bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Local Bending Stress Effect on Complementary Metal–Oxide–Semiconductor Characteristics in Thinned Si Chip for Chip-to-Wafer Three-Dimensional Integration
Authors: Kino Hisashi , Bea Ji Choel , Murugesan Mariappan , Lee Kang Wook , Fukushima Takafumi , Koyanagi Mitsumasa , Tanaka Tetsu
Published: April 2013

A three-dimensional LSI (3D-LSI) that vertically stacks Si chips with a number of through-silicon vias (TSVs) and metal microbumps has attracted much attention recently. However, there are some issues to be resolved in the fabrication of 3D-LSI. In this study, we investigated impacts of local bending stress on the performance of a complementary metal–oxide–semiconductor (CMOS) circuit fabricated in a thinned Si chip. First, we proposed a novel method and a test structure to easily induce the local bending stress in the thinned Si chip. Then, we evaluated the distribution of the local bending stress and its effects on the electrical characteristics of metal–oxide–semiconductor field-effect transistor (MOSFETs). As a result, we observed the degradations of the MOSFET currents and CMOS inverter switching behaviors in accordance with the chip local bending. Our experimental results obviously indicate that the local bending stress caused large fluctuations in the performance of the circuit fabricated in the thinned Si chip.
Influence of Structural Parameters on Electrical Characteristics of Schottky Tunneling Field-Effect Transistor and Its Scalability
Authors: Wu Yan , Dou Chunmeng , Wei Feng , Kakushima Kuniyuki , Ohmori Kenji , Ahmet Parhat , Watanabe Takanobu , Tsutsui Kazuo , Nishiyama Akira , Sugii Nobuyuki , Natori Kenji , Yamada Keisaku , Kataoka Yoshinori , Hattori Takeo , Iwai Hiroshi
Published: April 2013

The influence of structural parameters, including the Schottky barrier height for electron (φBn) and channel doping (N
a), on the electrical characteristics of a scaled Schottky barrier tunneling FET (SBTFET) have been clarified by numerical device simulation. The thermionic emission current (I
TH) as well as the tunneling current (I
TN) have been considered as the main electron injections at the source edge. Simulation results have revealed that the main conduction is I
TN in the region near and above the threshold voltage (V
th). As tunneling probability is determined by φBn and the width of the triangular potential barrier at the source edge, a lower φBn with higher N
a results in a better subthreshold swing (SS) with high on-state drive current (I
ON) at a gate length (L
g) of 50 nm. With L
g scaling down to 10 nm, however, a lower φBn has shown an increased off-state leakage current (I
OFF) due to the short-channel effect (SCE), while a larger φBn can suppress the I
OFF at the cost of I
ON. Therefore, considering SS with I
ON and I
OFF ratio, it can be concluded that an optimum φBn exists for short-channel devices. The SBTFET showed good subthreshold performance and higher I
ON/I
OFF than the conventional silicon-on-insulator (SOI) MOSFET in 10 nm region with the Schottky barrier height optimization.
Analysis and Modeling of Geometry Dependent Thermal Resistance in Silicon-on-Insulator Metal–Oxide–Semiconductor Field-Effect Transistors
Authors: Zhou Xingye , Inoue Takuya , Kitamura Masashi , Matsuura Kai , Miyake Masataka , Iizuka Takahiro , Umeda Takuya , Kikuchihara Hideyuki , Mattausch Hans Juergen , He Jin , Miura-Mattausch Mitiko
Published: April 2013

It is demonstrated that the self-heating effect easily causes elevated thermal equilibrium condition within the active device for thin substrate MOSFETs. This leads to a non-linearity of the thermal resistance, which originally is a material specific constant. A compact model for describing the observed effective nonlinear thermal resistance has been developed which captures the device geometry effects as well as the bias condition dependences.
Squareness Control in Polarization–Electric Field Hysteresis Curves in Rhombohedral Pb(Zr,Ti)O3 Films
Authors: Sumi Akihiro , Oikawa Takahiro , Morioka Hitoshi , Okamoto Shoji , Yokoyama Shintaro , Watanabe Takayuki , Ehara Yoshitaka , Funakubo Hiroshi
Published: April 2013

Squareness in polarization–electric field hysteresis loops of (100)-oriented epitaxial and fiber-textured rhombohedral Pb(Zr,Ti)O3 films prepared on (100) SrTiO3 and (100) Si substrates, respectively, was investigated as a function of temperature. The ratio of remanent polarization to saturation polarization (P
r/P
sat) decreased with increasing temperature for all films. It depends on the kind of substrates and the remained strain in the in-plane orientation. These data suggest that the existing strain in the films possibly affects the temperature dependence of the P
r/P
sat ratio.
Filament Evolution during Set and Reset Transitions in Oxide Resistive Switching Memory
Authors: Ielmini Daniele , Balatti Simone , Larentis Stefano
Published: April 2013

Bipolar resistive switching memory (RRAM) relies on ion migration effects taking place at a conductive filament (CF). Understanding the evolution of the CF during set and reset transitions is essential for predicting RRAM scalability and for developing new methods for storage and computation. This work describes the evolution of the CF during bipolar resistive switching through numerical simulations of ion drift/diffusion. The defect distribution profile for increasing current after set transition and for increasing voltage during set transition are shown. Finally, the asymmetric shape of the CF is evidenced through polarity-dependent experiments and explained through numerical simulations.
Forward and Reverse Biasing in Resistive Memories for Fast, Disturb-Free Read, and Verify
Authors: Iwasaki Tomoko Ogura , Ning Sheyang , Takeuchi Ken
Published: April 2013

The potential of resistive random access memory (ReRAM) to provide high speed operation is held back by the need to verify during set/reset, and sensitivity to read disturb. 50 nm HfO2 cells are measured for disturb in forward and reverse directions, and at 25 and 85 °C. Two circuit proposals provide speed and reliability improvement. First, bipolar verify reduces write time. If the verify direction matches the set/reset direction, read voltage can be increased, which reduces signal development time, and eliminates the need to switch the highly capacitive source line voltage. Secondly, reverse read with dynamic write-back provides fast, disturb-free read. A margin-check is performed in parallel to normal reverse-read. Disturb of the low resistance state is monitored, and then, if needed, set write-back occurs. Based on disturb data, write-back occurs infrequently, after ∼5×109 reads. By these two proposals, write time can be reduced by 3× and 5× faster read with disturb immunity can be achieved.
Research of Bulk Erase Operation in Vertical Three-Dimensional Cell Array Architecture
Authors: Yang Hyung-jun , Lee Gae-hun , Kim Kyeong-rok , Song Yun-heub
Published: April 2013

A bit-cost scalable (BiCS) NAND flash memory with a bulk erasing method is investigated in view of cell characteristics and uniformity. The proposed cell array has an additional electrode layer for a bulk erase operation in the middle of a vertical channel string cell. Here, under a bias condition of 20 V, a programming threshold voltage of 4.2 V at 1 ms and an erasing threshold voltage of V
th = -1.5 V at 10 ms are confirmed, which is acceptable for flash memories. Furthermore, the shielding transistor close to an erase electrode is also investigated, which gives better erase characteristics for the cells adjacent to the erase electrode. From this result, we expect that a bulk erasable-BiCS technology with a shielding transistor can be a candidate three-dimensional (3D) NAND flash memory.
False Operation of Static Random Access Memory Cells under Alternating Current Power Supply Voltage Variation
Authors: Sawada Takuya , Takata Hidehiro , Nii Koji , Nagata Makoto
Published: April 2013

Static random access memory (SRAM) cores exhibit susceptibility against power supply voltage variation. False operation is investigated among SRAM cells under sinusoidal voltage variation on power lines introduced by direct RF power injection. A standard SRAM core of 16 kbyte in a 90 nm 1.5 V technology is diagnosed with built-in self test and on-die noise monitor techniques. The sensitivity of bit error rate is shown to be high against the frequency of injected voltage variation, while it is not greatly influenced by the difference in frequency and phase against SRAM clocking. It is also observed that the distribution of false bits is substantially random in a cell array.
Characterization of Electroluminescence from One-Dimensionally Self-Aligned Si-Based Quantum Dots
Authors: Takami Hiroki , Makihara Katsunori , Ikeda Mitsuhisa , Miyazaki Seiichi
Published: April 2013

We have demonstrated self-assembling formation of one-dimensionally self-aligned Si-based quantum dots (QDs) structures and applied them to an active layer of light emitting diodes (LEDs) with a semitransparent Au gate. Under forward bias conditions over threshold biases as low as ∼1.2 and ∼-2.0 V for LEDs formed on n- and p-Si(100), respectively, stable electroluminescence (EL) was observable in the near-infrared region at room temperature. The observed EL spectra could be deconvoluted into mainly two component peaks at ∼1140 and ∼1100 nm that originated from lower and upper dots, respectively, where both spectrum intensities showed a power-law relationship of the EL intensity with applied bias and input power. Notice that the slope of the component peak for the lower dots was larger than that for the upper dots, indicating that holes were stably stored in the lower dots due to a deep potential well. In fact, when an AC bias as low as ∼6.4 V (DC at 2.0 V) was applied to the LEDs with an Au gate formed on the n-Si(100), a single component peak for the lower dots was detected, indicating electron–hole recombination in the lower dots caused by alternate carrier injection from the Si(100) substrate.
Si Waveguide-Integrated Metal–Semiconductor–Metal and p–i–n-Type Ge Photodiodes Using Si-Capping Layer
Authors: Fujikata Junichi , Miura Makoto , Noguchi Masataka , Okamoto Daisuke , Horikawa Tsuyoshi , Arakawa Yasuhiko
Published: April 2013

We studied Si waveguide-integrated metal–semiconductor–metal (MSM) and p–i–n-type Ge photodiodes (Ge-PDs), using a Si-capping layer. As for an MSM Ge-PD, the Schottky barrier height was increased up to 0.44 V by applying a 8–20 nm Si-capping layer, and a very low dark current density of approximately 0.4 nA/µm2 was achieved with a high responsivity of 0.8 A/W. In addition, a small electrode spacing of 1 µm realized high-speed photodetection of 20 Gbps. As for a p–i–n-type Ge-PD, by applying a 10–20 nm Si capping layer, the contact resistance between a metal electrode of Ti/TiN/Al and n+-Si capping layer was successfully reduced to 1×10-5 Ω·cm2. A 45 GHz bandwidth was obtained with a low dark current density of 0.8 nA/µm2. Moreover, a more than 20 GHz bandwidth was achieved with zero-bias voltage. In the case of zero-bias voltage operation, a 3 dB bandwidth was a little affected by input power, which would originate from the photocarrier screening effect on the built-in electric field.
Single Photon Generation from an Impurity Center with Well-Defined Emission Energy in GaAs
Authors: Zhang Liao , Ikezawa Michio , Mori Tatsuya , Umehara Shintaro , Sakuma Yoshiki , Sakoda Kazuaki , Masumoto Yasuaki
Published: April 2013

We studied optical properties of isoelectronic traps in nitrogen δ-doped GaAs by micro-photoluminescence (µ-PL) spectroscopy. We found that these nitrogen impurity centers (NNA) emit photons with nearly identical emission energy at 1475 meV and polarization direction. Furthermore, single photon generation from a single impurity center was confirmed by a strong photon antibunching under the continuous optical excitation at 5 K. Our results suggest that the nitrogen impurity center in GaAs might be well suited for the energetically-defined single photon source for the quantum information application.
Gain Measurement of Highly Stacked InGaAs Quantum Dot Laser with Hakki–Paoli Method
Authors: Tanoue Fumihiko , Sugawara Hiroharu , Akahane Kouichi , Yamamoto Naokatsu
Published: April 2013

A 147-µm-long cavity laser diode with 19 InGaAs quantum dot layers was fabricated by the ultrahigh-rate molecular beam epitaxial growth technique, and its gain properties were investigated using the Hakki–Paoli method below the threshold current (I
th) of 111.5 mA. At an injection current of 100.3 mA (0.9I
th), the positive net modal gain was in the range between 1005 and 1043 nm, corresponding to a photon energy of 45 meV. The maximum net modal gain and maximum modal gain were 46.5 and 60.5 cm-1, respectively. A differential net modal gain of as high as 3.8 cm-1/mA was observed at 0.77 times the threshold current. No gain saturation appeared below the threshold current, and injection currents higher than 78.4 mA (≈0.7I
th) were required to obtain a net modal gain.
Output Characteristics of a Semiconductor Laser Diode with Double Ring Cavities and a Y-Junction Coupler
Authors: Shih Ming Chang , Sun Yu Chin , Fan Shin Wei
Published: April 2013

We demonstrated an InGaAlP multiple-quantum-well semiconductor laser diode with double circular ring cavities and its output characteristics. It was found that the optical confinement factor of the ridge waveguide plays an important role in the output emission of this device, and superluminescence emission can be achieved with a low-confinement ridge waveguide. Spatial solitons can be generated in the ridge waveguide of 8 µm width and 0.9 µm depth owing to a nonlinear photorefractive effect. When the injection current in the circular ring cavity increases, the feedback light from the Y-junction coupling section continuously enhances the excitation through the soliton waveguide. In addition, the double-ring cavities provide wavelength filtering and feedback control from the Y-junction coupling section to achieve a superluminescent mode or lasing mode output operation. Results of light–current (L–I) and spectral measurements of the devices with various waveguide properties were presented to explore the mechanism of the output from this circular ring laser diode.
Luminescence Properties of Rare-Earth-Doped Thiosilicate Phosphors on Silicon Substrate
Authors: Nanai Yasushi , Sakamoto Yu , Okuno Tsuyoshi
Published: April 2013

The luminescence properties of rare-earth-doped thiosilicate phosphors are reported. These thiosilicate materials are fabricated in phosphor layers on silicon substrates. For Eu2+-doped calcium thiosilicate, yellow (560 nm) and red (650 nm) bands are obtained in the photoluminescence spectrum, which is almost the same as that for the corresponding powder sample. The energy transfer efficiency from Eu2+to Er3+in Eu2SiS4:Er3+on Si substrates is improved by optimization of the annealing conditions. In addition, the insulation of electroluminescence devices using BaSi2S5:Eu2+on silicon-on-insulator substrates is improved using a high-dielectric-constant polymer as a transparent insulating layer.
A Comprehensive Study on the Optical Properties of Thin Gold-Doped Rhenium Disulphide Layered Single Crystals
Authors: Huang Chih-Cheng , Kao Chen-Chia , Lin Der-Yuh , Lin Chih-Ming , Wu Fan-Lei , Horng Ray-Hua , Huang Ying-Sheng
Published: April 2013

We present a comprehensive study on the optical properties of gold-doped rhenium disulphide (ReS2:Au) layer crystal. Its anisotropic optical properties were studied by using the polarization-dependent optical absorption and photoconductivity (PC) measurements. Absorption measurements indicate that the absorption edge shifted toward high energy as the sample was slimmed down to a thin piece. For the first time, excitonic transitions have been observed by this method. The room temperature transition energies were evaluated to be 1.48 eV for E
1
ex and 1.516 eV for E
2
ex. E
1
ex exciton dominates the transition as the polarization is parallel to the b-axis of the layer crystal, while E
2
ex exciton is most present as the polarization is perpendicular. PC spectra are performed to check this anisotropic phenomenon. Thermoreflectance modulation (TR) and photoluminescence (PL) measurements have been performed in the temperature range of 42 to 300 K. The temperature dependence of the transition energies and broadening parameters were determined.
Performance Revelation and Optimization of Gold Nanocrystal for Future Nonvolatile Memory Application
Authors: Lin Chih-Ting , Wang Jer-Chyi , Huang Po-Wei , Chen Yu-Yen , Chang Li-Chun
Published: April 2013

The annealing effects on the gold nanocrystal (Au-NC) formation for memory application are proposed. At higher annealing temperatures, the memory window becomes larger owing to the high density of Au-NCs. The average size of the Au-NCs is approximately 5 nm, and the spaces between NCs tend to decrease with annealing temperature. Furthermore, the retention charge loss rate was optimized at 700 °C annealing formation and found to be dominated by the thermally activated and tunneling mechanisms. The high charge loss rate for the thermally activated mechanism shows no dependence on annealing temperature, while the low charge loss rate for the tunneling depends on the spaces between NCs. Besides, the activation energy of the thermally activated electron loss was low at a high Au-NC density, which can be attributed to the lateral electron migration between NCs. The endurance of the 700 °C annealed sample can sustain a memory window of approximately 1.1 V after 104 program/erase cycles.
Transparent Organic Thin Film Transistors Using an Oxide/Metal/Oxide Trilayer as Low-Resistance Transparent Source/Drain Electrodes
Authors: Su Shui-Hsiang , Wu Chung-Ming , Tsai Hsiang-Lin , Yokoyama Meiso
Published: April 2013

This work presents transparent pentacene-based organic thin film transistors (OTFTs) in which an oxide/metal/oxide trilayer provides low-resistance transparent source/drain electrodes. The device structure is glass/indium–tin oxide (ITO)/poly(methyl methacrylate) (PMMA)/pentacene/transparent source–drain electrode. The transparent source/drain electrode consists of a low-resistance metal, silver, that is sandwiched by a high-transmittance oxide, WO3. The structure of the transparent source–drain electrode is optimized by tuning the thickness of each layer. The optimized structure has a sheet resistance of 6.2 Ω/sq. and an optimum transmittance of 70% in the visible wavelength range of 380–780 nm. The pentacene-based OTFT employing optimized transparent source–drain electrode yields an output current (I
DS) of -7.08 µA, a field-effect mobility (µ) of 0.22 cm2 V-1 s-1, an on–off drain current ratio of 1.8×105, and a threshold voltage of -15.1 V. OTFTs in which WO3 (5 nm)/Ag (10 nm)/WO3 (30 nm) is used as the source/drain electrode greatly outperform OTFTs in which silver is utilized, because the work function of WO3/Ag/WO3 substantially exceeds that of silver.
Ultrathin Poly(4-vinylphenol) Interfacial Layer Evaporation for Low-Voltage Operation of Organic Field-Effect Transistors with HfO2 Gate Insulator
Authors: Ohmi Shun-ichiro , Kamino Kousuke , Ishiwara Hiroshi
Published: April 2013

Ultrathin poly(4-vinylphenol) (PVP) layer formation by evaporation was investigated for the first time to improve the pentacene/HfO2 interface characteristics in bottom-gate organic field-effect transistors (OFETs). 3–10-nm-thick PVP layers were successfully deposited by evaporation. It was found that the surface roughness of the PVP layer was remarkably decreased at the deposition temperatures of 50–100 °C both on SiO2 and HfO2 gate insulators. The obtained relative dielectric constants of the PVP layers deposited on SiO2 and HfO2 were 3.4 and 4.8, respectively. The mobility in the fabricated pentacene-based p-type OFETs with the HfO2 gate insulator was increased from 0.25 cm2 to 0.32 cm2 V-1 s-1 at the operation voltage of 2 V by the 5-nm-thick PVP interfacial layer deposited at 50 °C.
A Wearable Capacitive Sensor for Monitoring Human Respiratory Rate
Authors: Kundu Subrata Kumar , Kumagai Shinya , Sasaki Minoru
Published: April 2013

Realizing an untethered, low-cost, and comfortably wearable respiratory rate sensor for long-term breathing monitoring application still remains a challenge. In this paper, a conductive-textile-based wearable respiratory rate sensing technique based on the capacitive sensing approach is proposed. The sensing unit consists of two conductive textile electrodes that can be easily fabricated, laminated, and integrated in garments. Respiration cycle is detected by measuring the capacitance of two electrodes placed on the inner anterior and posterior sides of a T-shirt at either the abdomen or chest position. A convenient wearable respiratory sensor setup with a capacitance-to-voltage converter has been devised. Respiratory rate as well as breathing mode can be accurately identified using the designed sensor. The sensor output provides significant information on respiratory flow. The effectiveness of the proposed system for different breathing patterns has been evaluated by experiments.
Detection of Sub-Nano-Tesla Magnetic Field by Integrated Magnetic Tunnel Junctions with Bottom Synthetic Antiferro-Coupled Free Layer
Authors: Fujiwara Kosuke , Oogane Mikihiko , Nishikawa Takuo , Naganuma Hiroshi , Ando Yasuo
Published: April 2013

Arrays of 100×100 magnetic tunnel junctions (MTJs) connected in parallel and series were fabricated. A synthetic antiferro-coupled bottom free layer with a NiFe/Ru/CoFeB structure and MgO tunneling barrier were used to realize a high sensitivity, which is defined as TMR/2H

k
, where, TMR is the tunneling magnetoresistance ratio and H

k
is the magnetic anisotropy field of the free layer. To obtain a linear response of tunneling resistance against an applied external magnetic field, a double annealing process was carried out. From R–H curve measurements, the sensitivity of the 100×100 integrated MTJs was lower (8%/Oe) than that of a single MTJ (25%/Oe). However, a 1/30 decrease in noise power density was realized in the integrated MTJs. Consequently, a very small magnetic field of 0.29 nT was detected with the integrated MTJs.
Circuit-Level Model of Phase-Locked Spin-Torque Oscillators
Authors: Ahn Sora , Lim Hyein , Kim Miryeon , Shin Hyungsoon , Lee Seungjun
Published: April 2013

Spin-torque oscillators (STOs) are new oscillating devices based on spintronics technology with many advantageous features, i.e., nanoscale size, high tunability, and compatibility with standard silicon processing. Recent research has shown that two electrically connected STOs may operate as a single device when specific conditions are met. To overcome the limitation of the small output power of STOs, the phase-locking behavior of multiple STOs is hereby extensively investigated. In this paper, we present a circuit-level model of two coupled STOs considering the interaction between them such that it can represent the phase-locking behavior of multiple STOs. In our model, the characteristics of each STO are defined first as functions of applied DC current and external magnetic field. Then, the phase-locking condition is examined to determine the properties of the two coupled STOs on the basis of a theoretical model. The analytic model of two coupled STOs is written in Verilog-A hardware description language. The behavior of the proposed model is verified by circuit-level simulation using HSPICE with CMOS circuits including a current-mirror circuit and differential amplifiers. Simulation results with various CMOS circuits have confirmed the effectiveness of our model.
Triggering Mechanism for Neutron Induced Single-Event Burnout in Power Devices
Authors: Shoji Tomoyuki , Nishida Shuichi , Hamada Kimimori
Published: April 2013

Cosmic ray neutrons can trigger catastrophic failures in power devices. It has been reported that parasitic transistor action causes single-event burnout (SEB) in power metal–oxide–semiconductor field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). However, power diodes do not have an inherent parasitic transistor. In this paper, we describe the mechanism triggering SEB in power diodes for the first time using transient device simulation. Initially, generated electron–hole pairs created by incident recoil ions generate transient current, which increases the electron density in the vicinity of the n-/n+ boundary. The space charge effect of the carriers leads to an increase in the strength of the electric field at the n-/n+ boundary. Finally, the onset of impact ionization at the n-/n+ boundary can trigger SEB. Furthermore, this failure is closely related to diode secondary breakdown. It was clarified that the impact ionization at the n-/n+ boundary is a key point of the mechanism triggering SEB in power devices.
Spectroscopic Detection of Medium Range Order in Device Grade Hydrogenated Amorphous Silicon
Authors: Lucovsky Gerry , Parsons Greg , Zeller Daniel , Kim Jinwoo
Published: April 2013

This article addresses low defect densities in hydrogenated amorphous silicon, a-Si1-x
:H
x
with approximately 10 at. % bonded H, x∼0.1. Based low defect densities at mid-gap, ∼0.5 to 1×1016 cm-3, a-Si:H thin films have been integrated into photovoltaic (PV) devices and thin film transistors (TFT's). Amorphous Si (a-Si) thin films with no detectable bonded-H have been used as precursors for polycrystalline gate electrodes in microelectronic applications. PV and TFT alloys have been deposited by glow discharge (GD), remote plasma-enhanced chemical vapor deposition (RPECVD), and reactive magnetron sputtering (RMS) with different bonded-H content determined by deposition precursors and substrate temperatures. Two conditions are required for the lowest Si dangling bond densities: (i) a monohydride, Si–H, concentration of ∼10 at. % H, and (ii) deposition, and/or a post-deposition annealing at 240 to 300 °C.
Defect Termination of Flash-Lamp-Crystallized Large-Grain Polycrystalline Silicon Films by High-Pressure Water Vapor Annealing
Authors: Ohdaira Keisuke
Published: April 2013

High-pressure water-vapor annealing (HPWVA) is performed on 3-µm-thick polycrystalline silicon (poly-Si) films formed on glass substrates by crystallizing electron-beam (EB)-evaporated precursor amorphous Si (a-Si) films by flash lamp annealing (FLA). HPWVA at higher temperature and pressure tends to result in a lower defect density of FLC poly-Si films. The defect density of FLC poly-Si films can be reduced from ∼3×1017 to ∼2×1016/cm3 when the HPWVA temperature is 500 °C and the pressure is more than 8 MPa, which is sufficiently of device grade. The annealing of flash-lamp-crystallized (FLC) poly-Si films under inert-gas atmosphere does not lead to sufficient reduction in their defect density, indicating the necessity of water vapor during annealing.
Improvement of Photovoltaic Characteristics by MoO3 Doping of Thick Hole-Transporting Films
Authors: Shinmura Yusuke , Kubo Masayuki , Kaji Toshihiko , Hiramoto Masahiro
Published: April 2013

Thick heterojunction cells composed of fullerene and p-type hole-transporting materials (HTMs) doped with molybdenum oxide (MoO3) were fabricated. The Fermi level (E
F) of HTMs shifted toward the positive direction and close to the upper edge of the valence band following MoO3 doping. These E
F shifts indicate that intrinsic HTMs changed to be of the p-type. The introduction of p-type HTMs to the cells increased photocurrent density and fill factor. The increase in photocurrent density can be explained by the formation of built-in potential at the interface between p-type HTMs and C60. On the other hand, the increase in fill factor can be explained by the drastic decrease in the resistance of 300-nm-thick HTM films, which reached a very small value of 2 Ω.
Progress and Prospect of the Growth of Wide-Band-Gap Group III Nitrides: Development of the Growth Method for Single-Crystal Bulk GaN
Authors: Amano Hiroshi
Published: April 2013

Thin films of III–V compound semiconductors such as GaAs and InP can be grown on native substrates, whereas such growth was difficult for group III nitride semiconductors. Despite this drawback, scientists have gradually become able to use the functions of group III nitride semiconductors by growing their thin films on non-native substrates such as sapphire and Si substrates. With the continuously increasing demand for the conservation and generation of energy, bulk substrates of group III nitride semiconductors are highly expected to maximize their potential. In this report, I review the current status of the growth methods for bulk GaN single crystals used for substrates as well as summarize the characteristics of blue light-emitting diodes (LEDs), heterojunction field-effect transistors (HFETs), and photovoltaic cells on GaN substrates.
Formation of Semi-Insulating Layers on Semiconducting β-Ga2O3 Single Crystals by Thermal Oxidation
Authors: Oshima Takayoshi , Kaminaga Kenichi , Mukai Akira , Sasaki Kohei , Masui Takekazu , Kuramata Akito , Yamakoshi Shigenobu , Fujita Shizuo , Ohtomo Akira
Published: April 2013

Semi-insulating layers (SIL) were formed on the surfaces of nominally undoped β-Ga2O3 (010) single crystals by thermal oxidation. Capacitance–voltage measurement with double Schottky configuration was performed to evaluate the increase in the thickness of the SIL as a function of annealing temperature and time. A SiO2 layer prepared on the surface prevented the extension of the SIL, indicating that oxygen incorporation from air and successive bulk diffusion dominated the carrier compensation process. The activation energy of oxygen diffusion coefficient was estimated to be 4.1 eV.
Center Wavelength Adoption Techniques for Supercontinuum Generating Highly Nonlinear Noncircular Core Photonic Crystal Fiber
Authors: Hossain Md. Anwar , Namihira Yoshinori
Published: April 2013

A supercontinuum (SC) light source is designed using a highly nonlinear noncircular core photonic crystal fiber (HNL-NcPCF) with all-normal group velocity dispersion (GVD) to demonstrate how simply an SC can be generated at different center wavelengths in a normal GVD regime. Using the finite element method (FEM) with a perfectly matched layer (PML), the design of two or more PCF-based light sources at different neighboring center wavelengths is demonstrated numerically. Moreover, SC generations are demonstrated numerically at 1.06, 1.31, and 1.55 µm in a normal dispersion regime using picosecond optical pulses.
Size Dependence of Ferromagnetic Resonance Frequency in Submicron Patterned Magnet
Authors: Manago Takashi , Yamanoi Kazuto , Yakata Satoshi , Kimura Takashi
Published: April 2013

We investigated the size effect on ferromagnetic resonance (FMR) in a submicron-wide single permalloy bar. The resonant frequency markedly increased with decreasing bar width to less than 1 µm, since the demagnetizing field is effectively modified by changing the bar width even in thin films. The resonant frequency difference between 100- and 1000-nm-wide bars was over 4 GHz in the absence of a magnetic field. This characteristic is promising for practical microwave devices because the desired resonant frequency can be obtained simply by varying the width of narrow ferromagnetic bars so that it is not necessary to change the material or magnetic field.
Performance Estimation of Silicon-Based Self-Cooling Device
Authors: Fukuda Shinji , Sabi Yuichi , Kawahara Toshio , Yamaguchi Satarou
Published: April 2013

Since self-cooling devices were first proposed, several materials have been tested for their suitability to be used in them. A self-cooling device requires a high Seebeck coefficient, a low electrical resistivity, and a high thermal conductivity. Here, we report experimental results for single-crystal silicon doped with boron. Samples were fabricated with carrier densities in the range of 2.0×1015 to 1.6×1019 cm-3, and their Seebeck coefficient and electrical resistivity were measured. Silicon with a carrier density of 1.6×1019 cm-3 has a power factor of 4.8×10-3 W/(K2·m) at room temperature. The cooling capability of a self-cooling device was estimated using a one-dimensional model. The results suggest that a self-cooling device based on silicon with a high carrier density can have a higher heat removal performance than a conventional silicon power device of the same size.
Particle Size Determining Equation in Metallic Nanopowder Preparation by Pulsed Wire Discharge
Authors: Tokoi Yoshinori , Cho Hong-Baek , Suzuki Tsuneo , Nakayama Tadachika , Suematsu Hisayuki , Niihara Koichi
Published: April 2013

Copper nanopowders are prepared by pulsed wire discharge (PWD) using copper wires in nitrogen gas. From experimental results obtained in the present study and published literature, a relationship to predict the particle size of powders prepared by PWD is proposed. A theoretical plasma/vapor density (D
th), which is the most important factor for controlling the particle size is defined as m
P
E
c
-1, where m, P, and E
c are the weight of the wire, pressure of nitrogen gas, and charged energy in the capacitor, respectively. From high-speed photographs obtained during PWD, the relationship between the measured D
exp and D
th is shown by D
exp∝D
th
0.6. The relationship between the median particle diameter d
50 and D
th is found to be d
50∝D
exp∝(D
th
0.6)0.4 by transmission electron microscopy observations. This empirical relationship is in agreement with that expected from the formation and growth of particles via Brownian coagulation of free molecules. From the above relationship, it is possible to predict and control the particle size of powders prepared by PWD.
GaAs/InGaP Core–Multishell Nanowire-Array-Based Solar Cells
Authors: Nakai Eiji , Yoshimura Masatoshi , Tomioka Katsuhiro , Fukui Takashi
Published: April 2013

Semiconductor nanowires (NWs) are good candidate for light-absorbing material in next generation photovoltaic and III–V NW-based multi-heterojunction solar cells using lattice-mismatched material system are expected as high energy-conversion efficiencies under concentrated light. Here we demonstrate core–shell GaAs NW arrays by using catalyst-free selective-area metal organic vapor phase epitaxy (SA-MOVPE) as a basis for multijunction solar cells. The reflectance of the NW array without any anti-reflection coating showed much lower reflection than that of a planar wafer. Next we then fabricated core–shell GaAs NW array solar cells with radial p–n junction. Despite the low reflectance, the energy-conversion efficiency was 0.71% since a high surface recombination rate of photo-generated carriers and poor ohmic contact between the GaAs and transparent indium–tin-oxide (ITO) electrode. To avoid these degradations, we introduced an InGaP layer and a Ti/ITO electrode. As a result, we obtained a short-circuit current of 12.7 mA cm-2, an open-circuit voltage of 0.5 V, and a fill factor of 0.65 for an overall efficiency of 4.01%.
Characteristics of Electron Conduction in a Gas under a Quadrupole Magnetic Field and Radio-Frequency Electric Fields
Authors: Sugawara Hirotake
Published: April 2013

Electron conduction in CF4under a simplified model quadrupole magnetic field (QMF) and rf electric fields atf= 13.56, 27.12, and 40.68 MHz was analyzed using a Monte Carlo method, following the manner of electron swarm analyses. This field configuration simulated current paths of magnetic neutral loop discharge plasmas used for dry etching. The electron conduction therein was focused on as an elemental process of plasma power deposition. The electrons formed a star-shaped distribution with four rays along the separatrices of the QMF. The effective electron conductivity quantified as the amplitude of mean electron velocity was high around the central axis. The time-averaged mean electron velocities in the four regions of the QMF were biased under a rectification effect of the magnetic field. With increasingf, the high-conductivity region expanded and ionization was promoted. An enhancement of plasma power deposition under high driving frequencies was indicated.
Experiences and Perspectives of Adults Living With Systemic Lupus Erythematosus: Thematic Synthesis of Qualitative Studies
Authors: Sutanto Bernadet , Singh‐Grewal Davinder , McNeil H. Patrick , O'Neill Sean , Craig Jonathan C. , Jones Julie , Tong Allison
Published: April 2013

Objective

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease that significantly impairs patients' quality of life and can be life threatening. This study aimed to describe the experiences and perspectives of adults living with SLE.

Methods

We conducted a systematic review and thematic synthesis of qualitative studies that explored the experiences of adults living with SLE. We searched MEDLINE, Embase, PsycINFO, CINAHL (to November week 1, 2012), Google Scholar, a thesis database, and reference lists of relevant articles.

Results

Forty‐six studies involving 1,385 participants were included. Five themes were identified: restricted lifestyle (including subthemes of pervasive pain, debilitating fatigue, mental deterioration, disruptive episodic symptoms, and postponing parenthood), disrupted identity (gaining diagnostic closure, prognostic uncertainty, being a burden, hopelessness, heightened self‐consciousness, fearing rejection, and guilt and punishment), societal stigma and indifference (illness trivialization, socially ostracized, and averse to differential treatment), gaining resilience (optimism, control and empowerment, being informed and involved, and valuing mutual understanding), and treatment adherence (preserving health, rapport with clinicians, negotiating medication regimens, and financial burden).

Conclusion

SLE has a severe and pervasive impact on patients' self‐esteem and independence. Their physical and social functioning is limited and they feel anxious about their future. Patients perceive that SLE is trivialized, misunderstood, and stigmatized by their family, friends, and physicians, which intensifies their sense of isolation. Educational, psychosocial, and self‐care interventions are needed to promote mental resilience, positive coping strategies, self‐advocacy, and capacities for social participation, and thereby to achieve better treatment and health outcomes in patients with SLE.
The Thermophysical Properties of Liquid TRIP/TWIP‐Steel Alloys Using the Maximum Bubble Pressure Method
Authors: Dubberstein Tobias , Heller Hans‐Peter
Published: April 2013

The thermophysical properties of liquid Cr‐Mn‐Ni steel alloys (16 wt% Cr, 7 wt% Mn, and 3–9 wt% Ni) are investigated using the maximum bubble pressure method in which the manganese evaporation and change in chemical composition is very low after experimental trial. The surface tension of copper was measured as reference and experimental σ is in the range of literature values. It is shown that for AISI 304 austenitic steel the surface tension decreased by an increase of oxygen concentration in steel composition. For Cr‐Ni and Cr‐Mn‐Ni steels, the temperature coefficient is positive which is explained by sulfur steel concentrations larger 50 mass ppm. A slight influence of nickel to the surface tension of Cr‐Mn‐Ni steels was experimentally observed where σ was lowered by rising weight percentage of nickel.
Formation of Functionalized Nanowires by Control of Self‐Assembly Using Multiple Modified Amyloid Peptides
Authors: Sakai Hiroki , Watanabe Ken , Asanomi Yuya , Kobayashi Yumiko , Chuman Yoshiro , Shi Lihong , Masuda Takuya , Wyttenbach Thomas , Bowers Michael T. , Uosaki Kohei , Sakaguchi Kazuyasu
Published: April 2013

Amyloid peptides have great potential as building blocks in the creation of functional nanowires due to their natural ability to self‐assemble into nanofibrillar structures and because they can be easily modified with various functional groups. However, significant modifications of an amyloid peptide generally alter its self‐assembly property, making it difficult to construct functionalized fibrils with a desired structure and function. In this study, a very effective method to overcome this problem is demonstrated by using our structure‐controllable amyloid peptides (SCAPs) terminated with a three‐amino‐acid‐residue cap. The method consists on mixing two or more structurally related amyloid peptides with a fraction of modified SCAPs which co‐assemble into a fibril. This SCAP‐mixing method provides remarkable control over the self‐assembly process both on the small oligomers level and the macroscopic fibrils level. Furthermore, it is shown that the modified peptides imbedded in the resulting fibril can subsequently be functionalized to generate nanowires with the desired properties, highlighting the importance of this SCAP method for nanotechnology applications.
Carbon dioxide‐in‐water foams stabilized with nanoparticles and surfactant acting in synergy
Authors: Worthen Andrew J. , Bryant Steven L. , Huh Chun , Johnston Keith P.
Published: April 2013

Synergistic interactions at the interface of nanoparticles (bare colloidal silica) and surfactant (caprylamidopropyl betaine) led to the generation of viscous and stable CO2‐in‐water (C/W) foams with fine texture at 19.4 MPa and 50°C. Interestingly, neither species generated C/W foams alone. The surfactant became cationic in the presence of CO2 and adsorbed on the hydrophilic silica nanoparticle surfaces resulting in an increase in the carbon dioxide/water/nanoparticle contact angle. The surfactant also adsorbed at the CO2–water interface, reducing interfacial tension to allow formation of finer bubbles. The foams were generated in a beadpack and characterized by apparent viscosity measurements both in the beadpack and in a capillary tube viscometer. In addition, the macroscopic foam stability was observed visually. The foam texture and viscosity were tunable by controlling the aqueous phase composition. Foam stability is discussed in terms of lamella drainage, disjoining pressure, interfacial viscosity, and hole formation. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3490–3501, 2013
Development of the human aortic arch system captured in an interactive three‐dimensional reference model
Authors: Rana M. Sameer , Sizarov Aleksander , Christoffels Vincent M. , Moorman Antoon F.M.
Published: April 2013

Variations and mutations in the human genome, such as 22q11.2 microdeletion, can increase the risk for congenital defects, including aortic arch malformations. Animal models are increasingly expanding our molecular and genetic insights into aortic arch development. However, in order to justify animal‐to‐human extrapolations, a human morphological, and molecular reference model would be of great value, but is currently lacking. Here, we present interactive three‐dimensional reconstructions of the developing human aortic arch system, supplemented with the protein distribution of developmental markers for patterning and growth, including T‐box transcription factor TBX1, a major candidate for the phenotypes found in patients with the 22q11.2 microdeletion. These reconstructions and expression data facilitate unbiased interpretations, and reveal previously unappreciated aspects of human aortic arch development. Based on our reconstructions and on reported congenital anomalies of the pulmonary trunk and tributaries, we postulate that the pulmonary arteries originate from the aortic sac, rather than from the sixth pharyngeal arch arteries. Similar to mouse, TBX1 is expressed in pharyngeal mesenchyme and epithelia. The endothelium of the pharyngeal arch arteries is largely negative for TBX1 and family member TBX2 but expresses neural crest marker AP2α, which gradually decreases with ongoing development of vascular smooth muscle. At early stages, the pharyngeal arch arteries, aortic sac, and the dorsal aortae in particular were largely negative for proliferation marker Ki67, potentially an important parameter during aortic arch system remodeling. Together, our data support current animal‐to‐human extrapolations and future genetic and molecular analyses using animal models of congenital heart disease. © 2013 Wiley Periodicals, Inc.
Novel mutation in TP63 associated with ectrodactyly ectodermal dysplasia and clefting syndrome and T cell lymphopenia
Authors: Giampietro Philip F. , Baker Mei W. , Basehore Monica J. , Jones Julie R. , Seroogy Christine M.
Published: April 2013

A male child with clinical features consistent with EEC/EECUT plus syndrome (ectrodactyly, ectodermal dysplasia, clefting, urinary tract abnormalities, and thymic abnormalities) including mild ectodermal abnormalities, ectrodactyly of hands and feet, cleft palate, bilateral hydronephrosis, and T cell lymphopenia is reported. He was noted to have T cell receptor excision circle (TREC) analysis below the cutoff for normal on newborn screening and T cell lymphopenia on further immunologic evaluation. A novel, presumably pathogenic de novo 3 bp deletion in exon 7 of TP63 (c.970_972delATT; NCBI Reference Sequence NM_003722.4) was identified. This observation provides supporting evidence for the association between TP63 mutations and EECUT plus syndrome. Clinicians caring for infants presenting with EEC spectrum disorders in the newborn period should also consider the possibility of T cell lymphopenia. © 2013 Wiley Periodicals, Inc.
Endocrine Control of Growth
Authors: MURRAY PHILIP G. , CLAYTON PETER E.
Published: April 2013

Human growth is a complex process starting at conception and completing in adolescence at the time of growth plate fusion. Growth can be divided into four phases: (1) fetal, where the predominant endocrine factors controlling growth are insulin and the insulin‐like growth factors. (2) Infancy, where growth is mainly dependent upon nutrition. (3) Childhood, where the growth hormone–insulin‐like growth factor‐I (GH‐IGF‐I) axis and thyroid hormone are most important. (4) Puberty, where along with the GH‐IGF‐I axis the activation of the hypothalamo‐pituitary–gonadal axis to generate sex steroid secretion becomes vital to the completion of growth. GH is released from the pituitary in a pulsatile fashion under the control of GHRH, Ghrelin, and somatostatin and, via a complex signal transduction cascade, initiates the release of IGF‐I within many tissues but predominantly the liver and at the growth plate. IGF‐I acts in an autocrine and paracrine manner via the IGF‐I receptor to stimulate cell proliferation and longitudinal growth. Activation of the pituitary–gonadal axis during puberty occurs via a complex interaction of factors including kisspeptin, leptin, gonadotrophin releasing hormone, and tachykinin ultimately leading to augmentation of GH secretion, the pubertal growth spurt, and fusion of the growth plates. Many other hormones can affect the GH‐IGF‐I system or directly affect cell proliferation at the growth plate including thyroid hormone, vitamin D, and corticosteroids. © 2013 Wiley Periodicals, Inc.