath was used to prepare copper thin films. Influences of various temperatures on deposition rates, surface morphologies and microstructures of films were investigated. Copper thin films prepared from non-cyanide alkaline bath show typical nodular structures. Copper films fabricated at higher temperature possess rough surface due to hydrolysis of complexing agents. According to the XRD patterns, all deposited films were crystalline and showed Cu (111), Cu (200) and Cu (220) peaks. The intensity of peak (200) increases gradually with the rise on bath temperatures. Films with maximum thickness (7.5 μm) could be obtained at the temperature of 40°C. From the cyclic voltammetry curve, it was found that the cathodic polarization decreased slightly with increase of bath temperatures. In addition, when the bath temperature was equal to 50°C, current efficiency could reach to 96.95%.

In this work, calcium (Ca)-modified titanium dioxide (TiO₂) nanoparticulate (NP) films were successfully prepared using sparking off Ca-electroplated Ti tips. Aqueous solution of calcium carbonate (CaCO₃) was used as electrolyte in the electroplating process. The experiment was carried out using electric current of 0.02mA applied to titanium electrodes for 10min. The NP films with small and uniform size were deposited on quartz substrate using the sparking process with a high DC voltage of 4kV in ambient air. The as-deposited NP films were then annealed at 800^∘C, 900^∘C and 1000^∘C for 3h under atmospheric pressure to improve their crystallinity. Morphology, structural and optical properties of the NP films were characterized by SEM, XRD, Raman, XPS and UV-Vis spectroscopy. The effects of annealing temperature on the properties of the as-deposited and annealed NP films were reported. Furthermore, photocatalytic activity against 10 $\mu$M of methylene blue (MB) under visible light region will be discussed.

Amplified detection of nucleic acid by G-quadruplex based hybridization chain reaction.

Dow opens Photovoltaics Films Application Lab in Shanghai.

Researchers discover molecular mechanisms of left-right asymmetric control in the sea urchin.

China mulls new rule on human genetic research.

China to phase out organ donation from executed criminals.

Charles River Laboratories to expand research models business in China.

Chinese Science Academy Chief urges seizing on new technological revolution.

BGI contributes genome sequencing and bioinformatics expertise.

Taiwan government to encourage formation of smaller biotech funds.

Crosslinked film of hyperbranched poly(amine-ester) (HPAE) was prepared by crosslinking its terminal hydroxyl groups with glutaraldehyde (GA). Atom force microscope (AFM) and scanning electron microscope (SEM) reveals that they have smooth surfaces, dense and homogenous matrices. It was found that the water static contact angle is smaller than 41.7°, the tensile strength is higher than 8.9 MPa, the elongation at break is higher than 5.1%, the swelling degree is higher than 42% in water, and the Bovine hemoglobin (Hb) adsorption is relatively low. These results indicate that the crosslinked HPAE films might have some potential applications in many areas.

The interaction of different amino acids and vacuum evaporated tetraphenyl porphyrin films was investigated by using kinetic isotherms, UV-vis spectroscopy, quartz crystal microbalance and density functional theory techniques. The adsorption process was analyzed by using pseudo-first-order and pseudo-second-order models. From these results, the adsorption order changed depending on the chemical characteristics of the porphyrin film, although most of the interactions were classified as pseudo-second-order at the films interface. From absorbance measurements, red shifts on the Soret peak positions were observed for all amino acids interacting with the metal free and the ZnTPP systems, while the position of the Soret peak barely change for the CuTPP surface, except for a slight bathocromic shift for arginine. On the other hand, the broadening of the Soret peak was more important for the ZnTPP and H₂TPP surfaces, but the interaction with the CuTPP interfaces decreased the width of the peaks in all cases. In addition, a quartz crystal microbalance analysis was employed to investigate the film sensing performance during amino acid exposure. From these results, positively charged amino acids were more easily adsorbed on the films in contrast with the polar (serine) molecule. DFT calculations exhibited important deformations for H₂TPP, the out-of-plane displacement of the Zn atom for ZnTPP, and hydrogen bond interactions with the CuTPP molecule. DFT also showed high binding energies for the positively charged amino acids but low binding energies for serine in agreement with experimental data. From these results, porphyrin films could be used as selective detectors for various L-amino acid molecules.

Antimony sulfide (Sb₂S₃) films on indium-doped tin oxide (ITO) glass substrates are easily synthesized by a solvothermal method from Sb ultrathin films and S powder as antimony and sulfur source, respectively. The crystalline Sb₂S₃ films were characterized using X-ray powder diffraction (XRD) and Raman spectroscopy. The Sb₂S₃ films are composed of micro-flakes of Sb₂S₃. The composite of Sb₂S₃ film and ITO substrate were used to fabricate the solar cell device (ITO/Sb₂S₃:P3HT/Au), and I–V measurement of the device was performed. Under the optimized condition, the solar conversion efficiency is 0.0026% at 1 sun illumination.

A series of nanocrystalline film materials Ni${}_{1--}$${}_x$Zn${}_x$Fe₂O₄ ($x$ = 0.0, 0.1, 0.3, 0.5) are first synthesized by solid-phase pyrolysis. The results of the X-ray diffraction pattern show that the obtained films consist of nanocrystallites with an average size of 18–21 nm. The sizes of nanocrystals increase with increasing zinc content. The temperature dependence of the resistance becomes pronounced for films with a high concentration of zinc (Ni${}_{0.7}$Zn${}_{0.3}$Fe₂O₄ and Ni${}_{0.5}$Zn${}_{0.5}$Fe₂O₄).

Films of the Mn-based tetragonal Heusler-like alloys, such as Mn–Ga, exhibit a large perpendicular magnetic anisotropy (PMA), small damping constant, small saturation magnetization and large spin polarizations. These properties are attractive for the application to the next generation high density spin-transfer-torque (STT) magnetic random access memory (STT-MRAM). We reviewed the structure, magnetic properties and Gilbert damping of the alloy films with large PMA, and the current status of research on tunnel magnetoresistance (TMR) in perpendicular magnetic tunnel junctions (p-MTJs) based on Mn-based tetragonal Heusler-like alloy electrode, and also discuss the issues for the application of those to STT-MRAM.