bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of an In situ Infrared Spectroscopic Measurement of Plasma-Induced Reactions in Ethanol
Authors: Shinohara Masanori , Fuakae Akihiro , Amano Katsuhiro , Yoshida Yuta , Matsuda Yoshinobu , Fujiyama Hiroshi
Published: November 2013

An in situ monitoring system for plasma-induced reactions in ethanol was developed by infrared absorption spectroscopy in multiple internal reflection geometry. We monitored in situ the preferential decrease in the IR peak intensity of CH3and OH groups in liquid ethanol. In addition, we monitored in situ the preferential inclusion of OCH3and free OH groups deposited on a multiple internal reflection prism. Unlike optical emission spectroscopy, the IR-based technique detects non-light-emitting compounds. It presents as a powerful alternative tool for monitoring liquid-phase plasma reactions.
Finite-Difference Time-Domain Simulation on Transmission of Millimeter Waves through Miter Bends
Authors: Kashima Naoya , Nakamura Hiroaki , Takayama Arimichi , Tamura Yuichi , Kubo Shin
Published: November 2013

We have simulated the distribution of electromagnetic (EM) waves through a system composed of miter bends by finite-difference time-domain (FDTD) simulation. To study the effect of mode conversion by miter bends, three shapes of miter bends have been simulated. For the miter bend that has processed grooves inside, the profile of the output EM waves is changed slightly from that of the input wave (HE11mode). As a result, this case exhibits the best shape of the miter bend in our simulation. In the miter bend without processed grooves inside, the output EM waves change more than in the case of the miter bend with grooves, because mode conversion occurs at the surface in miter bends without grooves. In the simple bend, which changes the direction of EM waves gradually, the profile of the output EM waves is deformed and the input profile is not conserved. Comparing the above three cases, we found that the grooves lead to more efficient to conservation of the profile of EM waves.
High H Radical Density Produced by 1-m-Long Atmospheric Pressure Microwave Plasma System
Authors: Itoh Hitoshi , Kubota Yusuke , Kashiwagi Yusaku , Takeda Keigo , Ishikawa Kenji , Kondo Hiroki , Toyoda Hirotaka , Hori Masaru
Published: November 2013

We have developed an atmospheric pressure microwave plasma system with a microwave antenna consisting of two microwave guides, which have a discharge line with 41 slots. The antenna is set against a movable stage with a heater in a process chamber. The process gas used is a 1% H2 gas diluted by Ar gas. We clarified various characteristics, such as gas temperature, electron density, and hydrogen radical density, using this system, and found that the gas temperature is about 1000 K, the electron density is 1×1015 cm-3, and the H radical density is 1×1016 cm-3 at the slot under the condition of a 10 GHz, 1.5 kW, pulsed microwave with a pulsed voltage of 2.5, a pulsed frequency of 4 kHz, and a duty ratio of 0.16.
Generation of Three-Dimensionally Integrated Micro-Solution Plasma and Its Application to Decomposition of Methylene Blue Molecules in Water
Authors: Shirafuji Tatsuru , Himeno Yuta
Published: November 2013

Integrated micro-solution plasma was generated in gas bubbles in porous dielectric materials filled with a gas/liquid mixed medium. Methylene blue aqueous solution (3.8 mg/L, 150 mL) was treated with the integrated micro-solution plasma. The decomposition of methylene blue molecules was confirmed through the reduction in the optical absorption coefficient at 665 nm for methylene blue molecules, and through the fact that the absorption coefficient at 665 nm did not recover even after stirring in air. The decomposition efficiency of the integrated micro-solution plasma was 15.7-fold higher than that of conventional solution plasma.
Single GaN-Based Nanowires for Photodetection and Sensing Applications
Authors: Hertog Martien den , Songmuang Rudeesun , Gonzalez-Posada Fernando , Monroy Eva
Published: November 2013

We present a study of the structural properties of GaN/AlN heterostructured nanowires grown by plasma-assisted molecular-beam epitaxy. We combine transmission electron microscopy measurements with theoretical calculations of the strain distribution and band diagram in order to gain understanding of the potential distribution in these nanostructures. The effects of surface states and of the formation of a core–shell heterostructure are discussed. The structural properties are correlated with the performance of GaN-based nanowire photodetectors and sensors. In particular, we discuss a sensor design where the insertion of an AlN barrier in a GaN nanowire is proposed as a material engineering solution to inhibit the electron transport through the core, confining the current close to the nanowire sidewalls.
InGaN-Based Light-Emitting Diodes Fabricated on Nano Patterned Sapphire Substrates with Pillar Height of More than 600 nm by Nanoimprint Lithography
Authors: Okada Narihito , Egami Takuya , Miyoshi Seita , Inomoto Ryo , Yamane Keisuke , Tadatomo Kazuyuki , Nishimiya Tomoyasu , Hiramoto Michihiro , Motoyama Shin-ichi
Published: November 2013

GaN-based light-emitting diodes (LEDs) were fabricated on nano patterned sapphire substrates (nano-PSSs) by nanoimprint (NIP) lithography. A nano-PSS with a pillar height of more than 600 nm was achieved. The surface emission of the LEDs was strongly affected by pillar height, and the surface emission intensity was highest at a pillar height of 250 nm. In contrast, the external quantum efficiency of the LEDs on the nano-PSSs with diameters of 100 and 450 nm was approximately 30% higher than that on a flat sapphire substrate, which is similar to that on a conventional PSS.
Growth of GaN on Metallic Compound Graphite Substrate Using Hydride Vapor Phase Epitaxy
Authors: Kim Ji Young , Lee Gang Seok , Jung Se-Gyo , Park Min Ah , Shin Min Jeong , Yi Sam Nyung , Yang Min , Ahn Hyung Soo , Yu Young Moon , Kim Suck-Whan , Lee Hyo Suk , Kang Hee Shin , Jeon Hun Soo , Sawaki Nobuhiko
Published: November 2013

In this paper, the GaN poly crystal was grown by hydride vapor phase epitaxy at 1090 °C on the metallic compound graphite substrate with good heat dissipation. The coefficient of thermal expansion of the metallic compound graphite substrate is 6.2 µm/(m·K). The heat conductivity is 150 W/(m·K), and specific gravity is 3.1. The metallic compound graphite substrate was gained higher thermal conductivity more than the sapphire substrate through by injecting the nonferrous metal in the porosity carbon graphite base. The GaN poly crystal grown along the [0001] c-axis by hydride vapor phase epitaxy was observed on the metallic compound graphite substrate through the scanning electron microscope and energy dispersive spectroscopy. And electrical characteristic of substrate with each different condition was investigated by Hall Effect measurement.
Atomic Core Structures Associated to the Threading Dislocation with <11̄00> Burgers Vector and [0001] Line Direction in GaN
Authors: Béré Antoine , Ruterana Pierre , Chauvat Marie-Pierre , Koulidiati Jean
Published: November 2013

The <11̄00 > edge dislocation in GaN has been investigated by means of atomistic computer simulation. It's core structure exhibits three configurations that are related to the location of the origin of displacements imposed to the atoms when generating the dislocation in the initial configuration. They are described by: (a) 8- and 4-coordinated channels (8/4 core); (b) 8-, 5-, and 5-coordinated channels (8/5/5 core); and (c) 9- and 5-coordinated channels (9/5 core). An additional configuration where the <11̄00 > dislocation decomposes in two 8-coordinated channels a= 1/3<12̄10 > dislocations is also generated and it exhibits the lowest energy. This is in agreement with high resolution transmission electron microscopy observations and image simulations carried out on an asymmetric Σ7 [0001] tilt grain boundary in which only cores of elemental a type dislocations have been determined.
Evaluation of a Gate-First Process for AlGaN/GaN Heterostructure Field-Effect Transistors
Authors: Li Liuan , Kishi Akinori , Shiraishi Takayuki , Jiang Ying , Wang Qingpeng , Ao Jin-Ping , Ohno Yasuo
Published: November 2013

In this study, we evaluated the annealing temperature and time-dependent electrical properties of AlGaN/GaN heterostructure field-effect transistors (HFETs) utilizing TiN/W/Au as the gate electrode. With the annealing temperature increasing from 750 to 900 °C for the annealing time of 1 min, the sheet resistance of TiN/W/Au films increased gradually while that of the ohmic contact was minimum (0.66 Ω mm) at 800 °C. From the current–voltage characteristics of the Schottky diode and HFETs, it is demonstrated that annealing at 800 °C showed the lowest on-resistance and highest maximum drain current. By prolonging the annealing from 0.5 to 10 min at 800 °C, good device performance was achieved when the annealing time was 1 and 3 min, while the device performance degraded showing an increased gate leakage current and gate resistance with increasing annealing time. These results demonstrated that the TiN/W/Au gate, which can withstand 800 °C annealing for a short time, is suitable for application in the gate-first process for AlGaN/GaN HFETs.
High-Temperature Isothermal Capacitance Transient Spectroscopy Study on Inductively Coupled Plasma Etching Damage for p-GaN Surfaces
Authors: Aoki Toshichika , Wakayama Hisashi , Kaneda Naoki , Mishima Tomoyoshi , Nomoto Kazuki , Shiojima Kenji
Published: November 2013

The effects of the inductively coupled plasma (ICP) etching damage on the electrical characteristics of low-Mg-doped p-GaN Schottky contacts were evaluated by high-temperature isothermal capacitance transient spectroscopy. A large single peak for an acceptor-type surface state was dominantly detected for as-grown samples. The energy level and state density were obtained to be 1.18 eV above the valence band, which is close to a Ga vacancy (VGa), and 1.5×1013 cm-2, respectively. It was speculated that a small portion of Ga atoms were missing from the surface, and a high VGa density was observed in a few surface layers. The peak intensity decreased by 60% upon annealing at 800 °C, and further decrease was found by ICP etching. This decrease is consistent with the suppression of the memory effect in current–voltage characteristics. Upon annealing and ICP etching, since the VGa structure might be disordered, the peak intensity decreased.
Band-Edge Luminescence Degradation by Low Energy Electron Beam Irradiation in GaN Grown by Metal–Organic Vapor Phase Epitaxy in H2 and N2 Ambients
Authors: Nykänen Henri , Suihkonen Sami , Svensk Olli , Sopanen Markku , Tuomisto Filip
Published: November 2013

The processing and characterization of optical components often requires the use of low energy electron beam (e-beam) techniques, such as scanning electron microscopy or electron beam lithography. The e-beam irradiation has been shown to produce band-edge luminescence degradation in GaN films grown by metal–organic vapor phase epitaxy (MOVPE), down to 20% of the original intensity in both photoluminescnece and cathodoluminescence measurements. The degradation is shown to be strongly related to activation of gallium vacancies in the GaN lattice. In this paper, this effect has been studied with GaN samples grown in two different carrier gases, N2 and H2. The degradation behavior appears almost identical in both cases, implying the vacancy formation to be independent of the carrier gas. Hence, MOVPE GaN electron beam irradiation resistance cannot be improved with the change of the carrier gas.
Magnetite Nanoparticles Synthesized Using Pulsed Plasma in Liquid
Authors: Kelgenbaeva Zhazgul , Omurzak Emil , Takebe Shintaro , Abdullaeva Zhypargul , Sulaimankulova Saadat , Iwamoto Chihiro , Mashimo Tsutomu
Published: November 2013

Iron oxide nanoparticles have attracted much attention over the last few years owing to their fundamental importance and technological applications. In this work, spherical ferromagnetic Fe3O4 nanoparticles with an average diameter of 19 nm were synthesized by a simple and one-step method, pulsed plasma in liquid. Pulsed plasma, induced by a low-voltage spark discharge, was submerged in a dielectric liquid at a voltage of 200 V, a current of 6 A, a frequency of 60 Hz, and a single discharge duration of 10 µs. Water with different concentrations of 1-hexadecylpyridinium bromide (CPyB) was applied as a liquid, and several experiments made evident that the surfactant concentration affects the phase compositions of the produced materials. The purity of the magnetite phase in the sample increased (from 65 to 98%) with increasing CPyB concentration (from 0.10 to 0.84 g) in 200 ml of water. The crystal structure of magnetite (Fe3O4) nanoparticles with the F
d3̄m space group and a lattice parameter of a = 0.8393 nm was evident from X-ray diffraction results. Magnetite nanoparticles were investigated further by high-resolution transmission electron microscopy/energy-dispersive spectroscopy and thermogravimetrical analysis, and using a vibrating sample magnetometer.
New Cu(TiIrNx) Alloy Films for Solder Bump Flip-Chip Application
Authors: Lin Chon-Hsin
Published: November 2013

A new copper alloy that shows fine thermal stability and adhesion to the substrate is developed in this study by cosputtering Cu, Ti, and Ir on a barrierless Si substrate within an Ar/N2 gas atmosphere to form a Cu(TiIrN
x
) film. To reduce manufacture cost, we can replace both the wetting and diffusion layers underneath flip-chip solder joints in conventional under bump metallurgy with this thermally stable film, which exhibits weak, if any, interactions between the film and the substrate after annealing at 700 °C for 1 h. The alloy film's dissolution rate is lower than that of pure Cu by at least one order of magnitude, with a fine solderability similar to that of pure Cu. The film developed in this study seems to be a good candidate material for barrierless Si metallization and/or flip-chip solder bump application, with a low consumption rate comparable to that of Ni.
Property Variation of Ni–W Electroformed Mold for Micro-Press Molding
Authors: Yasui Manabu , Kaneko Satoru , Takahashi Masaharu , Ito Hiroaki , Arai Masahiro , Hirabayashi Yasuo , Ozawa Takeshi , Maeda Ryutaro
Published: November 2013

We proposed a simple method to fabricate a Ni–W electroformed mold for glass micro-press molding. For example, borosilicate glass (D263) was molded using the Ni–W electroformed mold. A Ni–W electroformed mold with a fine line was fabricated by photolithography and electroforming technology. Additionally, the Ni–W electroformed mold did not require a release layer. As the result of molding D263 at 883 K, the minimum pitch of the glass pattern was the same as that of the Ni–W electroformed mold. We argue that the crystallization of amorphous Ni–W occurred with the activation energy derived from the heating of micro-press molding. The heating temperature was 833 K. Additionally, the release characteristics of a Ni–W film were improved by increasing the percentage of W. In terms of the thermochemical stability and high content rate of W, we indicated that Ni–W electroformed molds can be used repeatedly for glass micro-press molding.
Characterization of Resistive Switching Behaviors of RF Sputtered Si Oxide Resistive Random Access Memories with Ti-Based Electrodes
Authors: Ohta Akio , Fukusima Motoki , Makihara Katsunori , Murakami Hideki , Higashi Seiichiro , Miyazaki Seiichi
Published: November 2013

We have fabricated metal–insulator–metal (MIM) diodes with a radio frequency (RF) sputtered Si oxide (SiO
x
) dielectric layer and studied the impact of three kinds of top electrodes (Ti, TiN, and Pt) on the resistive switching characteristics of the MIM diodes by current–voltage (I–V) measurements. For the MIM diodes with Ti-based electrodes, a significant increase in the initial current level and a decrease in the ON/OFF resistance rate were observed as compared to those of the reference MIM diodes with the Pt top electrodes. To gain a better understanding of the changes in the current levels with the top electrodes, the chemical bonding features in the region near the interface between the top electrode and SiO
x
layer were investigated using hard X-ray photoemission spectroscopy (HAXPES) under synchrotron radiation (hν= 7939 eV). From HAXPES analyses, it was found that the SiO
x
surface partially reacted with the Ti and TiN top electrodes during the deposition. Due to the formation of a TiO
x
barrier layer at the interface between the TiN top electrode and SiO
x
layer, distinct bi-polar type resistive switching with lower operation voltages below 2.0 V has been achieved.
Fabrication of Nanostructured ZnO Films for Transparent Field Emission Displays
Authors: Zulkifli Zurita , Munisamy Subramanian , Yusop Mohd Zamri Mohd , Kalita Golap , Tanemura Masaki
Published: November 2013

A highly transparent field emitter was achieved by Ar+ ion irradiation onto highly transparent and conducting ZnO films deposited on glass substrates. The as-deposited flat ZnO films before ion irradiation, which showed 90% transmittance and 186 Ω/□ sheet resistance, showed no field emission current up to 15 V µm-1. The ZnO film ion-irradiated at an ion-incidence angle of 45° showed nanocone structures about 200–400 nm in height and 6–8 µm-2 in number density. Since the nanocone size was less than the wavelength of visible light, the transmittance was maintained at 86% for the ion-irradiated ZnO film. The field emission properties of the ion-irradiated ZnO film revealed that a current density of 1 µA cm-2 was achieved at 6.2 V µm-1, and that the field enhancement factor was calculated to be 2252 from the Fowler–Nordheim plot. Thus, the nanostructured ZnO film is believed to be promising as a transparent field emitter.
Effects of Al and V Additions on Mechanical Response in Thick TiSiCN Nanocomposites Deposited Using Plasma-Enhanced Magnetron Sputtering
Authors: Chan Yu-Chen , Chen Hsien-Wei , Wei Rong-Hua , Lee Jyh-Wei , Duh Jenq-Gong
Published: November 2013

Thick TiSiCN and TiAlVSiCN nanocomposite coatings were fabricated by plasma-enhanced magnetron sputtering (PEMS). Characterizations by electron probe microanalyzer (EPMA) and XRD revealed the dependence of films with various precursor flow rates on the constituent composition and structure evolution in coatings. HRTEM images clearly confirmed that a nanocomposite structure existed with grain size below 10 nm. It was believed that nanocrystalline TiC
x
N1-x
-based phases with B1 structure were embedded in an amorphous SiC
y
N
z
matrix, and such phase segregation ameliorated the hardness and H/E ratios. In the scratch and ball-on-disc wear tests, the evidence from crack initiation resistance, friction coefficient, and worn surfaces verified that thick nanocomposites exhibited remarkable tribological resistance. Hybrid anti-wear mechanisms on the basis of mechanical property variation, composition distribution, and microstructure evolution were proposed to elucidate the favorable durability of these thick films.
Interaction of Microwaves with Synthetic Type A Zeolite Containing Water
Authors: Tanaka Masahiro , Takayama Sadatsugu , Sano Saburo
Published: November 2013

A synthetic honeycomb type A zeolite adsorbent was regenerated through microwave irradiation in a single-mode cavity microwave at 2.46 GHz. The regeneration mechanism was investigated by comparing the heating properties, thermogravimetric properties, and dielectric properties of the synthetic zeolite samples. The hydrated zeolite sample was easily heated to over 200 °C, although a difference in the impedance matching frequency of only 0.01 GHz sharply reduced the maximum heating and increased the regeneration time. The adsorbed water in the hydrated zeolite initially acted as a heating agent by absorbing microwave energy, because the dielectric loss factor of water is higher than that of synthetic zeolite around 2.45 GHz. From 50 to 250 °C, the zeolite itself also absorbed microwave energy.
Optical and Magnetic Properties of Hydrothermally Synthesized Al-Doped ZnO Nanorods
Authors: Lin Teng-Tsai , Young San-Lin , Kung Chung-Yuan , Chen Hone-Zern , Kao Ming-Cheng , Shih Neng-Fu , Shi Jen-Bin , You Jia-He
Published: November 2013

Hereby ZnO and Al-doped ZnO nanorods were fabricated on the silicon substrate by a low temperature hydrothermal process at 90 °C. The nanorods were prepared to study the Al doping effect on their structural, optical and magnetic properties. The Al-doped nanorods exhibited a c-axis (002) oriented wurtzite hexagonal structure as that of ZnO nanorods. Then, photoluminescence spectra showed an increase of visible emission peak intensity indicating the increase of defects in the nanorods. The peak intensity of E2 high mode as shown in Raman shift spectra decreased with the introduction of Al-dopant and also proved the increase of defects concentration and the suppression of crystallization in Al-doped ZnO nanorods. Finally, the hysteresis loops revealed the room temperature ferromagnetism of both compositions. As compared with ZnO nanorods, Al-doped ZnO nanorods showed a remarkable increase of saturation magnetization due to the increase of crystal defects.
Surface Modification of Stainless Steel with Ti–Si–C Thin Films by Magnetron Sputtering Using Elemental Targets at Low Preparation Temperatures
Authors: Sonoda Tsutomu , Nakao Setsuo , Ikeyama Masami
Published: November 2013

The deposition of Ti–Si–C thin films by magnetron sputtering was examined at low preparation temperatures using elemental targets of titanium, silicon, and carbon to investigate the effects of substrate temperature on the formation of carbide compounds, such as TiC
x
and/or Ti3SiC2, and thereby on mechanical properties, such as hardness, and on physical properties, such as the electrical conductivity, of thin films. It was found that Ti–Si–C thin films with an excellent electrical conductivity of approximately 200 µΩ cm and a surface hardness larger than 10 GPa could be deposited at a temperature of 500 °C, which is much lower than conventional deposition temperatures, such as 800 °C. Thus, it is expected that this deposition process will be more useful for providing protective coatings for electrical friction contacts. Furthermore, the highest corrosion protection performance was observed in the stainless steel coated with the Ti–Si–C films at 500 °C. Therefore, it is also expected that the corrosion protective property of stainless steel substrates will be improved by coating with the thin films at a temperature of 500 °C, which is much lower than conventional deposition temperatures, such as 800 °C.
Enhancement of the Luminance Efficiency due to an Embedded Self-Assembled Monolayer in Organic Light-Emitting Devices
Authors: Kim Ki Tae , Jeon Young Pyo , Seo Hanmin , Noh Jaegeun , Kim Tae Whan
Published: November 2013

The electrical and optical properties of organic light-emitting devices (OLEDs) with and without a self-assembled monolayer (SAM) were investigated, and the effect of an embedded SAM was clarified. The contact angles of COOH-terminated alkanethiol SAMs were smaller than those of CH3-terminated alkanethiol SAMs. The operating voltage of OLEDs with COOH-terminated alkanethiol SAMs was 4.4 V lower than that with CH3-terminated alkanethiol SAMs. The luminance of OLEDs with COOH-terminated alkanethiol SAMs was higher than that with CH3-terminated alkanethiol SAMs. The enhancement of the luminance efficiency of OLEDs with COOH-terminated alkanethiol SAMs was attributed to the increase in hole injection due to a decrease in the chain length of the COOH-terminated alkanethiols, resulting in a better balance between the numbers of holes and electrons at an emitting layer in the OLEDs.
Electrical Bistability of Organic Bistable Devices Based on Colloidal CuInS2 Quantum Dots Embedded in a Poly(N-vinylcarbazole) Layer
Authors: Park Hun Min , Yun Dong Yeol , Kim Sang Wook , Kim Tae Whan
Published: November 2013

Organic bistable devices (OBDs) with CuInS2 (CIS) quantum dots (QDs) embedded in a poly(N-vinylcarbazole) (PVK) layer were fabricated by spin coating. Current–voltage (I–V) curves of Al/colloidal hybrid CIS QD-PVK/indium tin oxide devices at 300 K showed that the current bistability with an ON/OFF ratio of 1×103 is larger than that of OBDs without CIS QDs. The number of retention cycles of the ON and OFF states for the OBDs was above 1×105. The carrier transport mechanisms of the OBDs were described on the basis of the I–V results.
Optimization of Chemical Vapor Deposition Process for Reducing the Fiber Diameter and Number of Graphene Layers in Multi Walled Carbon Nanocoils
Authors: Lim Siew Ling , Suda Yoshiyuki , Takimoto Kotaro , Ishii Yuichi , Maruyama Koji , Tanoue Hideto , Takikawa Hirofumi , Ue Hitoshi , Shimizu Kazuki , Umeda Yoshito
Published: November 2013

Multi walled carbon nanocoils (MWCNCs) were synthesized by chemical vapor deposition (CVD) and the experimental parameters were optimized to reduce their fiber diameter. The conditions for the synthesis of the thinnest MWCNC in this experiment were as follows: reaction temperature, 700 °C; C2H2/N2pressure, 0.67 kPa; and C2H2/N2ratio, 0.01. A low C2H2gas flow rate and a low partial gas pressure were important in reducing the fiber diameter. The reaction temperature affected both the MWCNC fiber diameter and purity, which depends on the content of MWCNCs and multi walled carbon nanotubes (MWCNTs). At high temperatures (≥750 °C), MWCNTs were predominant and their crystallinity increased, which was confirmed by the detection of the radial breathing mode and high intensity ratios of the G peak to the D peak in the Raman spectra. By contrast, MWCNCs were produced preferentially at low temperatures (approximately 700 °C). Transmission electron microscopy showed that the fiber diameter of the thinnest MWCNC was less than 5 nm at both the helix and tip and that the thinnest MWCNC had a triple walled structure. Under optimized conditions, the vacuum deposition of a thin film of Sn on a Si substrate and the mounting of Fe catalyst supported zeolite on a Sn/Si substrate effectively increased MWCNC purity. MWCNC purity was improved by up to 30%, which is the highest purity we have observed thus far.
Effect of Photoelectrode with Phosphor-Containing TiO2 Layer for Dye-Sensitized Solar Cells
Authors: Shin Seong Gwan , Kim Kyung Hwan , Bark Chung Wung , Choi Hyung Wook
Published: November 2013

Dye-sensitized solar cells (DSSCs) are composed of a dye-adsorbed nanoporous TiO2 layer on a fluorine-doped tin oxide (FTO) glass substrate, redox electrolytes, and a counter electrode. The phosphor is introduced into the TiO2 layer electrode in a DSSC. The content of phosphor-containing in the TiO2 paste is varied from 0.25 to 5.00 wt %. The synthesized TiO2 paste is deposited on FTO glass using a doctor blade. The conversion luminescence process of phosphor, increases both the light harvesting efficiency and the photocurrent. Using the 0.5 wt % Ba3Si6O12N2:Eu2+-containing TiO2 electrode, the light-to-electric-energy conversion efficiency of the DSSCs reaches 4.61% under simulated solar light irradiation at 100 mW/cm-2, which is an increase by a factor of 1.41 compared with that of the DSSCs without Ba3Si6O12N2:Eu2+.
Improvement in the Characteristics of Electric Double Layer Capacitor Using a Mixture of Arc Black and Carbon Nanoballoon
Authors: Okabe Yuta , Izumi Harutaka , Suda Yoshiyuki , Tanoue Hideto , Takikawa Hirofumi , Ue Hitoshi , Shimizu Kazuki
Published: November 2013

Carbon nanomaterials with different structures were mixed for an electric double layer capacitor (EDLC) electrode. We used two kinds of carbon nanomaterial: arc black (AcB) and a carbon nanoballoon (CNB). Arc black was synthesized by arc discharge. CNB was produced by heating the prepared AcB at 2400 °C. AcB mostly consists of an amorphous component and has a large specific surface area. On the other hand, CNB has a graphitic surface and a high conductivity. To utilize their characteristics, AcB and CNB were used as the main materials of the EDLC electrode in weight ratios of 1:1, 2:1, and 1:2. The obtained EDLC electrode was filled with 1 M H2SO4as the electrolyte. As a result, by mixing AcB and CNB, both the power and energy densities became higher than those of AcB or CNB alone. The EDLC mixed in 1:1 weight ratio of AcB and CNB showed the highest performance, with a higher electric power density than activated carbon (AC).
Field Emissions from Organic Nanorods Armored with Metal Nanoparticles
Authors: Suzuki Toshiya , Ishikawa Kenji , Takeda Keigo , Kondo Hiroki , Sekine Makoto , Hori Masaru
Published: November 2013

We report the fabrication of organic nanorods with a diameter of approximately 10 nm and a height of 106.8 nm (a high aspect ratio of 10.5) armored by Pt nanoparticles. Our results demonstrate that Pt particles deposited by metalorganic supercritical chemical fluid deposition (MOCFD) covering the entire deposition area play important roles in not only etch resistance, especially in protecting the sidewalls, but also the formation of electroconductive Pt/C composites, which were found to have field emission properties.
Preparation of Cu2ZnSnSe4 Absorber Layer by Nonvacuum Method
Authors: Liu Shang-En , Lin Yu-Hsuan , Huang Hou-Ying
Published: November 2013

Cu2ZnSnSe4 (CZTSe) was prepared by a nonvacuum, solution-based method, and used as an absorber layer in CZTSe solar cells. Copper(II) acetate monohydrate, zinc(II) acetate dehydrate, and tin(II) chloride dihydrate were used as the starting materials of the sol–gel method, and 2-methoxyethanol and monoethanolamine were used as the solvent and stabilizer, respectively. The precursor solution was deposited on Mo-coated soda lime glass (SLG) by spin-coating, then annealed at 570 °C in selenium atmosphere to convert it into the CZTSe absorber layer. The synthesized CZTSe absorber layer phase was identified by X-ray diffraction (XRD) and Raman spectrum analyses. By increasing the number of spin-coating/drying cycles, the CZTSe absorber layer thickness was increased and resulted in a current density increase in the current–voltage curve. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were carried out to confirm the absorber layer thickness and metal ratios. The highest efficiency of the solar cell was 1.08% with a 1.45 µm absorber layer.
Analysis of On-State Gate Current of AlGaN/GaN High-Electron-Mobility Transistor under Electrical and Thermal Stresses
Authors: Hayashi Kazuo , Sasaki Hajime , Oishi Toshiyuki
Published: November 2013

We have analyzed the on-state gate current of an AlGaN/GaN high-electron-mobility transistor (HEMT) by applying electrical and thermal stresses. The gate current shows a positive temperature dependence and its activation energy is less than the gate Schottky barrier height. This indicates that the gate current is a thermionic field emission and flows through a thinned AlGaN Schottky depletion layer by a tunneling or hopping mechanism. The depletion layer is considered to be thinned by the crystal defects created in the gate fabrication process. On the other hand, we have found that the gate current is decreased by applying a high electrical power under a high thermal stress. Strong electroluminescence can be observed by applying stress. These experimental results imply that the crystal defects are annealed out by the recombination-enhanced defect reaction mechanism induced by generated hot carriers. Therefore, the gate current is decreased by the reductions in the tunneling and hopping probability due to the expansion of the depletion layer.
Growth, Electrical Characterization, and Electroluminescence of GaN/SiC Heterojunction Diodes and Bipolar Transistors Fabricated on SiC Off-Axis Substrates
Authors: Miyake Hiroki , Amari Koichi , Kimoto Tsunenobu , Suda Jun
Published: November 2013

The growth, electrical characterization, and electroluminescence (EL) of GaN/SiC heterojunction bipolar transistors (HBTs) are presented. GaN grown on off-axis SiC by molecular beam epitaxy showed step bunching owing to the large off-angle of SiC substrates, which contributed to the annihilation of edge dislocations. We investigated the impact of base doping concentration and SiC polytype (4H and 6H) on the characteristics of GaN/SiC heterojunction diodes. By utilizing a reduced doping concentration of 1×1018 cm-3 instead of 1×1019 cm-3, we suppressed the tunneling current via interface traps, resulting in an improved rectifying behavior in the diodes. Capacitance–voltage (C–V) and EL characteristics revealed that the band lineup of GaN/SiC is of type II, and 6H-SiC is better for electron injection. In accordance with diode characteristics, the fabricated GaN/SiC HBTs showed an improved common-base current gain of 0.03 by employing a reduced base doping concentration of 1×1018 cm-3 and 6H-SiC, whereas a current gain below 1×10-4 was obtained in the HBTs with a base doping concentration of 1×1019 cm-3.
Functionalization of Multiwalled Carbon Nanotubes by Solution Plasma Processing in Ammonia Aqueous Solution and Preparation of Composite Material with Polyamide 6
Authors: Shirafuji Tatsuru , Noguchi Yohei , Yamamoto Taibou , Hieda Junko , Saito Nagahiro , Takai Osamu , Tsuchimoto Akiharu , Nojima Kazuhiro , Okabe Youji
Published: November 2013

Solution plasma processing (SPP) has been performed on multiwalled carbon nanotubes (MWCNTs) in ammonia aqueous solution. The MWCNTs, which do not disperse in aqueous solution, uniformly dispersed after the SPP. Only 2 h was required to obtain 10 g of the dispersed MWCNTs, while 7 days and additional chemicals were required for 185 mg in a previous study. The X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy of the SPP-treated MWCNTs revealed that nitrogen- and oxygen-containing groups are formed on the MWCNTs. Serious damage to the MWCNT structure was not observed in the Raman spectrum or transmission electron microscopy images of the SPP-treated MWCNTs. The composite materials prepared using polyamide 6 with the SPP-treated MWCNTs showed better tensile, bending, and impact strength than those prepared with nontreated MWCNTs.
Plasmon Absorbance of SiO2-Wrapped Gold Nanoparticles Selectively Coupled with Ti Substrate Using Porter Protein
Authors: Saijo Satoshi , Ishikawa Yasuaki , Zheng Bin , Okamoto Naofumi , Yamashita Ichiro , Uraoka Yukiharu
Published: November 2013

We developed a technique of placement of gold nanoparticles onto Si and glass substrates without aggregation using a porter–protein coupling method, and measured the optical characteristics of the substrates. We found that plasmon absorption can be maintained by SiO2-wrapped gold nanoparticles. This simple method enables the observation of the plasmon absorption of the sample coated with nanoparticles with the desired size at the designed positions.
Annealing Temperature Dependence of the Nanosized Pits on Poly(methyl methacrylate) Surface
Authors: Wu Ruixiang , Chen Ruiyun , Gao Yan , Zhang Guofeng , Xiao Liantuan , Jia Suotang
Published: November 2013

We report the annealing-temperature-dependent evolution of nanosized pits on a poly(methyl methacrylate) film spin-coated on a glass substrate. The pits are formed on the polymer surface as the toluene solvent evaporates rapidly. The depth and width of the pits are measured by atomic force microscopy after the film is annealed at ambient temperature, below and above the glass transition temperature (105 °C) of the polymer, respectively. Compared with the statistical results obtained at ambient temperature, the pits are shallow and narrow on the film annealed at 75 °C as molecular vibration expands the film. However, it is found that the pits are deeper and wider on the film annealed at 120 °C than on the films annealed at the other two temperatures, which results from the evaporation of the inner residual toluene in the polymer film.
Design of KEK Test Machine for Mo Isotope Separation Based on Ion Cyclotron Resonance Plasma Separation
Authors: Ohmi Kazuhito , Inagaki Takao , Kichimi Hiromichi , Takagi Akira , Tanaka Kenichi , Suzuki Tatsuya , Shibata Tokushi , Fujii Yasuhiko
Published: November 2013

We discuss the design of a KEK test machine for Mo isotope separation based on the ion cyclotron resonance plasma separation process (KEK-ICR-PSP). The test machine consists of a superconducting magnet of 1.5 T, an Ar sputtering plasma chamber, a helical coil of 30-cm-diameter and 60 cm length, providing an ICR heating field of about 20 V/m, an isotope collector, and RF power systems. The yield and purity of 100Mo and 98Mo are evaluated using a dedicated Monte Carlo simulation program, KEK-ICR-SIM. They are strongly affected by the energy spectra of Mo ions from the sputtering plasma chamber, which can be investigated with the test machine.
Mechanisms of Local Planarization Improvement Using Solo Pad in Chemical Mechanical Polishing
Authors: Isobe Akira , Yokoyama Toshiyuki , Komiyama Takashi , Kurokawa Syuhei
Published: November 2013

The mechanism of local planarization improvement using a solo pad in chemical mechanical polishing (CMP) was investigated, and the pad surface temperature was found to be the key factor. The use of a solo pad results in better planarity than that of a stacked pad under the same process conditions. When Cu CMP evaluation was conducted at various platen temperatures, a good correlation of local planarity to pad surface temperature was confirmed regardless of the pad type. Planarity improved when the pad surface temperature was lowered, and the solo pad had a lower temperature than the stacked pad at the same platen temperature. It is considered that the solo pad has a higher heat conductance than the stacked pad, so that heat generated during polishing is transferred to the platen more easily through the solo pad than through the stacked pad. The reason for the better planarity with the lower pad surface temperature was explained by the change in pad elasticity by the temperature.
New Model of Defect Formation Caused by Retainer Ring in Chemical Mechanical Polishing
Authors: Isobe Akira , Komiyama Takashi , Kurokawa Syuhei
Published: November 2013

Defect formation by retainer ring pressure in chemical mechanical polishing (CMP) was investigated. It was found that a higher retainer ring pressure causes more defects. The mechanism underlying this finding was considered to be the agglomeration of abrasive particles mixed with polished polymers from the retainer ring. Such agglomeration is accelerated by increasing the retainer ring pressure. This ring pressure exerts stress onto particles and also polishes the polymers from the ring. Lowering the retainer ring pressure and also changing the ring material from polymers, which are easy to polish, to tough materials are effective for minimizing the density of defects in CMP.
Proposal of New Polishing Mechanism Based on Feret's Diameter of Contact Area between Polishing Pad and Wafer
Authors: Isobe Akira , Akaji Masatoshi , Kurokawa Shuhei
Published: November 2013

Relationships between pad surface characteristics and polishing rate are investigated. New parameter “total Feret's diameter” of contact portions is proposed as a key parameter, which shows simple correlation to the polishing rate. Feret's diameter is a projection length of a contact shape. Based on Feret's diameter, a new polishing model is proposed in which material is removed by abrasive particles existing at periphery of the pad contact portions, not on them. When a pad contact portion moves on a wafer, abrasive particles gathers at the front end of the contact portion and they remove the wafer surface material by absorbing molecules on their surface. Number of particles at contact portion is considered to be proportional to Feret's diameter.
Observation of Encapsulated Bubble Oscillations Driven by Ultrasound
Authors: Liang Jin-Fu , Chen Wei-Zhong , Shao Wei-Hang , Zhou Chao , Du Lian-Fang , Jin Li-Fang
Published: November 2013

Using a long-distance microscope imaging system and a technique using a movable lock-in pulse laser, optical measurement demonstrated the behavior of a SonoVue® contrast agent microbubble exposed to a low-amplitude, 478 kHz ultrasound field. The microbubble consisted of the gas SF6 encapsulated by a polymer shell. Eighty-four frames of a microbubble oscillating in response to an ultrasound field were captured in one acoustic cycle. The experimental data on microbubble radius were fitted by the numerical calculations of the Hoff, Yasui, and Keller–Miksis models. The results showed good agreement between the data and the theoretical calculation of the Hoff model using our experimental parameters. In addition, the spectral analysis of the time-radius data indicated that the relative intensity of the second harmonic increased with the increase in acoustic pressure amplitude.
Novel Technique for Improving the Signal-to-Background Ratio of X-ray Absorption Near-Edge Structure Spectrum in Fluorescence Mode and Its Application to the Chemical State Analysis of Magnesium Doped in GaN
Authors: Yonemura Takumi , Iihara Junji , Saito Yoshihiro , Ueno Masaki
Published: November 2013

A novel measurement technique for an X-ray absorption near-edge structure (XANES) for magnesium (Mg) doped in gallium nitride (GaN) has been developed. XANES spectra from Mg at very low concentrations of 1 ×1018/cm3 doped in GaN have successfully been obtained by optimizing the region of interest (ROI) and by using highly brilliant synchrotron radiation X-rays of SPring-8. The ROI is the limited energy region from an X-ray fluorescence spectrum to elicit signals of particular atoms. Using this new technique, we have investigated the effect of the annealing process for Mg-doped GaN on the XANES spectra. It has been found that the XANES spectra of Mg significantly changed as the annealing temperature increased. This indicates that the local structure around Mg atoms in GaN was modified by the annealing process.
Oxide Thin-Film Transistors Fabricated Using Biodegradable Gate Dielectric Layer of Chicken Albumen
Authors: Jeon Da-Bin , Bak Jun-Yong , Yoon Sung-Min
Published: November 2013

An oxide thin-film transistor (TFT) using chicken albumen as gate dielectric on paper substrate was demonstrated. Chicken albumen, which was directly extracted from chicken egg white, was deposited as gate dielectric layer. An In–Ga–Zn–O was chosen as an active channel. The TFT feasibilities were successfully confirmed, in which channel mobility and subthreshold slope of the TFT were 6.48 cm2 V-1 s-1 and 1.28 V/s, respectively. This is the first report on the device configuration combining the biodegradable gate insulator and oxide semiconducting channel.
Ge2Sb2Te5 Film Fabrication by Tellurization of Chemical Vapor Deposited GeSb
Authors: Suda Kohei , Uno Tomohiro , Miyakawa Tatsuya , Sawamoto Naomi , Machida Hideaki , Ishikawa Masato , Sudoh Hiroshi , Ohshita Yoshio , Ogura Atsushi
Published: November 2013

This paper describes stoichiometric Ge2Sb2Te5 (GST) film fabrication by the process based on chemical vapor deposition (CVD). GST films were fabricated by tellurization after GeSb CVD. This two step process enabled to fill high aspect holes. By applying appropriate precursors and process temperature, the surface morphology of the GST film was significantly improved. The moderate tellurization reaction process might contribute GST formation with maintaining the amorphous structure of the CVD GeSb. We believe this technique is useful for phase change memory application.
Early Stages of Sn-Doped In2O3 Film Growth on Amorphous SiO2 Surfaces Observed by Atomic Force Microscopy and Transmission Electron Microscopy
Authors: Sato Yasushi , Oka Nobuto , Nakamura Shin-ichi , Shigesato Yuzo
Published: November 2013

The early stages of Sn-doped In2O3 (ITO) film growth on amorphous SiO2 (a-SiO2) surfaces were observed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). AFM measurements clearly showed that the surface morphologies of the ITO films (3–6 nm in thickness) possessed an extended hill-and-valley structure. TEM analysis revealed that small ITO islands on the a-SiO2 surface could aggregate, resulting in the formation of larger ITO islands approximately 15–30 nm in diameter. The combined results indicate that the ITO film growth on a-SiO2 surfaces is similar to that on glass surfaces.
VERFAHREN: Urkundenprozess bei rückständigen Mietnebenkosten
Authors: Schmid Michael J.
Published: November 2013

Der Urkundenprozess bietet für den Kläger zahlreiche Vorteile: Straffung des Verfahrens, Beschränkung der Beweismittel für Einwendungstatsachen des Beklagten sowie der Erhalt eines Urteils, das ohne Sicherheitsleistung vorläufig vollstreckbar ist. Grundsätzlich ist der Urkundenprozess auch im Mietnebenkostenverfahren möglich. Der folgende Beitrag geht auf Praktikabilität und Risiken dieses besonderen Streitgegenstandes ein.
VERSICHERUNGSRECHT: Die aktuelle Entwicklung in der Rechtsprechung zur quotalen Leistungskürzung
Authors: Böhm Falk H. , Nugel Michael
Published: November 2013

Die quotale Leistungskürzung ist als zentraler Punkt der VVG-Reform bereits durch eine Vielzahl an Urteilen umgesetzt worden. Im Rahmen der jährlichen Übersicht zu diesem Themenkreis werden mit diesem Beitrag die wesentlichen Entwicklungen bei den wichtigsten Fallgruppen der Kraftfahrt- und Sachversicherung dargestellt.
MIETRECHT: Die Einrede des nicht erfüllten Vertrags bei nach Überlassung auftretenden, behebbaren Mietmängeln
Authors: Conrad Christian
Published: November 2013

Tritt an Mietobjekten ein Mangel auf, wird hierauf in der Praxis überwiegend mit dem Instrument der Mietminderung reagiert. Der folgende Beitrag verdeutlicht, dass daneben auch stets an ein Instrument des allgemeinen Schuldrechts, nämlich an die Einrede des nicht erfüllten Vertrags (§ 320 BGB), gedacht werden sollte. Nur so kann optimal, umfassend und praxisgerecht auf die gegebene tatsächliche Situation sowie die Wünsche des mietenden Mandanten reagiert werden. Aber auch Vermieter sind gut beraten, vor Ausspruch einer Kündigung wegen Zahlungsverzugs Existenz und Auswirkung dieser Einrede zu überprüfen.
A systematic 2‐D investigation into the mantle wedge's transient flow regime and thermal structure: Complexities arising from a hydrated rheology and thermal buoyancy
Authors: Le Voci G. , Davies D. R. , Goes S. , Kramer S. C. , Wilson C. R.
Published: November 2013

Arc volcanism at subduction zones is likely regulated by the mantle wedge's flow regime and thermal structure and, hence, numerous studies have attempted to quantify the principal controls on mantle wedge conditions. In this paper, we build on these previous studies by undertaking a systematic 2‐D numerical investigation into how a hydrated rheology and thermal buoyancy influence the wedge's flow regime and associated thermal structure. We quantify the role of a range of plausible: (i) water contents (0–5000 H/106Si); (ii) subduction velocities (2–10 cm/yr); and (iii) upper‐plate ages (50–120 Myr), finding that small‐scale convection (SSC), resulting from Rayleigh‐Taylor instabilities, or drips, off the base of the overriding lithosphere, is a typical occurrence. The morphology of SSC varies with viscosity and subduction parameters, with drips at their most prominent when subduction velocities and wedge viscosities are low. Our results confirm that high subduction velocities and wedge viscosities promote a dominantly corner‐flow regime, and strong upper‐plate erosion below the arc region. By contrast, we find that back‐arc upper‐plate erosion by SSC is largely controlled by wedge viscosity, occurring when: (i) viscosities are < 5·1018 Pa s; and (ii) the length of the upper plate, available for destabilization, exceeds the characteristic wavelength of instabilities. Thus, if hydrous weakening of wedge rheology extends at least 100–150 km from the trench, our 2‐D models predict an unstable flow regime, resulting in temperature fluctuations of 50–100 K, which are sufficient to influence melting and the stability of hydrous minerals.