bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Scattering Direction of Hot Electrons in the Drain of Ballistic n+–i–n+ Diode
Authors: Abudukelimu Abudureheman , Yasenjiang Wufuer , Kakushima Kuniyuki , Ahmet Parhat , Geni Mamtimin , Natori Kenji , Iwai Hiroshi
Published: October 2011

Ionized impurity scattering has a weak influence on hot electron transport at low doping concentrations owing to the fact that ionized impurity scattering is an anisotropic scattering with a high preference for forward scattering and most hot electrons are absorbed in the drain after undergoing ionized impurity scattering. On the other hand, ionized impurity scattering approaches isotropic characteristics at sufficiently high doping concentrations and enhances the scattering of hot electrons in the backward direction and severely degrades the peak of the mean velocity of electrons in the channel and the steady-state current. We conclude that the scattering direction is an important factor for hot electron transport in the drain region of semiconductor devices.
Numerical Analysis of Buffer-Trap Effects on Gate Lag in AlGaN/GaN High Electron Mobility Transistors
Authors: Nakajima Atsushi , Fujii Kunitaka , Horio Kazushige
Published: October 2011

Two-dimensional analysis of turn-on characteristics in AlGaN/GaN high electron mobility transistors (HEMTs) is performed by considering a deep donor and a deep acceptor in a buffer layer. Effects of buffer traps on gate lag are studied. It is shown that relatively large gate lag arises due to buffer traps, and it is correlated to large source access resistance in AlGaN/GaN HEMTs. The dependences of buffer-related gate lag on the gate length and buffer-trap parameters such as a deep-acceptor density and a deep donor's energy level are also studied. It is shown that the gate lag becomes smaller for a longer gate length because electron injection into the buffer layer occurs at the drain edge of the gate and normalized trapping effects become smaller. It is also shown that the gate lag becomes more significant when the deep-acceptor density in the buffer layer becomes higher, because the trapping effects become larger. In addition, the gate-lag rate is shown to be not so dependent on the deep-donor's energy level. Effects of surface states on gate lag are also described briefly.
Linear and Femtosecond Optical Nonlinear Properties of Au/Al2O3 Thin Films Prepared by a Sputtering Method
Authors: Tanahashi Ichiro , Mito Akihiro
Published: October 2011

Au nanoparticles embedded in Al2O3 thin films (Au/Al2O3 films) with a high concentration of Au particles (8–28 at. %) were prepared by a multitarget sputtering method. The size of Au nanoparticles was controlled by the deposition time of Au during the sputtering. In the optical absorption spectra of the Au/Al2O3 film with the mean Au particle diameter of 4.2 nm, the absorption peak due to the localized surface plasmon resonance (LSPR) of the Au particles was observed at 557 nm. The real and imaginary parts of the third-order nonlinear susceptibility, textRe [χ(3)] and textIm [χ(3)], of the film measured at 540 nm by the femtosecond Z-scan technique were estimated to be 2.1 ×10-9 and -6.5 ×10-9 esu, respectively. The nonlinear response time derived from the recovery time of the nonlinear absorption was estimated to be 1.7 ps at the absorption peak of the LSPR.
Theoretical Simulation of Deformed Carbon Nanotubes with Adsorbed Metal Atoms: Enhanced Reactivity by Deformation
Authors: Hosoya Naoki , Kusakabe Koichi , Maheswari S. Uma
Published: October 2011

Simulations adopting the generalized gradient approximation in the density functional theory were performed to investigate the reaction of carbon nanotubes with adsorbed metal atoms. Mechanical modification of the structure of carbon nanotubes enhances their chemical reactivity. Adsorption of W, Ta, or Nb on a (5,0) nanotube with a Stone–Wales defect was shown to have characteristically strong chemisorption. Bond-breaking in the C–C network and formation of a local metal–carbon complex were observed during the simulation. The adsorption of W, Ta, Nb, or Mo on a twisted (5,0) nanotube showed a preferred breaking of several bonds, even creating an opening in the wall. The enhanced chemical reactivity of deformed nanotubes is characterized by the formation of a metal–carbon complex. Applications of the reaction are suggested.
Effect of VI/II Gas Ratio on the Epitaxial Growth of ZnO Films by Metalorganic Chemical Vapor Deposition
Authors: Choi Yong-Seok , Hwang Dae-Kue , Kwon Bong-Joon , Kang Jang-Won , Cho Yong-Hoon , Park Seong-Ju
Published: October 2011

We report the effect of the VI/II ratio on the metalorganic chemical vapor deposition (MOCVD) growth of ZnO film. The surface of ZnO film becomes very smooth as the VI/II ratio increases. Atomic force microscopy measurement shows that ZnO films grown at a VI/II ratio of 25,000 have atomically flat terraces with a root-mean-square roughness of 0.2 nm. Low-temperature photoluminescence spectra also reveal a very sharp excitonic emission comprised of a neutral donor bound exciton emission and a free exciton emission with first and second longitudinal optical (LO) phonon replicas, indicating that the ZnO epilayer is of a high optical quality.
Kink-Pair Mechanism in <001> SrTiO3 Single Crystal Compression-Deformed at Room Temperature
Authors: Yang Kai-Hsun , Ho New-Jin , Lu Hong-Yang
Published: October 2011

We have analyzed the microstructure of <001> SrTiO3 single crystal deformed using compression at room temperature using transmission electron microscopy. A representative stress–strain (σ–ε) curve is established, similar to that for metals it consists of three hardening stages before failure occurs at a strain ε= 19±2%. Dislocation analysis suggests that the primary slip systems in [011](011) and [011](011) are activated in the σ–ε curve stress plateau region usually addressed as easy glide. Three characteristic features are identified from samples deformed to stage I hardening by easy glide: (a) rectangular glide loops, (b) collinear partials, and (c) kink pairs. Dislocations have predominantly pure edge character. Kink pairs are observed only on the edge segments suggesting that screw dislocations have higher mobility. In easy glide, the migration and annihilation of kink pairs occurring on both the trailing and leading partials lends support to a previous report by Castillo-Rodríguez and Sigle (2011) that dislocation glide is controlled by the long-segment limit of a kink-pair model.
Characterization of Resistive Switching States in W/Pr0.7Ca0.3MnO3 for a Submicron (φ250 nm) Via-Hole Structure
Authors: Siddik Manzar , Biju Kuyyadi P. , Liu Xinjun , Lee Joonmyoung , Kim Insung , Kim Seonghyun , Lee Wootae , Jung Seungjae , Lee Daeseok , Sadaf Sharif , Hwang Hyunsang
Published: October 2011

Analysis of asymmetric current–voltage (I–V) of low resistance state (LRS) and high resistance state (HRS) in a W/Pr0.7Ca0.3MnO3 (PCMO) submicron (φ250 nm) resistive memory device revealed the formation of a Schottky-like contact in both states. Raman spectroscopy analysis was used to measure the concentration of oxygen vacancies in LRS and HRS. A significant intensity difference at ∼610 cm-1 for HRS and LRS indicates that a higher number of oxygen vacancies are created in HRS than in LRS. Based on material analysis, modulation of the oxygen vacancy concentration at the PCMO layer in relation to the redox reaction between W and Mn proposed to be responsible for resistive switching phenomena.
Electrical Explosion of Silicon Rod in Distilled Water
Authors: Cho Chuhyun , Ha Yoon-Cheol , Kang Chungil , Jin Yun-Sik , Rim Geun-Hie
Published: October 2011

Silicon, a nonmetallic material that cannot be exploded by wire explosion in a gaseous atmosphere, was successfully exploded in distilled water. The explosion features of the Si rod were very similar to those of metal wires. The energies deposited in a single rod were estimated using the current drop and rise points in the discharge waveform, and they found to be in good agreement with the thermodynamic data for the vaporization and ionization energies of silicon, respectively. The particles produced by the explosion have a spherical shape with a range of 20 to 200 nm diameter for nanosized SiO2 powder.
Measurement of DNA Double-Strand Break Yield in Human Cancer Cells by High-Current, Short-Duration Bunches of Laser-Accelerated Protons
Authors: Yogo Akifumi , Sato Katsutoshi , Nishikino Masaharu , Maeda Takuya , Sakaki Hironao , Hori Toshihiko , Ogura Koichi , Nishiuchi Mamiko , Teshima Teruki , Nishimura Hiroaki , Kondo Kiminori , Bolton Paul R. , Kawanishi Shunichi
Published: October 2011

To investigate the radiobiological effects of high dose rates that are attributed to high current, short bunch beam generation with laser-dreven ion acceleration, we have developed an experimental setup that uses laser-accelerated protons.In-vitrohuman lung cancer cells: A549 pulmonary adenocarcinoma are irradiated with a laser-accelerated proton bunches with a duration of 2×10-8s and flux of ∼1015cm-2s-1, amounting to single bunch absorbed dose at the 1 Gy level. The double-strand break (DSB) yield in cell DNA is analyzed for the laser-accelerated proton beam at an average LET of 41 keV/µm.
Flow Analysis of Photoresist Spray Coating towards Improving Coverage on Three-Dimensional Structures
Authors: Kumagai Shinya , Tajima Hisayoshi , Sasaki Minoru
Published: October 2011

Gas flow in photoresist spray coating is numerically analyzed to reveal the flow in the vicinity of a substrate with trench structures. With increasing Reynold's number, gas flows enter the trenches to deeper positions, forming vortexes. Compared with experimental results, it is shown that bump formations, which are frequently observed around the convex corner of the trench sidewall, are related to the position of the boundary between the flow ejected from the spray nozzle and the vortexes confined inside the trenches. Moving laterally away from the center axis of the nozzle, the lateral flow along the substrate surface becomes dominant in the vicinity of the substrate and, consequently, photoresist particles tend to deposit on top of the trenches.
Magnetization Reversal in Different Magnetic Thin Films Studied Using a Magnetic Actuator
Authors: Hsieh Yi-Ping , Wei Zung-Hang , Yip Ming-Chuen
Published: October 2011

We propose a novel method for observing the magnetization reversal of ferromagnetic thin film; the novel method is to observe the deflection of a magnetic actuator under various magnetic fields. However, they are necessary that the magnetic actuator is bent using a ferromagnetic thin film and that the deflection of the magnetic actuator is obvious enough to study the magnetization reversal of the ferromagnetic thin film. The magnetic actuator consisting of a 76×0.75×0.3 µm3 silicon oxide microcantilever and a 75×9×0.3 µm3 silicon oxide plate deposited on a ferromagnetic multilayer thin film is successfully fabricated using electron beam lithography and electron beam evaporation, and placed in various magnetic fields to observe its flexure. In this study, three shapes of magnetic element are designed: 60×1×0.09 µm3, 60×3×0.09 µm3, and 60×6×0.09 µm3. In the sweep-down process, the magnetization of the 60×6×0.09 µm3 ferromagnetic thin film is reversed at -147 G; the magnetization of the 60×3×0.09 µm3 ferromagnetic thin film is reversed at -313 G; and the magnetization of the 60×6×0.09 µm3 ferromagnetic thin film is reversed at -643 G. The study is useful for applications of the magnetic actuator.
Development of a Frequency-Domain Method Using Completely Optical Techniques for Measuring the Interfacial Thermal Resistance between the Metal Film and the Substrate
Authors: Kato Ryozo , Xu Yibin , Goto Masahiro
Published: October 2011

In this paper, we describe the development of a new frequency-domain (FD) method using completely optical techniques for determining the interfacial thermal resistance between a metal film and its substrate. The 3ω method, which is a FD method based on the technique of photolithography to define a metal-film heater/thermometer pattern, has been most widely used so far. The 2ω method implemented a thermoreflectance technique for measuring ac temperature. In this study we additionally implement a laser technique for periodic heating. Our new method can provide the absolute value of interfacial thermal resistance between a film and its substrate, using the known thermophysical properties of the substrate material, even though the optical power of the pump laser and the optical properties of the metal film are unknown. To verify the method, we measure the thermal resistance of interfaces such as, Au–Al2O3, Bi–Al2O3, Au–SiO2 (thermally oxidized), and Bi–SiO2 (thermally oxidized). The results of the measurements show good agreement with the data obtained by the 2ω method and with the data theoretically predicted using the diffusion mismatch model (DMM).
Large-Scale Test Circuits for High-Speed and Highly Accurate Evaluation of Variability and Noise in Metal–Oxide–Semiconductor Field-Effect Transistor Electrical Characteristics
Authors: Kumagai Yuki , Abe Kenichi , Fujisawa Takafumi , Watabe Shunichi , Kuroda Rihito , Miyamoto Naoto , Suwa Tomoyuki , Teramoto Akinobu , Sugawa Shigetoshi , Ohmi Tadahiro
Published: October 2011

To develop a new process technology for suppressing the variability and noise in metal–oxide–semiconductor field-effect transistors (MOSFETs) for large-scale integrated circuits, accurate and rapid measurement test circuits for the evaluation of a large number of MOSFET electrical characteristics were developed. These test circuits contain current-to-voltage conversion circuits and simple scanning circuits in order to achieve rapid and accurate evaluation for a wide range of measurement currents. The test circuits were fabricated and the variabilities and noises in drain–source current, gate leakage current, and p–n junction leakage current were evaluated using a large-scale test circuit.
Effect of In2O3 Underlayer on Crystallinity of Hexagonal InN and InGaN Thin Films Grown on c-Face Sapphire Substrates
Authors: Sato Yuichi , Ito Kazuki
Published: October 2011

In2O3 thin films were applied as underlayers for the growth of hexagonal InN and InGaN thin films on sapphire c-face substrates. Crystallinities of the nitride thin films grown with and without the In2O3 underlayer were compared, and the effect of the underlayer on these crystallinities was investigated. The application of (111)-faced heteroepitaxial In2O3 underlayers brought clear improvement effects on the crystallinities. In2O3 can be added to one of the promising underlayer materials for the hexagonal nitride thin film growth on the c-face sapphire substrate in addition to the typical nitride buffer layer materials, such as GaN and AlN.
Rare Earth Oxide Capping Effect on La2O3 Gate Dielectrics for Equivalent Oxide Thickness Scaling toward 0.5 nm
Authors: Kouda Miyuki , Kakushima Kuniyuki , Ahmet Parhat , Tsutsui Kazuo , Nishiyama Akira , Sugii Nobuyuki , Natori Kenji , Hattori Takeo , Iwai Hiroshi
Published: October 2011

The capping La2O3 gate dielectric with rare earth oxide (Ce, Pr, Nd, and Tm oxides) and the influence of rare earth oxides on the interface reaction have been examined and the electrical characteristics have been evaluated. The formation of Si-rich silicate phase in the interfacial silicate layer have been suppressed with Nd and Tm oxide cappings, presumably owing to the reduced generation rate of radical oxygen atoms in the cappings. Therefore, Nd and Tm oxide capping has advantage in scaling the equivalent oxide thickness owing to the increase in the average dielectric constant with reduced leakage current. On the other hand, Ce- and Pr-oxide cappings have shown no appreciable influence on the interfacial reaction to that without capping. However, with Ce-oxide capping, positively charged fixed defects created in smaller equivalent oxide thickness (EOT) can be well suppressed owing to the valence number fluctuation properties. Although capacitors and transistors with the rare earth cappings have shown the same degradation tendency along with the equivalent oxide thickness, Nd or Tm capping is one of the promising candidates for scaling device with La2O3.
Silicate Reaction Control at Lanthanum Oxide and Silicon Interface for Equivalent Oxide Thickness of 0.5 nm: Adjustment of Amount of Residual Oxygen Atoms in Metal Layer
Authors: Kitayama Daisuke , Kubota Toru , Koyanagi Tomotsune , Kakushima Kuniyuki , Ahmet Parhat , Tsutsui Kazuo , Nishiyama Akira , Sugii Nobuyuki , Natori Kenji , Hattori Takeo , Iwai Hiroshi
Published: October 2011

A guideline to select appropriate gate electrode materials to achieve an equivalent oxide thickness (EOT) of 0.5 nm with La2O3 gate dielectric has been proposed. The key parameter includes the adjustment of the amount of supplied oxygen atoms, which trigger the formation of the silicate layer at the interface, by selecting a metal with moderate free energy of oxygen. In addition, the thickness of the metal gate has been found to play an important role in silicate formation. Based on this guideline, an EOT of 0.5 nm with 3.5 nm La2O3 and 6 nm W gate electrode annealed at 800 °C was achieved. The hysteresis and humps in the capacitance voltage characteristics have been explained by the defect energy levels in the formed silicates and located at the interface with La2O3. The flat-band voltage shift correlated with the thickness of the oxygen-containing metal indicates the existence of fixed charges induced by the gate electrode metal. Finally, an appropriate transistor operation at an EOT of 0.5 nm has been confirmed.
Impact of Nitrogen Incorporation on Low-Frequency Noise of Polycrystalline Silicon/TiN/HfO2/SiO2 Gate-Stack Metal–Oxide–Semiconductor Field-Effect Transistors
Authors: Matsuki Takeo , Hettiarachchi Ranga , Feng Wei , Shiraishi Kenji , Yamada Keisaku , Ohmori Kenji
Published: October 2011

The impact of nitrogen incorporation into HfO2/SiO2 gate dielectrics in the gate-stack fabrication process on the low-frequency noise of the drain current of polycrystalline silicon (poly-Si)/TiN (10 nm)/HfO2/SiO2 gate-stack metal–oxide–semiconductor field-effect transistors (MOSFETs) is studied, considering the scaling of an equivalent oxide thickness with the reduction in interfacial layer SiO2 thickness and the plasma nitriding of gate dielectrics. The nitriding combined with nitrogen plasma and nitrogen diffusion from a 10-nm-thick TiN layer increases the normalized noise power spectral density owing to carrier mobility fluctuation, and decreases the slope γ of the 1/f
γ noise spectrum owing to the increase in the number of trapped carriers at the bulk trap site in the gate dielectric layer. The reduction in SiO2 thickness from 1.5 to 0.8 nm showed less impact on the mentioned phenomena with TiN. These results suggest that nitrogen incorporation into HfO2/SiO2 gate dielectrics in the device fabrication process for poly-Si/metal nitride/HfO2/SiO2 gate stacks requires careful attention to suppress the power density of low-frequency noise.
Behavior of Low-Frequency Noise in n-Channel Metal–Oxide–Semiconductor Field-Effect Transistors for Different Impurity Concentrations
Authors: Hettiarachchi Ranga , Matsuki Takeo , Feng Wei , Yamada Keisaku , Ohmori Kenji
Published: October 2011

In this study, we investigated the behavior of the low-frequency noise of n-channel metal–oxide–semiconductor field-effect transistors as a function of gate overdrive from the viewpoints of subthreshold slope and normalized transconductance. We prepared devices with different uniformities of channel impurity, carrier mobility, and the degree of the short-channel effect by halo implantation and changing the substrate impurity concentration and gate length. It was found that the small subthreshold swing value increases the slope of noise intensity in the subthreshold regime, probably resulting from random nature of the diffusion transport. On the other hand, the magnitude of noise intensity in the strong inversion regime is related to the normalized transconductance, where a small number of scattering events in the channel realize low noise intensity.
Highly Reliable Radical SiO2Films on Atomically Flat Silicon Surface Formed by Low Temperature Pure Ar Annealing
Authors: Li Xiang , Kuroda Rihito , Suwa Tomoyuki , Teramoto Akinobu , Sugawa Shigetoshi , Ohmi Tadahiro
Published: October 2011

The gate oxide films are formed by the microwave exited high density plasma on Si(100) surfaces of various flatness to discuss the reliabilities. By annealing in ultra pure Ar ambient below 900 °C at atmosphere pressure, the whole surface of 200-mm-diameter (100) orientation silicon wafers can be atomically flattened without slip-line defects generation. For the capacitors, the intrinsic life time in charge-to-breakdown (Qbd) characteristics and the breakdown field (Ebd) of radical oxide films are much larger than those of thermal oxide films, and the extrinsicQbdof radical oxide film is drastically improved by forming on atomically flat silicon surface composed with that on conventional Czochralski (Cz)-wafer surface. Moreover, fabricating radical oxide films on the atomically flat wafers, flattened at 800 or 1100 °C in Ar ambient, the equivalent gate oxide breakdown characteristics are obtained.
p-Type Tunneling Field-Effect Transistors on (100)- and (110)-Oriented Si Substrates
Authors: Lee Min Hung , Hsieh Bin-Fong , Wu Tong-Han , Chang Shu Tong
Published: October 2011

p-Type tunneling field-effect transistors (TFETs) on (100)- and (110)-oriented Si substrates were fabricated, and their electrical characteristics were studied. High-k dielectric and metal gate were integrated as a gate stack, and the gate-last process was performed to obtain a high-quality dielectric layer and prevent crystallization. The orientation effect of p-type TFETs on (100) and (110) Si wafers is a high I
ON in the case of the (110) orientation as compared with that of the (100) p-type TFET, which is a high band-to-band tunneling current. The junction profile and effective mass were discussed to determine possible reasons for the orientation effect of p-type TFETs on (100) and (110) Si wafers.
Impact of Cation Surface Termination on the Electrical Characteristics of HfO2/InGaAs(001) Metal–Oxide–Semiconductor Capacitors
Authors: Ohtake Akihiro , Miyata Noriyuki , Urabe Yuji , Yasuda Tetsuji
Published: October 2011

Electrical characteristics of HfO2/InGaAs metal–oxide–semiconductor (MOS) capacitors fabricated on In0.53Ga0.47As(001) surfaces with various surface reconstructions were investigated. To explore the effect of interface structure on the MOS properties, we prepared atomically-controlled Ga-, In-, and Al-rich (4×2) and As-rich (2×4) surfaces on InGaAs(001), and identified their atomic structures. The MOS capacitors fabricated on cation-rich InGaAs surfaces show a smaller capacitance–voltage frequency dispersion, suggesting that the cation-oxide-rich HfO2/InGaAs interfaces is preferable for suppressing interface-state density in the upper half band gap. It was also found that the interface containing higher-atomic-number cation has smaller frequency dispersion. We discuss the origin for the electrical improvement by the cation adsorption.
Capacitance–Voltage Characterization of La2O3 Metal–Oxide–Semiconductor Structures on In0.53Ga0.47As Substrate with Different Surface Treatment Methods
Authors: Zade Dariush , Kanda Takashi , Yamashita Koji , Kakushima Kuniyuki , Nohira Hiroshi , Ahmet Parhat , Tsutsui Kazuo , Nishiyama Akira , Sugii Nobuyuki , Natori Kenji , Hattori Takeo , Iwai Hiroshi
Published: October 2011

We studied InGaAs surface treatment using hexamethyldisilazane (HMDS) vapor or (NH4)2S solution after initial oxide removal by hydrofluoric acid. The effect of each treatment on interface properties of La2O3/In0.53Ga0.47As metal–oxide–semiconductor (MOS) capacitor was evaluated. We found that HMDS surface treatment of InGaAs, followed by La2O3 deposition and forming gas annealing reduces the MOS capacitor's interface state density more effectively than (NH4)2S treatment. The comparison of the capacitance–voltage data shows that the HMDS-treated sample reaches a maximum accumulation capacitance of 2.3 µF/cm2 at 1 MHz with roughly 40% less frequency dispersion near accumulation, than the sample treated with (NH4)2S solution. These results suggest that process optimization of HMDS application could lead to further improvement of InGaAs MOS interface, thereby making it a potential routine step for InGaAs surface passivation.
Control of Interfacial Properties of Al2O3/Ge Gate Stack Structure Using Radical Nitridation Technique
Authors: Kato Kimihiko , Kyogoku Shinya , Sakashita Mitsuo , Takeuchi Wakana , Kondo Hiroki , Takeuchi Shotaro , Nakatsuka Osamu , Zaima Shigeaki
Published: October 2011

We have investigated the control of the interfacial properties of Al2O3/Ge gate stack structures by the radical nitridation technique. In the Al2O3/Ge structures formed by the atomic layer deposition method, the interface state density increases with the deposition temperature due to the decrease in the thickness of the Ge oxide interlayer. On the other hand, the hysteresis width of the capacitance–voltage (C–V) characteristics decreases with increasing deposition temperature, which indicates a decrease in the oxide trap density near the interface. We also investigated the control of the interfacial structure by the radical nitridation of Al2O3/Ge to form an interfacial structure after the deposition of a high-k dielectric layer. The results of X-ray photoelectron spectroscopy reveal that an Al2O3/Ge3N4/GeO2/Ge stack structure is formed after the radical nitridation owing to the minimal oxygen diffusion into the Al2O3/Ge interface. Furthermore, the interfacial mixing is suppressed after radical nitridation at less than 300 °C. As a result, we can decrease the interface state density of the Al2O3/Ge sample after the radical nitridation by more than one order of magnitude compared with that without radical nitridation.
Synchrotron Radiation Photoemission Study of Ge3N4/Ge Structures Formed by Plasma Nitridation
Authors: Hosoi Takuji , Kutsuki Katsuhiro , Okamoto Gaku , Yoshigoe Akitaka , Teraoka Yuden , Shimura Takayoshi , Watanabe Heiji
Published: October 2011

Chemical bonding states and energy band alignment of pure germanium nitride (Ge3N4) layers formed on Ge(100) surfaces by high-density plasma nitridation were characterized by synchrotron radiation photoemission spectroscopy (SR-PES). The core-level shift of 2.31 eV originating from Ge–N bonds (Ge4+) with respect to the bulk Ge 3d5/2 peak position (Ge0+) was determined by peak deconvolution of Ge 3d core-level spectra. In situ SR-PES study on changes in Ge 3d, N 1s, and O 1s core-level spectra during thermal annealing under ultrahigh vacuum (UHV) conditions revealed that oxidized surface layer on Ge3N4 film could be selectively removed at around 500 °C, which was 50 °C lower than the decomposition temperature of Ge3N4. Ge3+ component was found to increase with decreasing Ge4+ component during thermal decomposition of Ge3N4 while no significant change in Ge1+ and Ge2+ components. The Ge3N4 energy bandgap of 3.68 eV was experimentally determined from energy loss spectra of N 1s photoelectrons. The valence band offset at Ge3N4/Ge(100) interfaces were also estimated to be 1.65 eV from valence band spectra, and thus, the energy band alignment between Ge3N4 dielectrics and Ge substrate was determined.
Electric Dipole at High-k/SiO2 Interface and Physical Origin by Dielectric Contact Induced Gap States
Authors: Wang Xiaolei , Han Kai , Wang Wenwu , Ma Xueli , Xiang Jinjuan , Chen Dapeng , Zhang Jing
Published: October 2011

The characteristic of electric dipole at high-k/SiO2 interface is quantitatively analyzed. The dipoles of HfO2/SiO2 and HfGdO
x
/SiO2 systems are experimentally estimated to be about -0.38 and -1.03 V, respectively. The dipole formation is explained by the dielectric contact induced gap states (DCIGS). The charge neutrality level (CNL) of the DCIGS is for the first time utilized to study the dipole moment. The charge transfer due to different CNLs of high-k and SiO2 is considered to be the dominant origin of dipole formation. The prediction by this model is in good agreement with the experimental data.
Semi-Analytical Depletion Width Evaluated by Self-Consistent Schrödinger–Poisson Pair Calculations
Authors: Chung Che-Sheng
Published: October 2011

A self-consistent calculation establishes a bulk built-in potential by applying a DC bias to a gate/insulators/semiconductor (GIS) structure of a metal–oxide–semiconductor field-effect transistor (MOSFET). The width of a semi-analytical depletion layer near the interface of the GIS structure of an n-type MOSFET (nMOSFET) can be extracted by self-consistent calculation. The grand canonical ensemble improves the quantitative calculation for the theoretical evaluation of the self-consistent calculation. It is possible that a new approximation establishing the self-consistent potential appropriately merges with a classical transport model at low temperatures because of minimizing quantum calculations in a momentum space.
pH Sensing Characterization of Programmable Sm2O3/Si3N4/SiO2/Si Electrolyte–Insulator–Semiconductor Sensor with Rapid Thermal Annealing
Authors: Wang Jer-Chyi , Lu Tseng-Fu , Shih Hui-Yu , Yang Chia-Ming , Lai Chao-Sung , Kao Chyuan-Haur , Pan Tung-Ming
Published: October 2011

A programmable silicon–oxide–nitride–oxide–silicon (SONOS)-like electrolyte–insulator–semiconductor (EIS) sensor with a Sm2O3/Si3N4/SiO2/Si structure is demonstrated for pH detection. This proposed programmable EIS sensor with insulator–nitride–oxide (INO) multiple sensing layers exhibits a high pH sensitivity (larger than the ideal Nernst response, ∼59 mV/pH) owing to the hydrogen ion attraction by electrons trapped within the embedded Si3N4 layer after stressing. To increase the pH response, rapid thermal annealing is performed on the programmable EIS devices. The obtained results support our hypothesis that the pH response can be effectively increased after 700 °C annealing. A sensing model on the basis of the charge attraction and surface roughness is also presented. Compared with the conventional EIS device, the programmable EIS sensor functionalized with annealing and stressing can be used in future pH sensor applications owing to its high pH sensing response.
Relationship between Dipole Moment of Organic Compound Impurity in Liquid Crystal Field and Leakage Current of Liquid Crystal Cell
Authors: Kaneko Ikue , Tachibana Kazuhiro , Nishina Tatsuo , Yonetake Koichiro , Ohba Yoshihiro
Published: October 2011

The degradation of the reliability of liquid crystal display (LCD) is dependent on ions in the liquid crystal (LC) cell. However, we found that the nonionic organic compounds added into the LC material also decreased the reliability of LCD because of the leakage current. The conductivity and the dielectric constant of the LC cells containing an LC mixture (ZLI-2293) with or without the nonionic organic compounds were examined by the AC impedance method. The leakage current, as well as the conductivity, was found to be related to the dipole moment of the compound. Therefore, if the dipole moment of the compound is larger than 4 D, the current will tend to leak in the LC cell.
High Pressure Oxidation of 4H-SiC in Nitric Acid Vapor
Authors: Selvi K. Kalai , Sreenidhi Turuvekere , DasGupta Nandita , Ryssel Heiner , Bauer Anton
Published: October 2011

High pressure chemical vapor oxidation of SiC in nitric acid vapor is reported. Higher growth rate at temperatures as low as 400 to 500 °C has been achieved. The oxidation kinetics has been studied. It has been observed that the growth rate is strongly dependent on temperature, and the thickness of the oxide increases almost linearly with time within the error limits. X-ray photoelectron spectroscopy (XPS) measurement has been carried out to study the composition of the oxide. Room temperature electrical characterization (current–voltage and capacitance–voltage) has been carried out to estimate the oxide breakdown field strength, oxide charges, and interface state density. It is observed that prolonged oxidation or oxidation at higher temperature in acid ambient deteriorates the quality of oxide.
High-κ Al2O3/WOx Bilayer Dielectrics for Low-Power Resistive Switching Memory Applications
Authors: Banerjee Writam , Rahaman Sheikh Ziaur , Prakash Amit , Maikap Siddheswar
Published: October 2011

A bipolar resistive switching memory device using high-κ Al2O3/WO
x
bilayer dielectrics in an IrO
x
/Al2O3/WO
x
/W structure with a small device area of 8 ×8 µm2 is investigated for the first time. A high hole trapping density of ∼1.76 ×1018 cm-3 in a high-κ Al2O3 film with a thickness of 5 nm is investigated using IrO
x
/Al2O3/SiO2/p-Si capacitors. The thickness and chemical bonding of the high-κ Al2O3/WO
x
films in a resistive memory device are investigated by both high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The resistive switching memory device with a low power operation of 0.7 mW and a low current compliance of 500 µA has a reasonable SET/RESET voltage of -1.4 V/+1.0 V, a high resistance ratio of >103, an excellent read endurance of >105 times at a large read voltage of -0.5 V, and 10 years of data retention at 85 °C.
The Field Confinement, Narrow Transmission Resonances, and Green Function of a Multilayered Microsphere with Metamaterial Defects
Authors: Burlak Gennadiy , Díaz-de-Anda A.
Published: October 2011

We numerically investigate the optical transmission through a compound spherical stack with
conventional and metamaterial (MM) layers and also embedded MM defect. A formation of extremely narrow resonant peak with nearly complete transmittance in area of a band gap is found.
We demonstrate that photon fields of certain frequencies can be strongly confined by a left-handed
(LH) defect. The influence of a random deviation in the width of compound spherical layers as
well the transit to the whispering gallery mode (WGM) is also discussed.
Reduction of Neighborhood‐Based Generalized Rough Sets
Authors: Wang Zhaohao , Shu Lan , Ding Xiuyong
Published: October 2011

Rough set theory is a powerful tool for dealing with uncertainty, granularity, and incompleteness of knowledge in information systems. This paper discusses five types of existing neighborhood‐based generalized rough sets. The concepts of minimal neighborhood description and maximal neighborhood description of an element are defined, and by means of the two concepts, the properties and structures of the third and the fourth types of neighborhood‐based rough sets are deeply explored. Furthermore, we systematically study the covering reduction of the third and the fourth types of
neighborhood‐based rough sets in terms of the two concepts. Finally, two open problems proposed by Yun et al. (2011) are solved.
Effects of β2 Agonists, Corticosteroids, and Novel Therapies on Rhinovirus-Induced Cytokine Release and Rhinovirus Replication in Primary Airway Fibroblasts
Authors: Van Ly David , King Nicholas J.C. , Moir Lyn M. , Burgess Janette K. , Black Judith L. , Oliver Brian G.
Published: October 2011

Rhinovirus-(RV-) induced asthma exacerbations account for high asthma-related health costs and morbidity in Australia. The cellular mechanism underlying this pathology is likely the result of RV-induced nuclear-factor-kappa-B-(NF-κB-) dependent inflammation. NF-κB may also be important in RV replication as inhibition of NF-κB inhibits replication of other viruses such as human immunodeficiency virus and cytomegalovirus. To establish the role of NF-κB inhibitors in RV-induced IL- 6 and IL-8 and RV replication, we used pharmacological inhibitors of NF-κB, and steroids and/or β2 agonists were used for comparison. Primary human lung fibroblasts were infected with RV-16 in the presence of NF-κB inhibitors: BAY-117085 and dimethyl fumarate; β2 agonist: salmeterol; and/or corticosteroids: dexamethasone; fluticasone. RV-induced IL-6 and IL-8 and RV replication were assessed using ELISAs and virus titration assays. RV replicated and increased IL-6 and IL-8 release. Salmeterol increased, while dexamethasone and fluticasone decreased RV-induced IL-6 and IL-8 (P<0.05). The NF-κB inhibitor BAY-117085 inhibited only RV-induced IL-6 (P<0.05) and dimethyl fumarate did not alter RV-induced IL-6 and IL-8. Dimethylfumarate increased RV replication whilst other drugs did not alter RV replication. These data suggest that inhibition of NF-κB alone is unlikely to be an effective treatment compared to current asthma therapeutics.
Upregulated Expression of Indoleamine 2, 3-Dioxygenase in Primary Breast Cancer Correlates with Increase of Infiltrated Regulatory T CellsIn Situand Lymph Node Metastasis
Authors: Yu Jinpu , Sun Jingyan , Wang Shizhen Emily , Li Hui , Cao Shui , Cong Yizi , Liu Juntian , Ren Xiubao
Published: October 2011

IDO has been reported to induce immunotolerance and promote metastasis in solid malignancy, but the mechanisms involved were not fully understood. In this study, the expression of IDO in primary breast cancer was examined and the correlation between the expression levels of IDO and the densities of Foxp3+Tregsin situwas studied. The IDO stably-expressing CHO cells(IDO/CHO) were generated to evaluate the induction of Foxp3+Tregs after coculturing with CD3+T cellsin vitro. The IDO expression in cancer was higher than that in benign diseases both at RNA and protein levels. The IDO expression was significantly upregulated in tumors of more advanced stages and with more extensive lymph node metastasis, and displayed positive linear correlation with the density of Foxp3+Tregs. We further demonstrated that CD4+CD25+CD127−Tregs could be amplified by coculturing CD3+T cells with IDO/CHO cellsin vitrowhich displayed increasing Foxp3 expression both at mRNA and protein levels. Our results implied that up-regulation of IDO in primary breast cancer may inhibit local immune surveillance and promote metastasis by favoring development and infiltration of Foxp3+Tregs in the tumor microenvironment.
Long-Term Results of Radiofrequency Energy Delivery for the Treatment of GERD: Results of a Prospective 48-Month Study
Authors: Dughera Luca , Navino Monica , Cassolino Paola , De Cento Mariella , Cacciotella Luca , Cisarò Fabio , Chiaverina Michele
Published: October 2011

Since 2000, radiofrequency (RF) energy treatment has been increasingly offered as an alternative option to invasive surgical procedures for selected patients with gastroesophageal reflux disease (GERD). Out of 69 patients treated since June 2002 to December 2007 with the Stretta procedure, 56 of them reached by the end of 2010 a 48-month followup. RF treatment significantly improved heartburn scores, GERD-specific quality of life scores, and general quality of life scores at 24 and 48 months in 52 out of 56 patients (92,8%). At each control time both mean heartburn and GERD HRQL scores decreased ( = 0.001 and = 0.003, resp.) and both mental SF-36 and physical SF-36 ameliorated ( = 0.001 and 0.05, resp.). At 48 months, 41 out of 56 patients (72,3%) were completely off PPIs. Morbidity was minimal, with only one relevant but transient complication. According to other literature data, this study shows that RF delivery to LES is safe and durably improves symptoms and quality of life in well-selected GERD patients.
Successful Handling of Disseminated BCG Disease in a Child with Severe Combined Immunodeficiency
Authors: Bacalhau Sílvia , Freitas Cristina , Valente Rosalina , Barata Deolinda , Neves Conceição , Schäfer Katrin , Lubatschofski Annelie , Schulz Ansgar , Neves João Farela
Published: October 2011

In high-burden countries,Mycobacterium bovisBacillus Calmette-Guérin (BCG) vaccine is administered in newborn to prevent severeMycobacterium tuberculosisinfection. Because life-threatening disseminated BCG disease may occur in children with primary immunodeficiency, vaccination strategy against tuberculosis should be redefined in non-high-burden countries. We report the case of a patient with X-linked severe combined immunodeficiency (SCID) who developed disseminated BCG disease, highlighting the specific strategies adopted.
Regulatory Multidimensionality of Gas Vesicle Biogenesis inHalobacterium salinarumNRC-1
Authors: Yao Andrew I. , Facciotti Marc T.
Published: October 2011

It is becoming clear that the regulation of gas vesicle biogenesis inHalobacterium salinarumNRC-1 is multifaceted and appears to integrate environmental and metabolic cues at both the transcriptional and posttranscriptional levels. The mechanistic details underlying this process, however, remain unclear. In this manuscript, we quantify the contribution of light scattering made by both intracellular and released gas vesicles isolated fromHalobacterium salinarumNRC-1, demonstrating that each form can lead to distinct features in growth curves determined by optical density measured at 600 nm (OD600). In the course of the study, we also demonstrate the sensitivity of gas vesicle accumulation inHalobacterium salinarumNRC-1 on small differences in growth conditions and reevaluate published works in the context of our results to present a hypothesis regarding the roles of the general transcription factor tbpD and the TCA cycle enzyme aconitase on the regulation of gas vesicle biogenesis.
Unusual Giant Right Atrium in Rheumatic Mitral Stenosis and Tricuspid Insufficiency
Authors: Anzouan-Kacou Jean Baptiste , Konin Christophe , Coulibaly Iklo , N'guetta Roland , Adoubi Anicet , Soya Esaïe , Boka Bénédicte
Published: October 2011

Dilation and hypertrophy of the atria occur in patients with valvular heart disease especially in mitral regurgitation, mitral stenosis or tricuspid abnormalities. In sub-saharan Africa, rheumatic fever is still the leading cause of valvular heart disease. We report a case of an unusual giant right atrium in context of rheumatic stenosis and severe tricuspid regurgitation in a 58-year-old woman.
Study on Ductility of Ti Aluminide Using Artificial Neural Network
Authors: Gupta R. K. , Mehta Rama , Agarwala Vijaya , Pant Bhanu , Sinha P. P.
Published: October 2011

Improvement of ductility at room temperature has been a major concern on processing and application of Ti aluminides over the years. Modifications in alloy chemistry of binary alloy (Ti48 Al) and processing conditions were suggested through experimental studies with limited success. Using the reported data, the present paper aims to optimize the experimental conditions through computational modeling using artificial neural network (ANN). Ductility database were prepared, and three parameters, namely, alloy type, grain size, and heat treatment cycle were selected for modeling. Additionally, ductility data were generated from the literature for training and validation of models on the basis of linearity and considering the primary effect of these three parameters. Model was trained and tested for three different datasets drawn from the generated data. Possibility of improving ductility by more than 5% is observed for multicomponent alloy with grain size of 10–50 μm following a multistep heat treatment cycle.
Endogenous Murine Leukemia Viruses: Relationship to XMRV and Related Sequences Detected in Human DNA Samples
Authors: Cingöz Oya , Coffin John M.
Published: October 2011

Xenotropic-murine-leukemia-virus-related virus (XMRV) was the first gammaretrovirus to be reported in humans. The sequence similarity between XMRV and murine leukemia viruses (MLVs) was consistent with an origin of XMRV from one or more MLVs present as endogenous proviruses in mouse genomes. Here, we review the relationship of the human and mouse virus isolates and discuss the potential complications associated with the detection of MLV-like sequences from clinical samples.
Cervicovaginal Safety of the Formulated, Biguanide‐Based Human Immunodeficiency Virus Type 1 (HIV‐1) Inhibitor NB325 in a Murine Model
Authors: Lozenski Karissa , Kish-Catalone Tina , Pirrone Vanessa , Rando Robert F. , Labib Mohamed , Wigdahl Brian , Krebs Fred C.
Published: October 2011

Vaginal microbicides that reduce or eliminate the risk of HIV‐1 sexual transmission must do so safely without adversely affecting the integrity of the cervicovaginal epithelium. The present studies were performed to assess the safety of the biguanide‐based antiviral compound NB325 in a formulation suitable for topical application. Experiments were performed using a mouse model of cervicovaginal microbicide application, which was previously shown to be predictive of topical agent toxicity revealed in microbicide clinical trials. Mice were exposed vaginally to unformulated NB325 or NB325 formulated in the hydroxyethyl cellulose “universal placebo.” Following exposures to formulated 1% NB325 for 10 min to 24 h, the vaginal and cervical epithelia were generally intact, although some areas of minimal vaginal epithelial damage were noted. Although formulated NB325 appeared generally safe for application in these studies, the low but observable level of toxicity suggests the need for improvements in the compound and/or formulation.
Comparing the Mini-BESTest with the Berg Balance Scale to Evaluate Balance Disorders in Parkinson's Disease
Authors: King Laurie A. , Priest Kelsey C. , Salarian Arash , Pierce Don , Horak Fay B.
Published: October 2011

Objective. The purpose of this study was to explore the usefulness of the Mini-BESTest compared to the Berg Balance Scale in evaluating balance in people with PD of varying severity. We evaluated (1) the distribution of patients scores to look for ceiling effects, (2) concurrent validity with severity of disease, and (3) the sensitivity/specificity of separating people with or without postural response deficits.Subjects. Ninety-seven people with PD were tested for balance deficits using the Berg, Mini-BESTest, Unified Parkinson’s Disease Rating Scale (UPDRS) III and the Hoehn & Yahr (H&Y) disease severity classification.Setting. Clinical research facility at Oregon Health & Science University.Results. The Mini-BESTest is highly correlated with the Berg (r=0.79,P<0.001), but avoids the ceiling compression effect of the Berg for mild PD (skewness −2.30 Berg, −0.93 Mini-BESTest). Consequently, the Mini-BESTest is more effective than the Berg for predicting UPDRS Motor score (P<0.001Mini-BESTest versusP=0.86Berg), and for discriminating between those with and without postural response deficits as measured by the H&Y (ROC differentialP=0.06).Conclusion. The Mini-BESTest is a promising tool for discerning balance deficits in patients with PD, most importantly those with more subtle deficits.
Porous Diatomite‐Immobilized Cu–Ni Bimetallic Nanocatalysts for Direct Synthesis of Dimethyl Carbonate
Authors: Chen Yong , Xiao Min , Wang Shuanjin , Han Dongmei , Lu Yixin , Meng Yuezhong
Published: October 2011

A series of diatomite‐immobilized Cu–Ni bimetallic nanocatalysts was prepared under ultrasonication and evaluated for the direct synthesis of dimethyl carbonate under various conditions. Upon being fully characterized by TPR, TPD, BET, SEM, XRD, and XPS methodologies, it is found that the bimetallic composite is effectively alloyed and well immobilized inside or outside the pore of diatomite. Under the optimal conditions of 1.2 MPa and 120∘C, the prepared catalyst with loading of 15% exhibited the highest methanol conversion of 6.50% with DMC selectivity of 91.2% as well as more than 10‐hour lifetime. The possible reaction mechanism was proposed and discussed in detail. To our knowledge, this is the first report to use diatomite as a catalyst support for direct DMC synthesis from methanol and CO2.