bluuebunny/crossref_metadata_2025 huggingface dataset:
Mask Pattern Correction by Energy Loss Compensation in Extreme Ultraviolet Lithography
Authors: Sugawara Minoru , Nishiyama Iwao , Takai Mikio
Published: September 2005

In extreme ultraviolet (EUV) lithography with off-axis incidence, the incident light loses energy when it is reflected from a mask onto a wafer because the absorber pattern blocks some of the incident and diffracted light, and the absorber side wall reflects some of the incident light. This study concerns mask pattern correction to compensate for the energy loss at the pupil. Simple negative biasing was found to be an effective compensation technique. That is, when the absorber stack is thin, a narrowed mask pattern by adding a negative bias and off-axis incidence produce about the same optical proximity effects (OPE) as an unbiased mask and normal incidence. This makes it possible to use conventional algorithms for optical proximity effect correction (OPC), which are optimized for normal incidence. For a thin absorber stack, combining energy loss compensation for off-axis incidence with conventional OPC for normal incidence provides excellent pattern fidelity, sufficient critical dimension (CD) uniformity, and good pattern edge contrast at the same time.
Large-Area X-ray Lithography System for LIGA Process Operating in Wide Energy Range of Synchrotron Radiation
Authors: Utsumi Yuichi , Kishimoto Takefumi , Hattori Tadashi , Hara Hirotsugu
Published: September 2005

We developed a new X-ray lithography system for the lithographite, galvanoformung and abformung process (LIGA process) using synchrotron radiation at the NewSUBARU facility of the University of Hyogo. The X-ray lithography system can utilize two different energy regions: one is a high-energy region: from 2 keV to 12 keV, and the other is a low-energy region from 1 to 2 keV. Each energy region can be selected in accordance with the size and shape of the desired microstructures. Large-area patterning across an A4-size area was successfully performed with a highly uniform pattern thickness. Furthermore, high-aspect-ratio patterning using a high-X-ray-energy region was also achieved using this X-ray lithography system.
Tool-Induced Shift and Pupil Transmittance Distribution in Measurement Optics
Authors: Sugaya Ayako , Nagayama Tadashi , Masada Takahiro
Published: September 2005

To advance large scale integrated circuit (LSI), alignment optics of an exposure system must be highly accurate. To satisfy this requirement, amplitude error in the optics is studied and analyzed. The factor in amplitude error that causes measurement errors is the asymmetrical brightness distribution in numerical aperture (NA) of the beam at the detector surface. A method that measures the amplitude error and phase error separately is presented. The measurement errors caused by amplitude error are studied. For the pattern that is needed for progress on LSI, these errors tend to be large. In order to minimize these errors, our alignment technique is studied. We demonstrate that focus optimization of a field image alignment sensor (FIA). FIA focus optimization (FFO) is effective in reducing errors, especially errors dependent on focus, caused by pupil transmittance distribution. The advantages of FFO for future-generation LSI production are confirmed.
Experimental Evaluation of Arrayed Microcolumns with Monolithic Structure
Authors: Jeong Jin Woo , Kim Dae Jun , Kim Ho Seob , Choi Sang Kuk , Kim Dae Yong , Lee Hyeong Rag
Published: September 2005

A 2×2 arrayed microcolumn structure based on a monolithic deflector was evaluated experimentally. The microcolumns of this structure consist of electron emission tungsten tips, silicon membrane microlenses, double silicon deflectors, and Cu grid samples. The assembly of the microlens and column component was performed on a custom-built alignment unit consisting of an optical microscope, an alignment jig, and a motor-driven micromanipulator. The alignment of the tungsten tip and microlens hole is performed under direct observation with two perpendicularly aligned microscopes. Microlenses and deflectors (silicon octupoles) are mounted on a low temperature co-fired ceramic (LTCC) substrate. The three-dimensional interconnection structure of the LTCC substrate provides common wiring for each double octupole for synchronous operation. Each deflector was operated with same voltage sources. The 2×2 arrayed microcolumns were tested in three modes; single column, independent, and parallel mode, and the properties of these modes were compared.
Technology for Fabrication of Nanostructures by Standard Cleanroom Processing and Nanoimprint Lithography
Authors: Bilenberg Brian , Jacobsen Søren , Pastore Carine , Nielsen Theodor , Enghoff Simon Riis , Jeppesen Claus , Larsen Asger Vig , Kristensen Anders
Published: September 2005

Sub-micron structures are routinely fabricated by electron beam lithography (EBL). However EBL is a time consuming and costly technology. We present a technology for fabrication of nanostructures by standard UV-lithography and thermal nanoimprint lithography (NIL). NIL-stamps with sub-30 nm patterns are fabricated by standard micrometer resolution cleanroom processing, i.e. UV-lithography, reactive ion etching and thermal oxidation, and the pattern is transferred to a polymer thin film on a substrate by NIL. Subsequently the patterned polymer film is used either as a direct etching mask to transfer the pattern to the substrate or as a metal lift-off mask. This way we have demonstrated the fabrication of sub-100 nm nanochannels in silicon oxide and sub-50 nm gold lines on silicon.
Vertically Aligned Carbon Nanotubes Grown at Low Temperatures for Use in Displays
Authors: Takeda Goichi , Pan Lujun , Akita Seiji , Nakayama Yoshikazu
Published: September 2005

Vertically aligned carbon nanotubes (CNTs) have been synthesized by chemical vapor deposition at low temperatures between 450°C to 550°C for use as display emitters. It has been found that preheating the reaction gas C2H2 at 700°C enhances its reactivity and contributes to the effective decomposition of the gas on the surfaces of catalyst particles heated even at 450°C. We have also found that the catalyst activity is strongly affected by the film thickness and the thickness ratio of layered catalysts, which are Co and Ti in this study. Long CNTs have been obtained when the thicknesses of Co and Ti are reduced. It has been observed that the turn-on voltage of the field emission from the CNTs prepared at low temperatures is similar to that from the CNTs prepared at high temperatures.
Hot Carrier Effect in UltraThin Gate Oxide Metal Oxide Semiconductor Field Effect Transistor
Authors: Uraoka Yukiharu , Honda Hiroyuki , Fuyuki Takashi , Sasaki Takaoki , Yasuhira Mitsuo
Published: September 2005

We have analyzed the degradation introduced by the hot-carrier effect in an ultrathin gate oxide n-channel metal oxide semiconductor field effect transistor (MOSFET). To investigate the hot-carrier effect, stress bias dependence on degradation was measured. From the stress gate bias and stress drain bias dependences, we found that the drain avalanche effect dominated the degradation. The gate length dependence was evaluated with MOSFET of various gate lengths. With decreasing gate length, degradation became remarkable, particularly at less than 100 nm. In a MOSFET with a smaller gate length, we speculated that the damaged region is expanded from the drain region to the source region. By device simulation, we found that a potential hole was observed in the source region that corresponded to a “pocket” profile, and that lines of force terminate there. By emission microscope, we found that hot carriers are generated. This phenomenon supports the results of a stress test and device simulation. We proposed a new model that explains experimental and theoretical results consistently.
Morphological Stability of Si(001) Surface Immersed in Fluid Mixture of Ultrapure Water and Silica Powder Particles in Elastic Emission Machining
Authors: Kubota Akihisa , Mimura Hidekazu , Inagaki Kouji , Yumoto Hirokatsu , Mori Yuzo , Yamauchi Kazuto
Published: September 2005

We examined the Si(001) surface after immersion in a mixture of ultrapure water and silica powder particles by atomic force microscopy (AFM), spectroscopic ellipsometry and electron spectroscopy for chemical analysis (ESCA). The surface etching of Si(001) in the mixture fluid is found to be markedly suppressed, although the surface etching of Si(001) under aqueous conditions proceeds constantly. The surface microroughness after immersion in the mixture fluid can be maintained in the state it was in before immersion. It is suggested that the existence of silica powder particles in the ultrapure water affects the stability of the Si(001) surface morphology.
Electronic and Excitonic Structures of Inorganic–Organic Perovskite-Type Quantum-Well Crystal (C4H9NH3)2PbBr4
Authors: Tanaka Kenichiro , Takahashi Takayuki , Kondo Takashi , Umeda Kenichi , Ema Kazuhiro , Umebayashi Tsutomu , Asai Keisuke , Uchida Kazuhito , Miura Noboru
Published: September 2005

The electronic and excitonic structures of an inorganic–organic perovskite-type quantum-well crystal (C4H9NH3)2PbBr4 have been investigated by optical absorption, photoluminescence, electroabsorption, two-photon absorption, and magnetoabsorption spectroscopies. Excitons in (C4H9NH3)2PbBr4 are of the Wannier-type, and ns (n≥2) excitons form an ideal two-dimensional Wannier exciton system. The binding energy, longitudinal–transverse splitting energy, and exchange energy of 1s excitons have been determined to be 480, 70 and 31 meV, respectively. These high values originate from both a strong two-dimensional confinement and the image charge effect. These values are larger than those in (C6H13NH3)2PbI4, owing to the smaller dielectric constant of the well layer in (C4H9NH3)2PbBr4 than that in (C6H13NH3)2PbI4. The seemingly unusual electric-field dependence of excitons resonance is also reasonably understood by taking the image charge effect into account.
Theoretical Investigation of Dielectric Constant and Elastic Modulus of Three-Dimensional Isotropic Porous Silica Films with Cubic and Disordered Pore Arrangements
Authors: Miyoshi Hidenori , Yamada Kazuhiro , Kohmura Kazuo , Fujii Nobutoshi , Matsuo Hisanori , Tanaka Hirofumi , Oku Yoshiaki , Seino Yutaka , Hata Nobuhiro , Kikkawa Takamaro
Published: September 2005

The dielectric constant (k) and elastic modulus (E) of self-assembled three-dimensional porous silica films were investigated by analytical and numerical calculations to reveal the relationship between k and E. It was found that cubic pore arrangements have E values higher than those of random pore arrangements and two-dimensional periodic hexagonal pore arrangements for the same k. It was also found that disordered isotropic porous silica films having cylindrical pores with well-controlled pore size distributions exhibit an E vs k relationship similar to that of two-dimensional hexagonal periodic porous silica films. The elastic modulus of the skeletal silica was determined to be 40 GPa from the combination of the calculated results and experimental data on ultralow-k disordered porous silica film with a k value of 2.0 and a modulus of 8 GPa.
Lasing Characteristics of InGaAsSbN Quantum Well Laser Diodes at 2-µm-Wavelength Region Grown on InP Substrates
Authors: Kawamura Yuichi , Nakagawa Tomokatsu , Inoue Naohisa
Published: September 2005

InGaAsSbN quantum well laser diodes operating at a 2-µm-wavelength region were grown by molecular beam epitaxy (MBE) on InP substrates and their characteristics were studied. Two types of laser diode with different Sb compositions of 0.014 and 0.14 were compared, where the N composition was fixed at 0.014. It was found that an increase in Sb composition induces a marked redshift of the emission wavelength and a reduction in lasing threshold current density.
Expanded-Core Planar Waveguide in Variable Optical Attenuator
Authors: Kim Sungchul
Published: September 2005

A novel structure of a variable optical attenuator is proposed. It is composed of planar waveguides as optical media and a micro-electro-mechanical system (MEMS) comb actuator with a light blocking bar as the light attenuator. The core of the planar optical waveguide is gradually expanded such that single-mode operation is maintained. The results of the analyses of the optical properties of a planar waveguide MEMS optical attenuator by an optical simulation–beam propagation method (BPM) are presented. The insertion loss, polarization-dependent loss, and wavelength-dependent loss of this attenuator are analyzed. The optimized design parameters for an expanded-core waveguide are determined through the BPM with consideration of optical losses.
Fiber-Bragg-Grating-Based Optical Code-Division Multiple Access Passive Optical Network Using Dual-Baseband Modulation Scheme
Authors: Lin Wen-Piao , Wu He-Long
Published: September 2005

We propose a fiber-Bragg-grating (FBG)-based optical code-division multiple access passive optical network (OCDMA-PON) using a dual-baseband modulation scheme. A mathematical model is developed to study the performance of this scheme. According to the analyzed results, this scheme can allow a tolerance of the spectral power distortion (SPD) ratio of 25% with a bit error rate (BER) of 10-9 when the modified pseudorandom noise (PN) code length is 16. Moreover, we set up a simulated system to evaluate the baseband and radio frequency (RF) band transmission characteristics. The simulation results demonstrate that our proposed OCDMA-PON can provide a cost-effective and scalable fiber-to-the-home solution.
Investigation into the Seebeck Coefficient in a Two-Layer Assembly during Laser Short-Pulse Heating
Authors: Yilbas Bekir S. , Kassas M.
Published: September 2005

The Seebeck coefficient in a substrate varies with electron temperature such that it increases with increasing temperature. The Seebeck coefficient for different materials differs even though the materials have similar thermal properties. In this study, the Seebeck coefficient in a two-layer assembly exposed to laser short-pulse heating is considered. The assembly consists of gold and copper, and the gold layer is situated on top of the copper. In order to investigate the change in the Seebeck coefficient with layer thickness, three different thicknesses of gold layer are accommodated in the simulations. An abrupt change in the Seebeck coefficient occurs across the layers, despite the smooth decay of electron temperatures in this region due to the similar thermal properties of the layer materials. Consequently, the Seebeck coefficient variation across the layers can form the basis for measurement of layer thickness.
Optical Trapping and Manipulation System Using Liquid-Crystal Lens with Focusing and Deflection Properties
Authors: Kawamura Marenori , Ye Mao , Sato Susumu
Published: September 2005

We propose a laser manipulation system using a liquid-crystal (LC) lens with variable-focusing and beam deflection functions for the transmitted laser beam. Three-dimensional trapping and manipulation of microscopic particles can be demonstrated by focusing and deflecting the laser beam, and the position of the captured particles can be controlled by adjusting the applied voltage without any mechanical movements.
Kinetic Model of Si Oxidation at HfO2/Si Interface with Post Deposition Annealing
Authors: Shimizu Haruka , Kita Koji , Kyuno Kentaro , Toriumi Akira
Published: September 2005

The oxidation mechanism at the HfO2/Si interface is discussed by investigating oxidation kinetics on the basis of experimental results that were obtained using the technique of grazing incidence X-ray reflectivity (GIXR) in combination with spectroscopic ellipsometry (SE) measurements. In a relatively thick HfO2 region, the interface layer growth shows a logarithmic dependence on annealing time, while the activation energy of oxidation is very small compared with that of conventional oxidation. These results clearly indicate that the oxidation mechanism at the HfO2/Si interface is different from that at the Si surface. Moreover, it is also reported that the oxidation at the HfO2/Si interface has no surface orientation dependence, no HfO2 thickness dependence and a slight O2 pressure dependence. All of the results obtained in this work suggest that atomic oxygen is involved in the oxidation at the HfO2/Si interface and the diffusion of oxygen atoms in the interface layer limits oxidation rate in a relatively thick HfO2 region. On the other hand, in an ultra-thin HfO2 region, HfO2 thickness dependence and Si surface orientation dependence are observed. These results suggest that both atomic oxygen and molecular oxygen are involved in the interface oxidation in an ultra-thin HfO2 region. On the basis of the results, we propose a kinetic model for the oxidation associated with both atomic oxygen and molecular oxygen at the HfO2/Si interface.
Modeling and Characterization of Piezoelectric Fibers with Metal Core
Authors: Sebald Gael , Qiu Jinhao , Guyomar Daniel , Hoshi Daisuke
Published: September 2005

A simple physical model of the first vibration mode of piezoelectric fibers with a metal core is developed for predicting their properties from the parameters of constituents. It is shown that the metal core diameter influences the piezoelectric properties of the fiber only to a lesser extent for diameter ratios lower than 0.3. The good accuracy of the model is confirmed by finite element modeling (FEM). A characterization procedure for actual fibers is then proposed. The properties of the piezoceramic constituent can be deduced from the fiber behavior, which is a precious tool for checking fiber quality. This procedure is applied to experimental Pb(Nb,Ni)O3–Pb(Zr,Ti)O3 fibers with a platinum core. The actual d
31 is -112 pC/N for the ceramic phase of the fiber instead of -246 pC/N for the bulk material. It is believed that the poling process (constraints due to the metal core) and the density optimization are the two key factors for improving these performances.
Basic and Applied Aspects of Color Tuning of Bioluminescence Systems
Authors: Ohmiya Yoshihiro
Published: September 2005

V. Viviani et al. [Biochemistry 38 (1999) 8271] were the first to succeed in cloning the red-emitting enzyme from the South American railroad worm, which is the only bioluminescent organism known to emit a red-colored light. The application of red bioluminescence has been our goal because the transmittance of longer-wavelength light is superior to that of the other colors for visualization of biological functions in living cells. Now, different color luciferases, which emit with wavelength maxima ranging from 400 to 630 nm, are available and are being used. For example, based on different color luciferases, Nakajima et al. developed a tricolor reporter in vitro assay system based on these different color luciferases in which the expression of three genes can be monitored simultaneously. On the other hand, bioluminescence resonance energy transfer (BRET) is a natural phenomenon caused by the intermolecular interaction between a bioluminescent protein and a fluorophore on a second protein, resulting in the light from the bioluminescence reaction having the spectrum of the fluorophore. Otsuji et al. [Anal. Biochem. 329 (2004) 230] showed that the change in the efficiency of energy transfer in intramolecular BRET can quantify cellular functions in living cells. In this review, I introduce the basic mechanisms of color tuning in bioluminescent systems and new applications based on color tuning in the life sciences.
Drain/Gate-Voltage-Dependent On-Current and Off-Current Instabilities in Polycrystalline Silicon Thin-Film Transistors under Electrical Stress
Authors: Wang Shen De , Chang Tzu Yun , Lo Wei Hsiang , Sang Jen Yi , Lei Tan Fu
Published: September 2005

The On-current (I
on) and Off-current (I
off) instabilities of polycrystalline silicon thin-film transistors (poly-Si TFTs) were investigated under various stress conditions. The stress-induced device degradation was studied by measuring the dependences of I
on and I
off on the drain/gate voltages. From the results, dissimilar variations in I
on and I
off were observed. The differences can be attributed to the variances in the amount of trap charges in the gate oxide and the spatial distributions of the trap states generated in the poly-Si channel. A comprehensive model for the degradation of I
on and I
off in poly-Si TFTs under various electrical stress conditions was suggested.
Force-Sensing Scheme for Small Mechanical Signals in Complementary Metal Oxide Semiconductor Microelectromechanical System Fingerprint Sensor
Authors: Sato Norio , Morimura Hiroki , Shigematsu Satoshi , Yano Masaki , Kudou Kazuhisa , Kamei Toshikazu , Machida Katsuyuki
Published: September 2005

This paper proposes a force-sensing scheme with a microelectromechanical systems (MEMS) structure and a complementary metal oxide semiconductor (CMOS) amplifier for small pixels where the force from the ridges of a finger surface is detected. The MEMS structure features T-shaped protrusions on parallel electrodes facing each other and converts mechanical signals of force into electrical signals of capacitance change most efficiently. The CMOS amplifier extracts the capacitance change distinguished from the original capacitance. Calculations and measurements of the fabricated sensors show that the new MEMS structure in small 50-µm-square pixels can produce as large a capacitance change as 2 fF with a force of 1200 µN/pixel, which corresponds to about 0.5 MPa of finger pressure. The CMOS amplifier cancels out the original capacitance and converts the capacitance change of 2 fF into an output voltage change of about 0.1 V. Thus, the force-sensing scheme totally enhances the sensitivity of the CMOS MEMS fingerprint sensors regardless of the small size of the pixels.
DC Characteristics in High-Quality AlGaN/AlN/GaN High-Electron-Mobility Transistors Grown on AlN/Sapphire Templates
Authors: Miyoshi Makoto , Imanishi Atsushi , Egawa Takashi , Ishikawa Hiroyasu , Asai Kei-ichiro , Shibata Tomohiko , Tanaka Mitsuhiro , Oda Osamu
Published: September 2005

High-crystal-quality Al0.26Ga0.74N/AlN/GaN structures with a very high mobility, such as over 2100 cm2/(V s) with a two-dimensional-electron gas (2DEG) density of approximately 1×1013/cm2, were grown on epitaxial AlN/sapphire templates by metalorganic vapor phase epitaxy and adopted for the fabrication of high-electron-mobility transistors (HEMTs). The fabricated devices showed good DC characteristics compared with those in conventional AlGaN/GaN HEMTs and in devices grown on sapphire substrates. Also, it was confirmed that further improvements in DC characteristics are achieved by applying recessed ohmic contacts to AlGaN/AlN/GaN HEMTs. A high extrinsic transconductance of approximately 220 mS/mm and a high drain current density of over 1 A/mm with a threshold voltage of -4.08 V were obtained for 1.5-µm-gate-length recessed ohmic AlGaN/AlN/GaN HEMTs on AlN/sapphire templates. In addition, it was found that the gate leakage current of HEMTs can be suppressed by using epitaxial AlN/sapphire templates as substrates.
β-FeSi2 Continuous Films Prepared on Corning 7059 Glass by RF-Magnetron Sputtering
Authors: Okuda Yukiko , Momose Noritaka , Takahashi Masashi , Hashimoto Yoshio , Ito Kentaro
Published: September 2005

More than 1-µm-thick single-phase β-FeSi2 continuous films on Corning 7059 glass and quartz have been obtained by an easy method. We controlled the Si/Fe composition ratio of Fe–Si precursor using a Si target with sectorial Fe plates placed on it. Both surface flatness of the film and β-FeSi2/substrate interface were satisfactory, and cracks were not observed by secondary ion microscopy. Suitable electric properties of β-FeSi2 for solar cell absorption layers ( p-type, 5 Ω·cm, 40 cm/(V ·s), and 1 ×1017 cm-3) were obtained from a Si/Fe=1.7 Fe-rich precursor.
Frequency Resolved Optical Gating Studies of Strained Saturable Bragg Reflector: Anomalous Dispersion near Resonance Absorption of the Exciton Resonance
Authors: Lee Chao-Kuei , Liu Tze-An , Huang Kai-Fung , Pan Ci-Ling
Published: September 2005

A strained saturable Bragg reflector (SSBR) for passive mode-locking of Ti:sapphire lasers was investigated by the frequency resolved optical gating (FROG) technique. Incident pulses of several wavelengths and with zero, positive, or negative chirp were employed. A considerable pulse shortening near the excitonic resonance of the strained quantum well was observed and attributed to anomalous dispersion due to resonance absorption. On the long wavelength side of exciton resonance, however, the chirp of the reflected pulse showed a weak wavelength dependence attributed to the material dispersion of SSBR in pulse broadening was obtained.
Element-Selective Observation of Electronic Structure Transition between Semiconducting and Metallic States in Boron-Doped Diamond Using Soft X-ray Emission and Absorption Spectroscopy
Authors: Iihara Junji , Muramatsu Yasuji , Takebe Toshihiko , Sawamura Akitaka , Namba Akihiko , Imai Takahiro , Denlinger Jonathan D. , Perera Rupert C. C.
Published: September 2005

The electronic structure transition between the semiconducting and metallic states in boron (B)-doped diamonds was element-selectively observed by soft X-ray emission and absorption spectroscopy using synchrotron radiation. For lightly B-doped diamonds, the B 2p-density of states (DOS) in the valence band was enhanced with a steep-edge feature near the Fermi level, and localized acceptor levels, which are characteristic of semiconductors, were clearly observed both in B 2p- and C 2p-DOS in the conduction bands. For heavily B-doped diamonds, the localized acceptor levels developed into extended energy levels and the new energy levels generated formed an extended conduction band structure that overlapped with the valence band. Thus, the metallic energy band structure is actually formed by heavy boron doping. These valence and conduction band structures observed by soft X-ray emission and absorption spectroscopy accounted for the electrical properties of B-doped diamonds.
Ferroelectric Properties of Pt/Pb5Ge3O11/Pt and Pt/Pb5Ge3O11/HfO2/Si Structures
Authors: Ohara Shuichiro , Aizawa Koji , Ishiwara Hiroshi
Published: September 2005

The ferroelectric properties of metal–ferroelectric–metal (MFM) capacitors with a Pt/Pb5Ge3O11(PGO)/Pt structure and metal–ferroelectric–insulator–semiconductor (MFIS) diodes with a Pt/PGO/HfO2/Si structure were investigated. C-axis-oriented PGO thin films were formed on both Pt/SiO2/Si and HfO2 (6 nm)/Si structures by a sol–gel method. Typical values of remanent polarization (2P
r), coercive field (2E
c), and dielectric constant in the MFM capacitors were 5.7 µC/cm2, 63 kV/cm, and 50, respectively, and the remanent polarization gradually increased with the switching pulses for up to 1 ×1010 cycles. It was also found that the memory window in the MFIS diodes with a 340-nm-thick PGO film was as large as 1.3 V.
Voltage-Tunable Dielectric Properties of Pyrochlore Bi–Zn–Nb–Ti–O Solid-Solution Thin Films
Authors: Kim Jin Young , Kim Dong-Wan , Jung Hyun Suk , Hong Kug Sun
Published: September 2005

The structural and dielectric properties of Bi2Ti2O7–Zn2Nb2O7 solid-solution thin films were investigated using (Bi2-x
Zn
x
)(Nb
x
Ti2-x
)O7 (BZNT, 0.05≤x≤1.0) pyrochlore thin films prepared on platinized Si substrates by metalorganic decomposition (MOD) process. Thermal analysis and X-ray diffraction (XRD) results confirmed that the crystallization of the BZNT thin films started below 600°C and was completed at approximately 750°C. Broad ranges of single-phase solid-solutions based on cubic (Bi1.5Zn0.5)(Nb0.5Ti1.5)O7 were observed with x values from 0.1 to 0.7. Compared with bulk ceramics, a restriction in the lattice shrinkage of BZNT thin films with x values under 0.5 was apparent, which may have introduced internal stress in the thin films and eventually affected the dielectric properties of BZNT thin films. The BZNT thin films investigated had dielectric constants in the range of 142–242, and the maximum dielectric constant was 242 when x=0.5. Room-temperature capacitance–voltage measurements at 1 MHz demonstrated a tunability of 30%, with a zero-bias tan
δ of 0.005.
Frequency–Temperature Characteristics of AT-Cut Crystal Resonator and Oscillator Utilizing Relaxator Ceramic as Load Capacitor
Authors: Oh Dongon , Mun Keyonghyeon , Lee Hyunseok , Yoo Juhyun
Published: September 2005

In this study, a simple AT-cut crystal resonator and an oscillator utilizing a Bi0.5(Na0.84K0.16)0.5TiO3 relaxator ceramic as a load capacitor were designed and their frequency–temperature characteristics were investigated. To modify the temperature dependence of the dielectric constant, Bi0.5(Na0.84K0.16)0.5TiO3 ceramics were manufactured with variations in the level of Sr substitution. At a composition with 6 mol % Sr substitution as a load capacitor, the frequency–temperature characteristics of the AT-cut crystal resonator and oscillator with a series load capacitance were varied similarly to those of cut orientation variation, and also compensated.
Electrical Properties of Anodically Oxidized Nb2O5 and Si-Doped Nb2O5 Films
Authors: Shimizu Hirofumi , Sato Hirohumi , Nishimura Shigeoki , Honda Mitsutoshi
Published: September 2005

The basic electrical properties of Nb2O5 and Si-doped Nb2O5 (Nb2O5–Si) thin films, which were obtained by anodically oxidizing Nb in an H3PO4 solution, were investigated using their current–voltage (I–V) and capacitance–voltage (C–V) characteristics with the aim of determining their electrical conduction mechanism. In the forward bias condition, Poole–Frenkel conduction is plausible for both Nb2O5 and Nb2O5–Si (Si-doping less than 19 at. %). For the reverse bias condition, a Schottky-barrier is formed at the Au/Nb2O5 and/or Au/Nb2O5–Si interface (Si-doping less than 5 at. %) because of the difference in the work function. The low frequency capacitance (1 kHz) increased with forward bias due to the lifetime of the carriers (electrons, holes, or both) injected into the Nb2O5 and/or Nb2O5–Si films. A schematic energy band diagram for Au/Nb2O5/Nb and/or Au/Nb2O5–Si/Nb–Si (Si doping less than 5 at. %) capacitor structures is hypothesized in order to explain the I–V and C–V characteristics.
Landau Theory of Phase Transition in Ferroelectric Vinylidene Fluoride/Trifluoroethylene Copolymer Single Crystals: Hysteresis Loop
Authors: Iwata Makoto , Ishibashi Yoshihiro
Published: September 2005

Ferroelectric hysteresis loops in vinylidene fluoride/trifluoroethylene, P[VDF/TrFE], copolymer single crystals are discussed on the basis of the Landau-type free energy function with the anisotropy parameter γ2. It was found that the coercive field strongly depends on the value of γ2, and decreases as γ2=0 is approached, because the Landau-type free energy function becomes isotropic in the order parameter space. We successfully reproduced the p–E hysteresis loop with a square shape and a small coercive field in P[VDF/TrFE] on the basis of the Landau theory with the anisotropy parameter γ2.
Stability-Enhanced Pixel Isolation Method for Flexible Liquid Crystal Displays
Authors: Jang Se-Jin , Jung Jong-Wook , Kim Hak-Rin , Jin Minyoung , Kim Jae-Hoon
Published: September 2005

We proposed a new method of enhancing the stability of a liquid crystal (LC) mode for flexible display applications. In the device, LC molecules are isolated in pixels where LCs are surrounded by a microstructure produced by a stamping method with a durable elastomer such as poly(dimethylsiloxane) (PDMS). Two substrates are tightly attached by a solidified polymer layer produced by anisotropic phase separation from LC/polymer composites. The electrooptic characteristics of our sample are comparable to those of a normal sample without a PDMS microstructure. This method can be applicable to the fabrication of large plastic LCDs using a roll-to-roll process.
Elastic Anomaly of Glass Transitions in Lithium Silicate
Authors: Hushur Anwar , Kojima Seiji , Kodama Masao , Whittington Ben , Olesiak Marty , Affatigato Mario , Feller Steven A.
Published: September 2005

Brillouin spectra of lithium silicate glasses with various lithium oxide concentrations have been investigated over a wide temperature range. The room-temperature elastic constants increase significantly with increasing lithium oxide concentration. This indicates that rigidity increases with lithium oxide concentration. From the temperature dependence of the longitudinal elastic modulus, it was found that the rigidity decreases on heating, faster with a high lithium content. The rate of decrease becomes significantly larger above the glass transition temperature T
g. This is related to the disruption of network bonds, suppressing the rigidity of the melt structures on heating. The increased lithium oxide concentration leads to a faster degradation in the network structure. The T
g of lithium silicate glasses was determined. The increased fragility with increased lithium oxide concentration reflects the significant decrease in longitudinal elastic modulus with temperatures above T
g. Crystallization temperature decreases with increasing lithium oxide concentration.
Analysis of Reflective Part with Wide-Band Property in Single Gap Transflective Fringe-Field Switching Mode
Authors: Park Jun Baek , Kim Hyang Yul , Jeong Youn Hak , Lim Dong Hoon , Kim Seo Yun , Lim Young Jin , Lee Seung Hee
Published: September 2005

This study investigates reflective mode with wide-band property using liquid crystal (LC) cell (λ/2) and inner retarder (λ/4). In wide-band type, the maximum contrast ratio increases and viewing angle decreases compared with the case that slow axis of LC and the transmission axis of analyzer coincide. However, for perfect dark state, the retardation of LC cell should be kept 0.275 µm. If not, maximum CR decreases from 150 to 100.
Microwave Dielectric Properties and Microstructures of 0.5La(Mg1/2Ti1/2)O3–0.5CaTiO3 Ceramics with B2O3 Addition
Authors: Huang Cheng-Liang , Chen Yuan-Bin , Lo Ching-Wen
Published: September 2005

La(Mg1/2Ti1/2)O3-based ceramics are prepared with a conventional solid-state route. With 50 mol % CaTiO3 addition, 0.5La(Mg1/2Ti1/2)O3–0.5CaTiO3 ceramics with 0.25 wt % B2O3
ε
r value of ∼ 42.92–43.38, Q ×f values of ∼24000 (at 7 GHz) and τf values of ∼-8.9 ppm/°C. However, the sintering temperature remains above 1400°C. Doping with B2O3 (up to 1 wt %) can effectively promote the densification and improve the dielectric properties of 0.5La(Mg1/2Ti1/2)O3–0.5CaTiO3 ceramics. The effects of a B2O3 additive on the microstructures, phase formation and microwave dielectric properties of La(Mg1/2Ti1/2)O3–CaTiO3 ceramics system are investigated. The Q ×f value of B2O3–doped 0.5La(Mg1/2Ti1/2)O3–0.5CaTiO3 ceramics can be improved to 28000 (at 8 GHz) at 1400°C due to the liquid-phase effect. The microwave dielectric properties are found to strongly correlate with the sintering temperature as well as the amount of B2O3 added.
Ti-Containing Amorphous Carbon Nanocomposite Coatings Prepared by Means of Eight-Target Arc-Assisted Middle Frequency Magnetron Sputtering
Authors: Yang Bing , Huang Zhihong , Liu Chuansheng , Zeng Zhaoyuan , Fan Xiangjun , Fu Dejun
Published: September 2005

Ti-containing amorphous carbon nanocomposite coatings were deposited by using a modified closed field twin unbalanced magnetron sputtering system which is arc assisted and consists of two circles of targets, in an Ar ambient and at a substrate temperature of 100°C High-resolution transmission electron microscopy shows that the coatings contain Ti nanocrystals embedded in the amorphous carbon matrix. Mechanical and tribological properties of the coatings are influenced by the substrate bias voltage and Ti pair-target current. For coatings prepared at a bias of 100 V, the hardness increases from 12 GPa at a Ti-target current of 4 A to 27 GPa at 15 A. The coating at 4 A exhibits very low friction coefficient (∼0.07) and excellent tribological performance with a wear rate of about 1.4×10-16 m3 N-1 m-1.
Temperature Dependence of Oxidation-Induced Changes of Work Function on Si(001)2×1 Surface Studied by Real-Time Ultraviolet Photoelectron Spectroscopy
Authors: Ogawa Shuichi , Takakuwa Yuji
Published: September 2005

At the initial stage of oxidation on a Si(001)2×1 surface, real-time ultraviolet photoelectron spectroscopy revealed that the O2 dosage dependences of band bending and work function due to a surface dipole layer show a distinct change with increasing temperature from 300 to 600°C in a Langmuir-type adsorption region, while oxygen uptake curves are almost the same at all temperatures examined. In constant to a dual-oxide-species (DOS) model in which the surface migration of adsorbed oxygen is not considered for Langmuir-type adsorption, the observed changes in work function due to the surface dipole layer mean that adsorbed oxygen can migrate on the surface more frequently with increasing temperature, leading to a decrease in the number of adsorbed oxygen atoms bonded at dimer backbond centers and furthermore a significant structural change of the oxide layer.
Achievement of High Density InAs Quantum Dots on InP (311)B Substrate Emitting at 1.55 µm
Authors: Caroff P. , Bertru N. , Corre A. Le , Dehaese O. , Rohel T. , Alghoraibi I. , Folliot H. , Loualiche S.
Published: September 2005

The As flux effect on InAs quantum dots formed by gas source molecular beam epitaxy on InP substrates, oriented following the (311)B crystallographic direction has been studied. Atomic force microscopy images show that the quantum dot (QD) density dramatically increases and quantum dot sizes decrease, when decreasing the As pressure. Moreover, the size dispersion is narrowed. Photoluminescence measurements on the high QD density samples is shifted to higher energy, toward the telecommunication important 1.55 µm emission.
Operating Characteristics of Polarization-Independent Active Birefringent Fiber Loop Filter Using Two Traveling-Wave-Type Ultrafast Phase Modulators
Authors: Onodera Noriaki , Tsuji Kenichiro , Saruwatari Masatoshi
Published: September 2005

Polarization-independent active birefringent optical fiber loop filters using two traveling-wave-type phase modulators are studied theoretically and experimentally. Theoretical analysis based on the Jones Matrix method reveals that polarization-independent operation requires a bidirectional phase modulator that is usually realized by the lumped-circuit-type modulator with a low response speed. To obtain an ultrahigh operating speed, we introduce a simple configuration in which two traveling-wave-type phase modulators are cascaded in series but with opposite traveling-wave directions. As a result, polarization-independent, high-speed modulation/wavelength switching characteristics are realized.
Terahertz Properties of a New Organic Crystal, 4'-Dimethylamino-N-methyl-4-stilbazolium p-Chlorobenzenesulfonate
Authors: Taniuchi Tetsuo , Ikeda Satoshi , Mineno Yoshihiro , Okada Shuji , Nakanishi Hachiro
Published: September 2005

We investigated terahertz (THz) properties of a new organic crystal, 4'-dimethylamino-N-methyl-4-stilbazolium p-chlorobenzenesulfonate (DASC). High-quality DASC crystals were grown using a slow-cooling method in methanol solution. Tunable THz waves over a wide range of 2 to 19 THz were generated in DASC crystals by difference-frequency mixing. The highest THz energy of 520 nJ was obtained at 11.3 THz. THz properties of DASC were compared with those of the conventional 4'-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST).
Electrical Conductivity of Lambda DNA–Pd Wire
Authors: Hosogi Maho , Hashiguchi Gen , Haga Masa-aki , Yonezawa Tetsu , Kakushima Kuniyuki , Fujita Hiroyuki
Published: September 2005

We investigated the electric conduction of lambda DNA molecules covered with Pd colloids using micromachined DNA tweezers that has a pair of opposing probes for retrieving DNA molecules. The molecules were retrieved from a solution containing lambda DNA by applying RF power between the probes in the solution. The retrieved molecules were then soaked in a colloidal solution containing cationic Pd particles, which results in a DNA–Pd wire bridged between the tweezer probes. Current–voltage curves for the DNA–Pd wire can be measured between the DNA tweezers probes, and the resistivity of the DNA–Pd wire was approximately 74 Ω cm.
Highly Tunable Emission from Strain-Induced InGaAsP/InP Quantum Dots
Authors: Riikonen Juha , Sormunen Jaakko , Koskenvaara Hannu , Mattila Marco , Sopanen Markku , Lipsanen Harri
Published: September 2005

Low-temperature photoluminescence (PL), tunable between 1.3 and 1.7 µm, is obtained from strain-induced quantum dots (SIQDs). The quantum dots are fabricated by growing self-assembled InAs stressor islands on top of a near-surface InGaAs(P)/InP quantum well (QW). The structure is tuned by varying the composition of the QW and its distance from the surface. Time-resolved PL measurements reveal that QD relaxation and recombination time constants (0.55 and 0.50 ns) are virtually independent of the composition of the nearly lattice-matched InGaAsP layer. Also, decreasing the QW distance from the surface is shown to shift the energy states and significantly diminish the PL intensity of the SIQD.
Oxidant stress suppresses CFTR expression
Authors: Cantin André M. , Bilodeau Ginette , Ouellet Cristine , Liao Jie , Hanrahan John W.
Published: September 2005

Epithelial mucous membranes are repeatedly exposed to oxidants and xenobiotics. CFTR plays a role in glutathione transepithelial flux and in defining the hydration and viscoelasticity of protective mucus. We therefore hypothesized that CFTR expression and function may be modulated by oxidant stress. A sublethal oxidant stress ( tert-butylhydroquinone, BHQ) in CFTR-expressing epithelial cells (T84) induced a significant increase in cellular glutathione that was associated with an increase in expression of the gene encoding the heavy subunit of the rate-limiting enzyme for glutathione synthesis, γ-glutamylcysteine synthetase (γ-GCShs). CFTR gene expression was markedly decreased according to a time course that mirrored the changes in γ-GCShs. Western blot analysis confirmed that the decrease in CFTR gene expression was associated with a decrease in CFTR protein. cAMP-dependent iodide efflux was also decreased by the oxidant stress. Nuclear run-on assays indicated that the oxidant stress had no effect on CFTR gene transcription, but the mRNA stability in the oxidant-stressed cells was markedly reduced. Furthermore, BHQ increased γ-GCShs mRNA while decreasing CFTR mRNA in Calu-3 cells, and taurine chloramine induced similar effects in T84 cells. We conclude that suppression of CFTR expression may represent an adaptive response of mucosal epithelium to an exogenous oxidant stress.
Expression of Kinase Suppressor of Ras1 Enhances Cisplatin-Induced Extracellular Signal–Regulated Kinase Activation and Cisplatin Sensitivity
Authors: Kim Min , Yan Ying , Kortum Robert L. , Stoeger Scott M. , Sgagias Magdalene K. , Lee Kwangmoon , Lewis Robert E. , Cowan Kenneth H.
Published: September 2005

Kinase suppressor of Ras1 (KSR1) interacts with several mitogen-activated protein (MAP) kinase pathway components, including Raf, MAP/extracellular signal–regulated kinase (ERK) kinase (MEK), and ERK, and acts as a positive regulator of the Ras signaling cascade. Previous studies have shown that exposure of cells to the anticancer agent cisplatin (cis-diamminedichloroplatinum, CDDP) is associated with changes in multiple signal transduction pathways, including c-Jun-NH2-kinase, ERK, and p38 pathways. Moreover, ERK activation has been linked to changes in cell survival following CDDP treatment. In this report, we have examined the effects of KSR1 expression on the sensitivity of cells to CDDP-induced apoptosis. Loss of KSR1 expression in mouse embryo fibroblasts (MEFs) derived from KSR1 knockout mice (KSR−/− MEF) is associated with decreased CDDP-induced ERK activation and increased resistance to CDDP-induced apoptosis compared with wild-type MEFs (KSR+/+ MEF). Furthermore, transduction of KSR−/− MEFs and MCF-7 breast cancer cells with wild-type KSR1 resulted in enhanced ERK activation following CDDP exposure and increased sensitivity to CDDP. In addition, inhibition of ERK activation by exposing MEFs to the MEK1/2-specific inhibitors PD98059 and U0126 protected both KSR+/+ and KSR−/− MEFs cells from CDDP-induced apoptosis. These results indicate that KSR1-mediated regulation of ERK activity represents a novel determinant of CDDP sensitivity of cancer cells.
Signaling Pathways Associated with Colonic Mucosa Hyperproliferation in Mice Overexpressing Gastrin Precursors
Authors: Ferrand Audrey , Bertrand Claudine , Portolan Ghislaine , Cui Guanglin , Carlson Jane , Pradayrol Lucien , Fourmy Daniel , Dufresne Marlene , Wang Timothy C. , Seva Catherine
Published: September 2005

MTI/G-Gly mice and hGAS mice, overexpressing glycine-extended gastrin (G-Gly) and progastrin, respectively, display colonic mucosa hyperplasia, hyperproliferation, and an increased susceptibility to intestinal neoplasia. Here, we have used these transgenic mice to analyze in vivo the modulation of intracellular signaling pathways that may be responsible for the proliferative effects of gastrin precursors. The expression, activation, and localization of signaling and cell-to-cell adhesion molecules were studied using immunofluorescence and Western blot techniques on colonic tissues derived from MTI/G-Gly, hGAS, or wild-type FVB/N mice. These analyses revealed an up-regulation of Src tyrosine kinase and related signaling pathways [phosphatidyl inositol 3′-kinase (PI3K)/Akt, Janus-activated kinase (JAK) 2, signal transducer and activator of transcription (STAT) 3, and extracellular-signal regulated kinases (ERK)] in both MTI/G-Gly and hGAS mice compared with the wild-type control animals as well as an overexpression of transforming growth factor-α (TGF-α). In contrast, overexpression of the gastrin precursors did not affect the activation status of STAT1 nor the expression and the distribution of adhesion proteins (focal adhesion kinase, cadherins, and catenins). We report for the first time that the transition from a normal colonic epithelium to a hyperproliferative epithelium in MTI/G-Gly and hGAS mice may be a consequence of the up-regulation of Src, PI3K/Akt, JAK2, STAT3, ERKs, and TGF-α. Deregulation of cell adhesion, a late event in tumor progression, does not occur in these transgenic models.
Secreted Protein Acidic and Rich in Cysteine Produced by Human Melanoma Cells Modulates Polymorphonuclear Leukocyte Recruitment and Antitumor Cytotoxic Capacity
Authors: Alvarez Mariano J. , Prada Federico , Salvatierra Edgardo , Bravo Alicia I. , Lutzky Viviana P. , Carbone Cecilia , Pitossi Fernando J. , Chuluyan H. Eduardo , Podhajcer Osvaldo L.
Published: September 2005

The expression of secreted protein acidic and rich in cysteine (SPARC) has been associated with the malignant progression of different types of human cancer. SPARC was associated with tumor cell capacity to migrate and invade, although its precise role in tumor progression is still elusive. In the present study, we show that SPARC produced by melanoma cells modulates the antitumor activity of polymorphonuclear leukocytes (PMN). Administration to nude mice of human melanoma cells in which SPARC expression was transiently or stably knocked down by antisense RNA (SPARC-sup cells) promoted PMN recruitment and obliterated tumor growth even when SPARC-sup cells accounted for only 10% of injected malignant cells. In addition, SPARC-sup cells stimulated the in vitro migration and triggered the antimelanoma cytotoxic capacity of human PMN, an effect that was reverted in the presence of SPARC purified from melanoma cells or by reexpressing SPARC in SPARC-sup cells. Leukotrienes, interleukin 8, and growth-related oncogene, in combination with Fas ligand and interleukin 1, mediated SPARC effects. These data indicate that SPARC plays an essential role in tumor evasion from immune surveillance through the inhibition of the antitumor PMN activity.