Numerical analysis and comparison of three metal-oxide-type super-resolution near field structures

Based on the Fresnel-Kirchkoff diffraction theory, we build up a Gaussian diffraction model of metal-oxide-type super-resolution near field structure (super-RENS), which can describe far field optical properties. The spectral contrast induced by refractive index and the structural changes in AgOx, PtOx and PdOx thin films, which are the key functional layers in super-RENS, are studied by using this model. Comparison results indicate that the spectral contrast intensively on laser-induced distribution and change of the refractive index in the metal-oxide films. The readout mechanism of the metal-oxide-type super-RENS optical disc is further clarified. This Gaussian diffraction model can be used as a simple and effective method for choosing proper active materials in super-RENS.

Investigation of the effect of fluoride ions introduction on structural, OH- content and up-conversion luminescence properties in Er3+-doped heavy metal oxide glasses

Effect of fluoride ions introduction on structural, OH- content and up-conversion luminescence properties in Er3+-doped heavy metal oxide glasses have been investigated. Structure was investigated, indicating that fluoride has an important influence on the phonon density, maximum phonon energy of host glasses. With increasing fluoride content, the up-conversion luminescence intensity and quantum efficiencies increase notably, which could not be explained only by the maximum phonon energy change of host glasses. Our results show that, with the introduction of PbF2, the decrease of phonon density and OH- content contributes more to the enhanced up-conversion emissions than that of maximum phonon energy. (c) 2005 Elsevier B.V. All rights reserved.

Structural and up-conversion luminescence properties in Tm (3+)/Yb3+-codoped heavy metal oxide-halide glasses

Tm3+/Yb3+-codoped heavy metal oxide-halide glasses have been synthesized by conventional melting and quenching method. Structural properties were obtained based on the Raman spectra, indicating that halide ion has an important influence on the phonon density and maximum phonon energy of host glasses. Intense blue and weak red emissions centered at 477 and 650 nm, corresponding to the transitions (1)G(4) -> H-3(6) and (1)G(4) -> H-3(4), respectively, were observed at room temperature. The possible up-conversion mechanisms are discussed and estimated. With increasing halide content, the up-conversion luminescence intensity and blue luminescence lifetimes of Tm3+ ion increase notably. Our results show that with the substitution of halide ion for oxygen ion, the decrease of phonon density and maximum phonon energy of host glasses both contribute to the enhanced up-conversion emissions. (c) 2005 Elsevier B.V. All rights reserved.

Effects of techniques of implanting nitrogen into buried oxide on the characteristics of partially depleted SOIPMOSFET

Effects of techniques of implanting nitrogen into buried oxide on the characteristics of the partially depleted silicon-on-insulator (SOI) p-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) have been studied with three different nitrogen implantation doses, 8 x 10(15), 2 x 10(16), and 1 x 10(17) cm(-2). The experimental results show that this technology can affect the threshold voltage, channel hole mobility and output characteristics of the partially depleted SOI PMOSFETs fabricated with the given material and process. For each type of the partially depleted SOI PMOSFET with nitrided buried oxide, the absolute value of the average threshold voltage increases due to the nitrogen implantation. At the same time, the average channel hole mobility decreases because of the nitrogen implantation. In particular, with the high nitrogen implantation doses, the output characteristic curves of the tested transistors present a distinct kink effect, which normally exists in the characteristic output curves of only partially depleted SOI NMOSFETs.

First principles based predictions of the toughness of a metal/oxide interface

We describe a first-principles-based strategy to predict the macroscopic toughness of a gamma-Ni(Al)/alpha-Al2O3 interface. Density functional theory calculations are used to ascertain energy changes upon displacing the two materials adjacent to the interface, with relaxation conducted over all atoms located within adjoining rows. Traction/displacernent curves are obtained from derivatives of the energy. Calculations are performed in mode I (opening), mode II (shear) and at a phase angle of 45 degrees. The shear calculations are conducted for displacements along < 110 > and < 112 > of the Ni lattice. A generalized interface potential function is used to characterize the results. Initial fitting to both the shear and normal stress results is required to calibrate the unknowns. Thereafter, consistency is established by using the potential to predict other traction quantities. The potential is incorporated as a traction/displacement function within a cohesive zone model and used to predict the steady-state toughness of the interface. For this purpose, the plasticity of the Ni alloy must be known, including the plasticity length scale. Measurements obtained for a gamma-Ni superalloy are used and the toughness predicted over the full range of mode mixity. Additional results for a range of alloys are used to demonstrate the influences of yield strength and length scale.

First principles based predictions of the toughness of a metal/oxide interface

We describe a first-principles-based strategy to predict the macroscopic toughness of a gamma-Ni(Al)/alpha-Al2O3 interface. Density functional theory calculations are used to ascertain energy changes upon displacing the two materials adjacent to the interface, with relaxation conducted over all atoms located within adjoining rows. Traction/displacernent curves are obtained from derivatives of the energy. Calculations are performed in mode I (opening), mode II (shear) and at a phase angle of 45 degrees. The shear calculations are conducted for displacements along < 110 > and < 112 > of the Ni lattice. A generalized interface potential function is used to characterize the results. Initial fitting to both the shear and normal stress results is required to calibrate the unknowns. Thereafter, consistency is established by using the potential to predict other traction quantities. The potential is incorporated as a traction/displacement function within a cohesive zone model and used to predict the steady-state toughness of the interface. For this purpose, the plasticity of the Ni alloy must be known, including the plasticity length scale. Measurements obtained for a gamma-Ni superalloy are used and the toughness predicted over the full range of mode mixity. Additional results for a range of alloys are used to demonstrate the influences of yield strength and length scale.

Electrical properties in vanadyl-phthalocyanine-based metal-insulator-semiconductor devices

We investigated electrical properties of vanadyl phthalocyanine (VOPc) metal-insulator-semiconductor (MIS) devices by the measurement of capacitance and conductance, which were fabricated on ordered para-sexiphenyl (p-6P) layer by weak epitaxy growth method. The VOPc/p-6P MIS diodes showed a negligible hysteresis effect at a gate voltage of +/- 20 V and small hysteresis effect at a gate voltage of +/- 40 V due to the low interface trap state density of about 1x10(10) eV(-1) cm(-2). Furthermore, a high transition frequency of about 10 kHz was also observed under their accumulation mode. The results indicated that VOPc was a promising material and was suitable to be applied in active matrix liquid crystal displays and organic logic circuits.

Improved performances of organic light-emitting diodes with metal oxide as anode buffer

We demonstrate extremely stable and highly efficient organic light-emitting diodes (OLEDs) based on molybdenum oxide (MoO3) as a buffer layer on indium tin oxide (ITO). The significant features of MoO3 as a buffer layer are that the OLEDs show low operational voltage, high electroluminescence (EL) efficiency and good stability in a wide range of MoO3 thickness. A green OLED with structure of ITO/MoO3/N,N-'-di(naphthalene-1-yl)-N,N-'-diphenyl-benzidene (NPB)/NPB: tris(8-hydroxyquinoline) aluminum (Alq(3)):10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)-benzopyropyrano(6,7-8-i,j)quinolizin-11-one (C545T)/Alq(3)/LiF/Al shows a long lifetime of over 50 000 h at 100 cd/m(2) initial luminance, and the power efficiency reaches 15 lm/W. The turn-on voltage is 2.4 V, and the operational voltage at 1000 cd/m(2) luminance is only 6.9 V. The significant enhancement of the EL performance is attributed to the improvement of hole injection and interface stability at anode.

Ambipolar organic field-effect transistors with air stability, high mobility, and balanced transport

Ambipolar organic field-effect transistors (OFETs) based on the organic heterojunction of copper-hexadecafluoro-phthalocyanine (F16CuPc) and 2,5-bis(4-biphenylyl) bithiophene (BP2T) were fabricated. The ambipolar OFETs eliminated the injection barrier for the electrons and holes though symmetrical Au source and drain electrodes were used, and exhibited air stability and balanced ambipolar transport behavior. High field-effect mobilities of 0.04 cm(2)/V s for the holes and 0.036 cm(2)/V s for the electrons were obtained. The capacitance-voltage characteristic of metal-oxide-semiconductor (MOS) diode confirmed that electrons and holes are transported at F16CuPc and BP2T layers, respectively. On this ground, complementary MOS-like inverters comprising two identical ambipolar OFETs were constructed.

ENHANCED AMPEROMETRIC DETECTOR FOR LOCAL-ANESTHETICS IN LIQUID-CHROMATOGRAPHY WITH METAL-OXIDE DISPERSED GLASSY-CARBON ELECTRODES

Chemically modified electrodes (CMEs) prepared by the dispersion of metal oxide particles on a glassy carbon (GC) substrate greatly enhance the voltammetric response and amperometric detection of local anesthetics following liquid chromatography (LC). The enhancement is more pronounced with the GC electrodes dispersed by the metal oxides of higher oxidation states (+3, +4) and for the species exhibiting relatively slow electrode kinetics under given conditions. With an applied potential of 1.2 V (vs. SCE), LC amperometric detection of the analytes at the alpha-alumina modified GC surface gives detection limits 2-5 times lower than those obtained at the bare electrode. The metal oxide-dispersed electrodes display significant improvement in sensitivity, and selectivity and indicate excellent preparation reproducibility and performance stability.

Partial oxidation of ethane to syngas over nickel-based catalysts modified by alkali metal oxide and rare earth metal oxide

The catalytic activity, thermal stability and carbon deposition of various modified NiO/gamma-Al2O3 and unmodified NiO/gamma-Al2O3 catalysts were investigated with a flow reactor, XRD, TG and UVRRS analysis. The activity and selectivity of the NiO/gamma-Al2O3 catalyst showed little difference from those of the modified nickel-based catalysts. However, modification with alkali metal oxide (Li, Na, K) and rare earth metal oxide (La, Ce, Y, Sm) can improve the thermal stability of the NiO/gamma-Al2O3 and enhance its ability to suppress carbon deposition during the partial oxidation of ethane (POE). The carbon deposition contains graphite-like species that were detected by UVRRS. The nickel-based catalysts modified by alkali metal oxide and rare earth metal oxide have excellent catalytic activities (C2H6 conversion of similar to 100%, CO selectivity of similar to 94%, 7x 10(4) l/(kg h), 1123 K), good thermal stability and carbon-deposition resistance.