Thermal stability of ZnO thin film prepared by RF-magnetron sputtering evaluated by thermal desorption spectroscopy

Thermal stability of sputter deposited ZnO thin films was evaluated by thermal desorption spectroscopy (TDS). Desorption of Zn was mainly observed from the films deposited at low O₂/Ar gas ratio and low RF power. In contrast, O₂ desorption was mainly observed from the films deposited at high O₂/Ar gas ratio and high RF power. The amount of desorbed O₂ from the film increased with increasing the O₂/Ar gas flow ratio and the RF power. Furthermore, the desorption temperature of O₂ increased with increasing the RF power during the deposition. Thermal stability of the ZnO films was controlled not only by the O₂/Ar gas flow ratio, but also applied RF power to the target.     

Characterization of Si-added aluminum oxide (AlSiO) films for power devices

Synthesis of Si-added aluminum oxide (AlSiO) films is attempted as an insulating film with both a wide bandgap and a high dielectric constant. Electrical characteristics of AlSiO films are investigated. Leakage current of the AlO film is suppressed by Si addition and is minimized with Si composition ratio of 12%. Capacitance versus voltage (C-V) measurements are carried out for Au/AlSiO/Si MIS structure. Both flat band shift and hysteresis of the C-V characteristics are suppressed by Si addition. A low leakage current is demonstrated for Au/AlSiO/n-SiC MIS structure.     

Low temperature fabrication of 5-10 nm SiO2/Si structure using advanced nitric acid oxidation of silicon (NAOS) method

We have developed the advanced nitric acid oxidation of Si (NAOS) method to form relatively thick (5-10 nm) SiO₂/Si structure with good electrical characteristics. This method simply involves immersion of Si in 68 wt% nitric acid aqueous solutions at 120 °C with polysilazane films. Fourier transform infrared absorption (FT-IR) measurements show that the atomic density of the NAOS SiO₂ layer is considerably high even without post-oxidation anneal (POA), i.e., 2.28 × 10²² atoms/cm², and it increases by POA at 400 °C in wet-oxygen (2.32 × 10²² atoms/cm²) or dry-oxygen (2.30 × 10²² atoms/cm²). The leakage current density is considerably low (e.g., 10⁻⁵ A/cm² at 8 MV/cm) and it is greatly decreased (10⁻⁸ A/cm² at 8 MV/cm) by POA at 400 °C in wet-oxygen. POA in wet-oxygen increases the atomic density of the SiO₂ layer, and decreases the density of oxide fixed positive charges.     

Effect of particle size and shape on nonresonant random laser action of dye-doped polymer random media

We present an experimental study of the light emission from dye-doped polymer random media dispersed with TiO₂ particles of various sizes, shapes, and structures. Random lasing with nonresonant feedback, similar to that for spherically shaped particles that are used for conventional random lasers, is observed for almost all types of particles and aggregates. The efficiency of random lasing for each medium is analyzed using the relationship between the emission spectrum and the transport mean free path (TMFP), which is measured by enhanced backscattering experiments. Results show that the peak emission intensity depends strongly on the particle shape and structure, whereas the spectral linewidth is governed by the TMFP.     

Recoil-limited laser cooling of 87Sr atoms near the Fermi temperature

A dynamic magneto-optical trap, which relies on the rapid randomization of population in Zeeman substates, has been demonstrated for fermionic strontium atoms on the 1S0-3P1 intercombination transition. The obtained sample, 1x10(6) atoms at a temperature of 2 microK in the trap, was further Doppler cooled and polarized in a far-off resonant optical lattice to achieve 2 times the Fermi temperature.     

Color Conversion Method for Multiprimary Display Using Matrix Switching

The range of reproducible color, i.e., color gamut, of conventional three-primary display devices is sometimes insufficient for reproducing the natural color of an object through color imaging systems. A multiprimary display is being developed for the purpose of reproducing an expanded color gamut using more than three primary colors. In this paper, a color conversion method is proposed to reproduce the natural color by additive mixture of multiprimary colors. The multiprimary color signal in this conversion method is calculated from the three-dimensional color coordinates CIE-XYZ, considering the dynamic range of each primary color. Divided into some linear elements from the polyhedral color solid of the multiprimary display, the conversion considering the constraint of the dynamic range can be performed by simple calculation without iterative calculation or a huge three-dimensional look up table. A fast computation method with a two-dimensional look-up-table is also presented. Using the proposed method, the result of the color reproduction is experimentally demonstrated by a six-primary projection display.     

Continuous flame oxidation in supercritical water

Abstract

Continuous flames have been observed in Supercritical water oxidation (scWO) of isopropyl alcohol (IPA), using a vertical continuous reactor with sapphire windows and a mixing nozzle. Two types of continuous flame were confirmed: the one was long pale blue colored and the other was red short cone shaped, changing blue to red at around air ratio 2.0. The flame was strongly influenced by IPA concentration, air ratio and design of the mixing nozzle. Results for decomposition of PA are presented for IPA concentrations ranging from 600 up to 28260 ppm as TOC and initial reactor temperatures, were mostly around 490°C, at 25 MPa. Decomposition rate at steady state was over 99.9%. Experimentally measured CO₂ and O₂ concentrations at the flue gas were in good agreement with theoretically calculated values. Even for low air ratio as 1.1, high decomposition rate without CO, NO, NO₂ was achieved.     

Highly Efficient α‐Sialylation by Virtue of Fixed Dipole Effects of N‐Phthalyl Group: Application to Continuous Flow Synthesis of α(2‐3)‐and α(2‐6)‐Neu5Ac‐Gal Motifs by Microreactor

Highly α‐selective sialylation of sialic acid N‐phenyltrifluoroacetimidate with various galactose and lactose acceptors has been achieved by introducing the C‐5 N‐phthalyl group on the donor. The “fixed dipole effect” of the N‐phthalyl group was proposed to explain the high reactivity and α‐selectivity. The microfluidic system was applied to the present α‐sialylation, which is amenable to large‐scale synthesis. The N‐phthalyl group was removed by treatment with methylhydrazine acetate, for which protocol can be readily applied to the synthesis of a variety of sialic acid‐containing oligosaccharides.