bluuebunny/crossref_metadata_2025 huggingface dataset:
Porohyperelastic Finite Element Modeling of Abdominal Aortic Aneurysms
Authors: Ayyalasomayajula Avinash , Vande Geest Jonathan P. , Simon Bruce R.
Published: August 2010

Abdominal aortic aneurysm (AAA) is the gradual weakening and dilation of the infrarenal aorta. This disease is progressive, asymptomatic, and can eventually lead to rupture—a catastrophic event leading to massive internal bleeding and possibly death. The mechanical environment present in AAA is currently thought to be important in disease initiation, progression, and diagnosis. In this study, we utilize porohyperelastic (PHE) finite element models (FEMs) to investigate how such modeling can be used to better understand the local biomechanical environment in AAA. A 3D hypothetical AAA was constructed with a preferential anterior bulge assuming both the intraluminal thrombus (ILT) and the AAA wall act as porous materials. A parametric study was performed to investigate how physiologically meaningful variations in AAA wall and ILT hydraulic permeabilities affect luminal interstitial fluid velocities and wall stresses within an AAA. A corresponding hyperelastic (HE) simulation was also run in order to be able to compare stress values between PHE and HE simulations. The effect of AAA size on local interstitial fluid velocity was also investigated by simulating maximum diameters (5.5 cm, 4.5 cm, and 3.5 cm) at the baseline values of ILT and AAA wall permeability. Finally, a cyclic PHE simulation was utilized to study the variation in local fluid velocities as a result of a physiologic pulsatile blood pressure. While the ILT hydraulic permeability was found to have minimal affect on interstitial velocities, our simulations demonstrated a 28% increase and a 20% decrease in luminal interstitial fluid velocity as a result of a 1 standard deviation increase and decrease in AAA wall hydraulic permeability, respectively. Peak interstitial velocities in all simulations occurred on the luminal surface adjacent to the region of maximum diameter. These values increased with increasing AAA size. PHE simulations resulted in 19.4%, 40.1%, and 81.0% increases in peak maximum principal wall stresses in comparison to HE simulations for maximum diameters of 35 mm, 45 mm, and 55 mm, respectively. The pulsatile AAA PHE FEM demonstrated a complex interstitial fluid velocity field the direction of which alternated in to and out of the luminal layer of the ILT. The biomechanical environment within both the aneurysmal wall and the ILT is involved in AAA pathogenesis and rupture. Assuming these tissues to be porohyperelastic materials may provide additional insight into the complex solid and fluid forces acting on the cells responsible for aneurysmal remodeling and weakening.
Automatic Generation of User Material Subroutines for Biomechanical Growth Analysis
Authors: Young Jonathan M. , Yao Jiang , Ramasubramanian Ashok , Taber Larry A. , Perucchio Renato
Published: August 2010

The analysis of the biomechanics of growth and remodeling in soft tissues requires the formulation of specialized pseudoelastic constitutive relations. The nonlinear finite element analysis package ABAQUS allows the user to implement such specialized material responses through the coding of a user material subroutine called UMAT. However, hand coding UMAT subroutines is a challenge even for simple pseudoelastic materials and requires substantial time to debug and test the code. To resolve this issue, we develop an automatic UMAT code generation procedure for pseudoelastic materials using the symbolic mathematics package MATHEMATICA and extend the UMAT generator to include continuum growth. The performance of the automatically coded UMAT is tested by simulating the stress-stretch response of a material defined by a Fung-orthotropic strain energy function, subject to uniaxial stretching, equibiaxial stretching, and simple shear in ABAQUS. The MATHEMATICA UMAT generator is then extended to include continuum growth by adding a growth subroutine to the automatically generated UMAT. The MATHEMATICA UMAT generator correctly derives the variables required in the UMAT code, quickly providing a ready-to-use UMAT. In turn, the UMAT accurately simulates the pseudoelastic response. In order to test the growth UMAT, we simulate the growth-based bending of a bilayered bar with differing fiber directions in a nongrowing passive layer. The anisotropic passive layer, being topologically tied to the growing isotropic layer, causes the bending bar to twist laterally. The results of simulations demonstrate the validity of the automatically coded UMAT, used in both standardized tests of hyperelastic materials and for a biomechanical growth analysis.
TiN thin film resistors for monolithic microwave integrated circuits
Authors: Malmros Anna , Südow Mattias , Andersson Kristoffer , Rorsman Niklas
Published: August 2010

Titanium nitride (TiN) thin film resistors (TFRs) have been fabricated by reactive sputter deposition. The TFRs were characterized in terms of composition, thickness, and resistance. Furthermore, a first assessment of the resistor reliability was made by measurements of the resistivity (ρ) versus temperature, electrical stress, long-term stability, and thermal infrared measurements. TiN layers with thicknesses up to 3560 Å, corresponding to a sheet resistance (Rs) of 10 Ω/◻, were successfully deposited without any signs of stress in the films. The critical dissipated power (Pc) showed a correlation with the resistor footprint-area indicating that Joule-heating was the main cause of failure. This was partly substantiated by the thermal infrared measurements.
A Unifying Genetic Model for Facioscapulohumeral Muscular Dystrophy
Authors: Lemmers Richard J. L. F. , van der Vliet Patrick J. , Klooster Rinse , Sacconi Sabrina , Camaño Pilar , Dauwerse Johannes G. , Snider Lauren , Straasheijm Kirsten R. , Jan van Ommen Gert , Padberg George W. , Miller Daniel G. , Tapscott Stephen J. , Tawil Rabi , Frants Rune R. , van der Maarel Silvère M.
Published: August 2010

Addition by Contraction

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common hereditary neuromuscular disorders in Western populations, affecting about 1 in 20,000 people. In most patients, the disorder is associated with contraction of a D4Z4 microsatellite repeat array on chromosome 4q, but this contraction can also occur in the absence of disease, so the underlying genetic mechanisms have remained elusive.

Lemmers
et al.

(p.
1650
, published online 19 August; see the Perspective by

Mahadevan

) now show that FSHD patients carry sequence variants that create a canonical polyadenylation signal for transcripts derived from
DUX4
, a homeobox gene straddling the last D4Z4 repeat unit and the adjacent sequence. Addition of poly(A) stabilizes the
DUX4
transcript, which is likely to be a contributing factor in the disease.
A Red-Shifted Chlorophyll
Authors: Chen Min , Schliep Martin , Willows Robert D. , Cai Zheng-Li , Neilan Brett A. , Scheer Hugo
Published: August 2010

Chlorophyll Sees Red

Among the first facts students learn about the natural world is that plants owe their green color to the pigment chlorophyll. There have actually been a handful of slightly different chlorophyll variants uncovered over the years, and

Chen
et al.

(p.
1318
, published online 19 August) have found another in bacteria from Shark Bay, Australia. The chlorophyll variant displayed a red-shifted absorption spectrum, which extended into the near-infrared region due to the insertion of a formyl group on the molecule's periphery. The precise cellular function of the pigment awaits further study.
Tracking Hydrocarbon Plume Transport and Biodegradation at Deepwater Horizon
Authors: Camilli Richard , Reddy Christopher M. , Yoerger Dana R. , Van Mooy Benjamin A. S. , Jakuba Michael V. , Kinsey James C. , McIntyre Cameron P. , Sylva Sean P. , Maloney James V.
Published: August 2010

Diving into Deep Water

The Deepwater Horizon oil spill in the Gulf of Mexico was one of the largest oil spills on record. Its setting at the bottom of the sea floor posed an unanticipated risk as substantial amounts of hydrocarbons leaked into the deepwater column. Three separate cruises identified and sampled deep underwater hydrocarbon plumes that existed in May and June, 2010—before the well head was ultimately sealed.

Camilli
et al.

(p.
201
; published online 19 August) used an automated underwater vehicle to assess the dimensions of a stabilized, diffuse underwater plume of oil that was 22 miles long and estimated the daily quantity of oil released from the well, based on the concentration and dimensions of the plume.

Hazen
et al.

(p.
204
; published online 26 August) also observed an underwater plume at the same depth and found that hydrocarbon-degrading bacteria were enriched in the plume and were breaking down some parts of the oil. Finally,

Valentine
et al.

(p.
208
; published online 16 September) found that natural gas, including propane and ethane, were also present in hydrocarbon plumes. These gases were broken down quickly by bacteria, but primed the system for biodegradation of larger hydrocarbons, including those comprising the leaking crude oil. Differences were observed in dissolved oxygen levels in the plumes (a proxy for bacterial respiration), which may reflect differences in the location of sampling or the aging of the plumes.
Synthesis and selected transformations of 3-oxido-1H-imidazole-4-carboxamides
Authors: Mloston Grzegorz , Jasiński Marcin
Published: August 2010

An efficient synthesis of newN-alkyl- andN-aryl-3-oxido-1H-imidazole-4-carboxamides based on exploration of inexpensive, commercially available ethyl acetoacetate, paraformaldehyde and primary amines is described. Representative compounds were tested in selected transformations, such as ‘sulfur-transfer reaction’ leading to imidazole-2-thiones and isomerization to corresponding imidazol-2-ones. Strong intramolecular hydrogen bonding via theN-oxide function results in the reduced reactivity of 3-oxido-1H-imidazole-4-carboxamides in both reactions. Moreover, the palladium catalyzed C(2)-arylation of imidazole ring as well as azide-alkyne [3+2] cycloaddition using theN-propargyl substituted 4-carboxamide derived from an imidazole 3-oxide as a dipolarophile, were also studied.
Photoluminescence Analysis of Deep Acceptor in CdTe Films on GaAs(100) Substrates
Authors: Onodera Chikara , Yoshida Masaaki , Taguchi Tsunemasa
Published: August 2010

In this study, we used photoluminescence (PL) measurement for analysis of deep acceptor states in unintentionally doped CdTe films on GaAs substrates. We analyzed PL and time-resolved spectra (TRS) in the vicinity of the 1.42 eV band. By analyzing the peak shift of the 1.42 eV band as a function of time after pulsed excitation, the bound-to-bound reaction constant for the unintentionally doped CdTe film on a GaAs substrate is estimated to be W
0=4.0×107 s-1. The impurity concentration in an unintentionally doped CdTe film is estimated to be N=2.1×1016 cm-3. By analyzing the TRS of the 1.42 eV band as a function of time after pulsed excitation, the acceptor binding energy is estimated to be 105 meV. The acceptor binding energy is reasonably comparable to that in the case of a VII-donor-doped CdTe. The acceptor bound exciton, which can probably be attributed to a recombination of excitons bound to a complex acceptor consisting of a Cd vacancy and two Cl donors, is observed. From these features, it appears that the origin of the deep acceptor in unintentionally doped CdTe films on GaAs substrates is a complex acceptor consisting of a Cd vacancy and a Cl donor.
Growth and Optical Properties of Cd1-xZnxS Thin Films
Authors: Zhou Zhen , Zhao Kui , Rockett Angus
Published: August 2010

Highly transparent cadmium zinc sulfide (Cd1-x
Zn
x
S) thin films were deposited by chemical bath deposition (CBD) under various ammonia and thiourea concentrations, which strongly affected the optical properties of Cd1-x
Zn
x
S films at different deposition stages: homogeneous reaction, atom-by-atom process and cluster-by-cluster deposition. Ammonia bound metal ions and, according to complex ion dissociation and equilibrium constants, released small concentration of ions. The hydrolysis of thiourea in the alkaline medium, provided by ammonia hydrolysis, released sulfide ion S2- resulting in the formation of Cd1-x
Zn
x
S thin films. In the CBD deposition process, it was important to control the ions concentration released by these two agents. Otherwise, there would be immediate precipitation or existed a large amount colloids in the reactive bath preventing the deposition of thin films. The influences of various ammonia and thiourea concentrations on the growth mechanism and the optical properties of thin films were investigated. The transmission spectra (TS) and spectra-ellipsometry (SE) were measured and the data were modeled and fitted, giving the parameters which were further to estimate the quality of thin films. The optical properties and the parameters indicated that the ammonia concentration played an important role for obtaining high quality Cd1-x
Zn
x
S films. All parameters showed that it was more essential to control ammonia concentration in CBD deposition of high quality thin films, compared with thiourea.
Tandem Dye-Sensitized Solar Cells Consisting of Nanoporous Titania Sheet
Authors: Uzaki Kenshiro , Pandey Shyam S. , Ogimi Yuhei , Hayase Shuzi
Published: August 2010

Tandem dye-sensitized solar cells consisting of two electrodes in one cell are reported. A tandem cell (Cell TAN GF or Cell TAN St) has a floating electrode (bottom cell) and a TiO2 electrode prepared on a F-doped SnO2 glass substrate (top cell). The floating electrode is a flexible and self-standing composite film consisting of a porous titania/dye layer supported by a glass mesh sheet or a stainless-steel mesh sheet. The incident photon-to-current conversion efficiency (IPCE) curves for Cell TAN GF and Cell TAN St had two peaks corresponding to the visible absorption of the two dyes. The open circuit voltages (V
oc) of Cell TAN GF and Cell TAN St were 0.82 and 0.88 V, respectively, which were higher than that of the corresponding single cell (0.6–0.64 V). These results demonstrated that both Cell TAN GF and Cell TAN St can be used as tandem cells. The fact that the V
oc of Cell TAN GF is almost the same as that of Cell TAN St leads to the conclusion that a conductive layer is not necessarily needed for the bottom electrode.
A Tunable-Transmission Sagnac Interferometer Using an Optical Microfiber
Authors: Lim Sun Do , Lee Sun-Goo , Lee Kwanil , Lee Sang Bae
Published: August 2010

This paper deals with fabrication of an optical microfiber and demonstration of a Sagnac loop interferometer constructed with it. An optical microfiber with a diameter ∼2 µm and loss ∼0.03 dB/mm is manufactured by tapering a conventional single-mode fiber using a flame-brushing technique. A Sagnac interferometer is assembled by twisting the fabricated microfiber into a loop. The intertwisted section of the loop functions as a directional coupler whose coupling ratio is tunable by changing the twist rate. Transmission characteristics of the interferometer may allow us to use it as a potential photonic device such as a linear edge filter, an optical variable attenuator, or a gain flattening filter.
Effect of Additives on Absorption Edge Energy in Bismuth Phosphate Glass
Authors: Kitamura Naoyuki , Ohno Kentarou , Fukumi Kohei , Nakamura Junichi , Hidaka Tatsuo , Ikeda Takurou , Hashima Hidekazu , Kozuka Hiromitsu , Nishii Junji
Published: August 2010

The effect of third-additive oxides on absorption edge energy was studied in binary bismuth phosphate glass. The edge energy was shifted toward lower energies by the substitution of third-additive oxides for P2O5. The substitutions of glass-network-forming (NWF) oxides and glass-network-modifying (NWM) oxides resulted in distinct linear relationships between the edge energy and Duffy's ideal basicity. The energy shift against the calculated basicity was larger for the substitution of NWF oxides than for that of NWM oxides. Moreover, the substitution of intermediate oxides gave a similar tendency to the substitution of NWF oxides rather than to that of NWM oxides for both relationships. It was deduced that electron donation is more sensitive to the substitution of NWF oxides than to that of NWM oxides. On the other hand, a 238 cm-1 Raman band, which is attributed to the Bi–O vibration mode, shifted toward higher wave numbers by the substitution of all of the oxides. The 238 cm-1 band showed a linear relationship with the ideal basicity similar to the relationship between the edge energy and the basicity. Sensitivity against electron donation was consistent with both the Bi–O bond strength and the absorption edge energy.
Fabrication of Highly Scaled Silicon Nanowire Gate-All-Around Metal–Oxide–Semiconductor Field Effect Transistors by Using Self-Aligned Local-Channel V-gate by Optical Lithography Process
Authors: Park Jae Hyun , Song Jae Young , Kim Jong Pil , Kim Sang Wan , Yun Jang-Gn , Park Byung-Gook
Published: August 2010

The silicon nanowire gate-all-around (GAA) metal–oxide–semiconductor field effect transistors (MOSFETs) have been fabricated by using inverted sidewall spacers to scale the gate length. The patterning strategy of inverted sidewall spacers is based on the self-aligned local-channel V-shaped gate electrode (V-gate) by optical lithography (SALVO) process. Through this technique, we have obtained an aggressively scaled gate length down to 10 nm regime. In addition, the silicon nanowire structure with diameter of about 10 nm has been successfully formed by reducing of the local channel. In the fabricated device, we have confirmed that it has excellent device characteristics in terms of the sub-threshold swing (SS), drain induced barrier lowering (DIBL), and low level of off-state leakage current in spite of the short-channel effect (SCE).
Program/Erase Model of Nitride-Based NAND-Type Charge Trap Flash Memories
Authors: Kim Doo-Hyun , Cho Seongjae , Li Dong Hua , Yun Jang-Gn , Lee Jung Hoon , Lee Gil Sung , Kim Yoon , Shim Won Bo , Park Se Hwan , Kim Wandong , Shin Hyungcheol , Park Byung-Gook
Published: August 2010

In this paper, we present a detailed study of the physical dynamics of the program/erase (P/E) operations in nitride-based NAND-type charge trapping silicon–oxide–nitride–oxide–silicon (SONOS) flash memories. By calculating the internal oxide fields, tunneling currents, and trapping charges, we evaluated the simple charge trapping mechanism. We calculated transient P/E threshold voltage (V
T) shift considering the ONO fields and tunneling currents. All the parameters were obtained using totally physics-based equations with no fitting parameters or optimization steps. The results show conventional NAND SONOS flash memory P/E characteristics in the Fowler–Nordheim (FN) operation regime. Also, these P/E simulation results agree with the measurement data of 30×70 nm2 (L×W) SONOS flash memory devices that have 2.3/12/4.5 and 3/9/7 nm ONO stack layers. This model fully accounts for the V
T shift as a function of the applied gate voltage, transient time, and thicknesses of silicon oxide and silicon nitride layers, which can be used for optimizing the ONO thicknesses and the parameters for improving performance.
Thermo-Optical Properties of Colloids Enhanced by Gold Nanoparticles
Authors: Aleali Hoda , Sarkhosh Leila , Eslamifar Mina , Karimzadeh Rouhollah , Mansour Nastaran
Published: August 2010

This work presents a study on the thermo-optical properties of colloidal gold nanoparticles (AuNPs) under a low power laser irradiation at 532 nm. Samples of various gold volume fractions, ranging from 2.5×10-4 to 19.5×10-4%, are synthesized by nanosecond pulsed laser ablation of a pure gold plate in the distilled water. The formation of the AuNPs has been evidenced by optical absorption spectra and transmission electron microscopy. We investigate the effect of the gold nanoparticle concentration on thermo-optical properties of the colloids using the Z-scan technique. The nonlinear optical measurements exhibit a very large nonlinear refraction close to the surface plasmon resonance frequency of the nanoparticles. Our results reveal that the heat diffusion in the colloids is due to nonlocal thermal process. As the gold concentration increases, the temperature change within and around gold nanoparticles greatly enlarges the thermo-optic and thermal nonlinear refractive index coefficients of the samples. This work suggests that thermal nonlinear refraction will play an important role in development of photonic applications involving metal nanoparticles colloids.
Zinc Oxide-Based Schottky Diode Prepared Using Radio-Frequency Magnetron Cosputtering System
Authors: Lai Bo-Ting , Lee Ching-Ting , Hong Jhen-Dong , Yao Shiau-Lu , Liu Day-Shan
Published: August 2010

The rectifying property of a zinc oxide (ZnO)-based Schottky diode prepared using a radio-frequency (rf) magnetron cosputtering system was improved by enhancing the cosputtered ZnO crystal quality, thereby optimizing the ohmic contact resistance and compensating the Schottky contact surface states. An undoped ZnO layer with a high c-axis orientation and a low internal residual stress was achieved using a postannealing treatment. A homogeneous n-type ZnO–indium tin oxide (ITO) cosputtered film was deposited onto the undoped ZnO layer to optimize the ohmic contact behavior to the Al electrode. The Schottky contact surface of the undoped ZnO layer to the Ni/Au electrode was passivated using an oxygen plasma treatment. Owing to the compensation of the native oxygen vacancies (VO) on the undoped ZnO surface, the leakage current markedly decreased and subsequently led to a quality Schottky diode performance with an ideality factor of 1.23 and a Schottky barrier height of 0.82 eV.
Growth Kinetics and Properties of Thin Cobalt Films Electrodeposited on n-Si(100)
Authors: Lee Jong Duk , An Tae Hwan , Noh Hak Gi , Kim Sung Gon , Choi Young R.
Published: August 2010

The cobalt thin films were directly grown on n-Si(100) substrates in a non-aqueous electrolyte of 0.1 M CoCl2 by using pulsed electrodeposition technique. In this paper, the growth, structural and magnetic properties of thin Co films have been investigated. Current transient experiments showed that Co nuclei in the early deposition stage forms through three dimensional (3D) instantaneous nucleation followed by diffusion-limited growth. From the atomic force microscopy (AFM) analysis, it has been found that the film surface consisted of cubic and distorted rectangular-shaped nanocrystallites with the average size of about 140 nm irrespective of the deposition voltage. X-ray diffraction (XRD) measurement indicated that Co was arranged with only a hexagonal close-packed (hcp) structure not involving face-centered cubic (fcc) Co or silicide phases. Vibrating sample magnetometer (VSM) measurements revealed that the easy magnetization axis of Co thin film is parallel to the film plane.
Numerical Simulation of Electron Transport in Electric and Magnetic Fields for Analysis of Electron Temperature and Number Density Profiles Measured in Argon Magnetic Neutral Loop Discharge Plasma
Authors: Sugawara Hirotake , Osaga Tsuyoshi , Tsuboi Hideo , Kuwahara Kiyoshi , Ogata Seiji
Published: August 2010

A Monte Carlo simulation of electron transport in electric and magnetic fields was performed to analyze experimental data of the electron temperatureTeand electron number densitynemeasured in a magnetic neutral loop discharge (NLD) plasma driven in Ar at 0.13 Pa.Teandnein the vicinity of the substrate holder were measured with a triple probe, and their radial profiles had peaks at different radial positions. The simulation reproduced these peak positions well under the chosen boundary condition that the electron reflectivity of the side wall was lower than that of the reactor ceiling and the substrate holder. It was explained that theTepeak was formed by high-energy electrons transported from the neutral loop along a separatrix of the quadrupole magnetic field and that thenepeak consisted of electrons undergoing reciprocating motion between the reactor ceiling and the substrate.
Novel Antenna Coupler Design for Production of Meter-Scale High-Density Planar Surface Wave Plasma
Authors: Ishijima Tatsuo , Nojiri Yasunori , Toyoda Hirotaka , Sugai Hideo
Published: August 2010

A vacuum-sealed antenna coupler was newly developed for excitation of meter-scale high-density surface wave plasma for manufacturing giant microelectronics devices such as liquid crystal displays and thin-film solar cells. To produce large-area uniform plasma, various multislot antenna designs at 2.45 GHz were investigated by slot antenna analysis and simulation using the finite difference time domain (FDTD) method. Optical emission images of the plasma observed using a wide-angle charge-coupled device (CCD) camera and Langmuir probe measurements revealed the production of a very uniform and high-density plasma of 1 m length and 0.3 m width whose dimensions can easily be expanded to a much larger scale. Furthermore, the production of a large-area sheetlike plasma of 2 cm thickness and 1 m length has been demonstrated to reduce the discharge power, heat load, gas consumption, and pumping load.
Effects of Wafer Precleaning and Plasma Irradiation to Wafer Surfaces on Plasma-Assisted Surface-Activated Direct Bonding
Authors: Takei Ryohei , Yoshida Kohei , Mizumoto Tetsuya
Published: August 2010

The plasma-assisted surface-activated bonding technique enables one to directly bond heterogeneous materials. The surface roughness of wafers is an important factor for achieving bonding. The effects of precleaning and plasma surface activation processes on the surface roughness are investigated for silicon-on-insulator (SOI), Ce-substituted yttrium iron garnet (Ce:YIG), InP and LiNbO3. We found that an appropriate precleaning process reduces the surface roughness. Also, the oxygen plasma irradiation to the wafer surface for 10 or 30 s smoothens the surfaces. We achieved the bonding of SOI–Ce:YIG with a strength greater than 1.8 MPa, which is sufficient for application to silicon waveguide optical isolators and circulators.
Reduction of Multipole Fields in Photocathode RF Gun
Authors: Moon Sungik , Hong Juho , Parc Yongwoon , Cho Moohyun , Namkung Won , Ko In Soo , Park Sung-Ju
Published: August 2010

Photocathode rf gun, the high-brightness electron source with extremely low emittance is highly required for future light sources such as X-ray free electron lasers (XFEL). The coupling hole between the waveguide and the cavity of a photocathode rf gun causes asymmetries in the rf fields at the coupler cell. The dipole and quadruple fields are the dominant sources of the transverse rf emittance growth. In the BNL Gun-III, the dipole field is reduced by adding a symmetric pumping hole at the opposite side of the waveguide coupling hole. The dipole field can be reduced further by adjusting the size of the pumping hole. However, the quadruple field cannot be suppressed by the single pumping hole. We have designed new rf cavity in which the quadruple field as well as the dipole one are suppressed. In this design, two additional pumping ports are placed at the 90° positions with respect to the coupling hole and the pumping holes. Beam dynamics simulation for newly designed rf gun shows that the vertical transverse emittance is reduced by about 60% compared to the old one.
Effect of Complex Agent on Characteristics of Copper Conductive Pattern Formed by Ink-jet Printing
Authors: Lee Young-In , Lee Kun-Jae , Goo Yong-Sung , Kim Nam-Woo , Byun Younghoon , Kim Joong-Do , Yoo Bongyoung , Choa Yong-Ho
Published: August 2010

In this study, Cu ion complex ink was successfully synthesized by a modified electrolysis method in which the Cu ions generated from bulk metal plates by an electric field were coordinated with complex agents. The synthesized ink was ink-jet-printed on a flexible substrate and converted to a dense Cu pattern after sintering at 250 °C. The pattern was characterized by X-ray diffractometry, field emission scanning electron microscope, and four-point probe method to confirm the crystal structure, microstructure, and electrical conductivity, respectively. The effect of the type of complex agent on the characteristics of a Cu conductive pattern was also determined using the analysis results. Finally, we conducted the direct writing of conductive dots and lines using the Cu ion complex ink, and confirmed that fine patterning for application in electronics is possible with the Cu ion complex ink.
Mass Markers for Time-of-Flight Secondary Ion Mass Spectrometry Spectrum in a Large Mass Region Using Ir4(CO)12 Metal Cluster Complex Sample
Authors: Nonaka Hidehiko , Nakanaga Taisuke , Fujiwara Yukio , Saito Naoaki , Fujimoto Toshiyuki
Published: August 2010

The time-of-flight secondary ion mass spectrometry (TOF-SIMS) spectra of a metal cluster complex, Ir4(CO)12, evaporated on a Si wafer have been analyzed to clarify the origin of the mass deviation of the peaks from the true mass positions expected from the m/z values. Most of the peaks in the TOF-SIMS spectra are found to show shifts from the true positions due to the dissociation of secondary ions, i.e., release of a CO ligand, after the ionization. In conclusion, the ion peaks that can be used as mass markers of the TOF-SIMS system must be stable parent ions; such peaks are those assigned to Ir4(CO)12
+ (m/z 1,100–1,108) and Ir5(CO)14
+ (m/z 1,347–1,357) for positive ions, and Ir4(CO)11
- (m/z 1,072–1,080), Ir5(CO)13
- (m/z 1,319–1,329), and Ir8(CO)22
- (m/z 2,144–2,160) for negative ions with 10–50 ppm precision.
Production of Nanoparticles Using Several Materials for Labeling of Biological Molecules
Authors: Kim Hyonchol , Takei Hiroyuki , Yasuda Kenji
Published: August 2010

Various size-controlled metal nanoparticles (NPs) coated with probe DNAs have been developed. Gold, silver, germanium, copper, or nickel was thermally deposited as the inner layer on the surface of a polystyrene bead, and gold was coated as the outer layer for immobilizing thiolated probe DNAs by Au–S covalent bonding. The ultraviolet–visible (UV–vis) spectra of NPs showed that an outer gold layer thickness of 2 nm was sufficient for the immobilization of probe DNAs having a signal/noise (S/N) ratio of specific attachment of NP probes on the DNA chips eight-times higher than that of fluorescent probes. The size distributions of NPs were within the 6.7% coefficient of variation regardless of the type of metal and size. The different metal layers of NPs were also discriminated successfully by measuring backscattered electron intensity by scanning electron microscopy (SEM). The results indicate that NPs can be used for a two-dimensional probe set for SEM observation of size differences and differences in the type of metal used.
EuCl2 Powder as a Pressure-Memory Material
Authors: Kobayashi Takamichi
Published: August 2010

By utilizing the effect of an unusually large residual stress on the photoluminescence spectra of EuCl2 powder, we found that the EuCl2 powder appears to have potential as a pressure-sensor material for cases where in situ pressure measurements are difficult. The applicable pressure range is roughly 0–1.3 GPa. The photoluminescence peak position of the EuCl2 powder is significantly redshifted after the EuCl2 powder has experienced pressure; in other words, the maximum pressure the powder has experienced is reflected in the luminescence peak shift of the recovered powder. Some technical points for using the EuCl2 powder as a pressure-sensor material are also discussed.
Inductively Coupled Plasma Reactive Ion Etching of Gallium Indium Zinc Oxide Thin Films Using Cl2/Ar Gas Mix
Authors: Xiao Yu Bin , Kim Eun Ho , Kong Seon Mi , Chung Chee Won
Published: August 2010

Inductively coupled plasma reactive ion etching of gallium indium zinc oxide (GIZO) thin films patterned with a photoresist was studied using a Cl2/Ar gas. As the Cl2 concentration was increased from pure Ar to 40% Cl2 concentration, the etch rate of GIZO films increased, and thereafter gradually decreased. The etch rate increased with increasing coil rf power and dc bias voltage. A high degree of anisotropy was achieved with increasing coil rf power and dc-bias voltage, and decreasing gas pressure. X-ray photoelectron spectroscopy of the etched films revealed that chemical compounds were formed during the etching process, indicating that the etching of GIZO films is governed by a reactive ion etching mechanism.
Investigation of Mask Inclination Due to Oxygen-Radical Irradiation during Resist Trimming
Authors: Kofuji Naoyuki , Miura Hideo
Published: August 2010

A novel analytical method for predicting the inclination of a resist mask during its trimming process has been proposed by considering the formation of the surface degraded layer with high compressive stress. It was found that the irradiation of oxygen radicals creates a degraded layer on the resist surface and causes high compressive stress in it. A nonuniform spatial distribution of oxygen radicals, therefore, causes an asymmetrical stress field on the resist-mask surface. Such an asymmetrical stress field distorts the resist mask. The well-known Deal–Grove's oxidation model was modified for the trimming process by considering the time-dependent change of the spatial distribution of oxygen radicals on the mask surface. This model successfully explains the observed complicated time-dependent deformation of the resist mask.
Optical and Electrical Characterization of Hydrogen-Plasma-Damaged Silicon Surface Structures and Its Impact on In-line Monitoring
Authors: Nakakubo Yoshinori , Matsuda Asahiko , Fukasawa Masanaga , Takao Yoshinori , Tatsumi Tetsuya , Eriguchi Koji , Ono Kouichi
Published: August 2010

Si surface damage induced by H2plasmas was studied in detail by optical and electrical analyses. Spectroscopic ellipsometry (SE) revealed a decrease in the pseudo-extinction coefficient <κ> in the region of photon energy higher than ∼3.4 eV upon H2-plasma exposure, which is attributed to the disordering of crystalline silicon (c-Si). The increase in <κ> in the lower energy region indicates the presence of trap sites for photogenerated carriers in the energy band gap in theE–kspace of Si. The current–voltage (I–V) measurement of metal-contacted structures was performed, revealing the following characteristic structures: thinner surface (SiO2) and thicker interface (SiO2:c-Si) layers on the Si substrate in the case of H2-plasma exposure than those with Ar- and/or O2-plasma exposure. The structure assigned on the basis of both SE andI–Vwas further analyzed by a layer-by-layer wet-etching technique focusing on the removability of SiO2and its etch rate. The residual damage-layer thickness for the H2-plasma process was thicker (∼10 nm) than those for other plasma processes (<2 nm). Since the interface layer plays an important role in the optical assessment of the plasma-damage layer, the present findings imply that a conventional two-layer (SiO2/Si) optical model should be revised for in-line monitoring of H2-plasma damage.
Chemical Sputtering of GaN Crystal with a Chlorine-Adsorbed Layer
Authors: Harafuji Kenji , Kawamura Katsuyuki
Published: August 2010

A molecular dynamics simulation has been carried out to investigate the chemical sputtering of wurtzite-type GaN(0001) surfaces with and without a Cl-adsorbed layer. Sputtering of crystalline atoms is examined with Ar impacts at energies less than 250 eV. Ga sputtering does not take place at all on the clean surface without Cl-adsorption. On the other hand, Ga sputtering yield has a large finite value for Ar impact on the Cl-adsorbed surface. Generally, Ga is sputtered in the form of Ga–Cl2, and sometimes in the form of Ga–Cl, Ga–N–Cl, Ga–N, and Ga–N–Ga–Cl2. Ga atoms are not singly sputtered. Atoms escape from the surface in the time range of 200–3000 fs after the impact of the incident Ar atom. The shorter and longer escape times correspond to physical and chemical sputtering, respectively.
Amorphous Indium Gallium Zinc Oxide Semiconductor Thin Film Transistors Using O2 Plasma Treatment on the SiNx Gate Insulator
Authors: Kim Woong-Sun , Moon Yeon-Keon , Lee Sih , Kang Byung-Woo , Kim Kyung-Taek , Lee Je-Hun , Kim Joo-Han , Ahn Byung-Du , Park Jong-Wan
Published: August 2010

In this study, we investigated the role of processing parameters on the electrical characteristics of amorphous In–Ga–Zn–O (a-IGZO) thin film transistors (TFTs) fabricated using DC magnetron sputtering at room temperature. Processing parameters including the oxygen partial pressure, annealing temperature, and channel thickness have a great influence on TFT performance and better devices are obtained at a low oxygen partial pressure, annealing at 200 °C, and a low channel thickness. We attempted to improve the a-IGZO TFT performance and stability under a gate bias stress using O2 plasma treatment. With an O2 plasma treated gate insulator, remarkable properties including excellent bias stability as well as a field effect mobility (µFE) of 11.5 cm2 V-1 s-1, a subthreshold swing (S) of 0.59 V/decade, a turn-on voltage (V
ON) of -1.3 V, and an on/off current ratio (I
ON/I
OFF) of 105 were achieved.
Modified Julolidine-Containing Emitters for Red Organic Light-Emitting Diodes
Authors: Lee Kum Hee , Park Min Hye , Kim Sung Min , Kim Young Kwan , Yoon Seung Soo
Published: August 2010

The compounds 2.1.1-(2-(4-pentylbicyclo[2.2.2]octan-1-yl)-6-(2-(1,1,7,7-tetramethyl-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)vinyl)-4H-pyran-4-ylidene)malononitrile (Red 1) and 2-(2-(2-(1,1-dimethyl-7,7-bis((trimethylsilylmethyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)vinyl)-6-(4-pentylbicyclo[2.2.2]octan-1-yl)-4H-pyran-4-ylidene)malononitrile (Red 2) with modified julolidine moieties were developed and synthesized. To determine the electroluminescence properties of these materials, multilayered organic light-emitting diodes (OLEDs) were fabricated with a device structure of indium tin oxide (ITO)/N,N'-diphenyl-N,N'-(1-napthyl)-(1,1'-phenyl)-4,4'-diamine (50 nm)/tris(8-quinolinolato)-aluminum (Alq3):dopants Red 1 and Red 2 (30 nm, 1–5%)/Alq3(50 nm)/8-hydroxyquinolatolithium (2 nm)/Al. All devices exhibited efficient red emission. In particular, a device using Red 2 as the dopant material showed a maximum luminance of 1455 cd/m2at 12.0 V, and maximum luminous and power efficiencies of 1.71 cd/A and 1.32 lm/W, respectively. The Commission Internationale de l'Eclairage coordinates of this device were (0.64,0.36) at 7.0 V, which indicated stable color chromaticity at various voltages.
Titanium Oxide Thin Films Prepared by Plasma Enhanced Atomic Layer Deposition Using Remote Electron Cyclotron Resonance Plasma for Organic Devices Passivation
Authors: Kang Byung-Woo , Kim Woong-Sun , Hwang Chang-Mook , Moon Dae-Yong , Kim Jay-Jung , Park Jae-Gun , Park Jong-Wan
Published: August 2010

We examined titanium oxide films and their barrier characteristics. Titanium oxide films were deposited at room temperature with electron cyclotron resonance plasma power of 300 W. We measured the growth rate of the titanium oxide film to be 1.8 Å/cycle. Barrier layers on poly(ether sulfon) (PES) substrates were observed to provide activation energy for water permeation. Activation energy of 12.4 kJ/mol was added by applying a titanium oxide coating with a thickness of 100 nm. The passivation performance of the titanium oxide film was also investigated using organic light-emitting diodes (OLEDs). The relative luminance of a 400-nm-thick-coated OLED device was diminished by 11.6% for 20 h.
Electrochemical Characterization of O2 Plasma Functionalized Multi-Walled Carbon Nanotube Electrode for Legionella pneumophila DNA Sensor
Authors: Park Eun Jin , Lee Jun-Yong , Kim Jun Hyup , Kim Sun Kug , Lee Cheol Jin , Min Nam Ki
Published: August 2010

An electrochemical DNA sensor for Legionella pneumophila detection was constructed using O2 plasma functionalized multi-walled carbon nanotube (MWCNT) film as a working electrode (WE). The cyclic voltammetry (CV) results revealed that the electrocatalytic activity of plasma functionalized MWCNT (pf-MWCNT) significantly changed depending on O2 plasma treatment time due to some oxygen containing functional groups on the pf-MWCNT surface. Scanning electron microscope (SEM) images and X-ray photoelectron spectroscopy (XPS) spectra were also presented the changes of their surface morphologies and oxygen composition before and after plasma treatment. From a comparison study, it was found that the pf-MWCNT WEs had higher electrocatalytic activity and more capability of probe DNA immobilization: therefore, electrochemical signal changes by probe DNA immobilization and hybridization on pf-MWCNT WEs were larger than on Au WEs. The pf-MWCNT based DNA sensor was able to detect a concentration range of 10 pM–100 nM of target DNA to detect L. pneumophila.
Formation of High-Quality SiO2 and SiO2/Si Interface by Thermal-Plasma-Jet-Induced Millisecond Annealing and Postmetallization Annealing
Authors: Hiroshige Yasuo , Higashi Seiichiro , Matsumoto Kazuya , Miyazaki Seiichi
Published: August 2010

For the formation of a high-quality SiO2 and SiO2/Si interface, we have applied thermal-plasma-jet (TPJ)-induced millisecond annealing to SiO2 films deposited at 300 °C by plasma-enhanced chemical vapor deposition (PECVD). By TPJ annealing at 1088 K for 2.8 ms, the amount of Si–OH bond groups decreased significantly and an increase in the amount of Si–O–Si bond groups was observed. This result suggests that the desorption of H2O and the cross linkage of Si–O–Si are promoted, and the densification of SiO2 films is achieved. By performing TPJ annealing followed by postmetallization annealing (PMA), a high-quality SiO2/Si interface with a trap density (D
it) of 3.0×1010 cm-2 eV-1 was achieved. In addition, TPJ-annealed SiO2 films show a higher durability under a constant current stress than SiO2 films prepared only by PMA. This is attributed to the improvement of the bulk chemical bond network of SiO2 films by TPJ annealing. These results indicate that the combination of TPJ and PMA is one of the promising low-temperature processes for the long-term reliability of SiO2 films and the formation of a high-quality SiO2 and SiO2/Si interface.
Localized Etching of a Polyimide Film by an Atmospheric-Pressure Radio Frequency Microplasma Excited by a 100-µm-φ Metal Pipe Electrode
Authors: Yoshiki Hiroyuki
Published: August 2010

Atmospheric-pressure He and Ar microplasmas (µ-plasmas) have been generated by a 14 MHz radio-frequency (RF) discharge using a metal narrow pipe electrode with an outer diameter of 100 µm. The metal pipe acts as both a powered electrode and a gas nozzle. The discharge mode changed from a corona discharge to a glow discharge and finally to a thermal spot arc discharge with decreasing discharge gap between the pipe electrode and the grounded plate as well as with increasing RF power. The Ar glow µ-plasma was applied to the localized etching of a polyimide film with a thickness of 0.025 mm in air ambient. The etched spot showed an isotropic profile having a gradual slope with a full width at half maximum of approximately 170 µm. The etching rate was approximately 3 µm/s at an RF power of 1.5 W. The optical emission spectrum exhibited second-positive N2 molecular bands and atomic oxygen lines (777 and 845 nm) as well as many Ar atomic lines. It appears that the energetic N2 molecules and UV photons radiated from the excitation states of N2 broke C–C and C–H bonds and then O radicals reacted with the hydrocarbon fragments to produce CO2 and H2O. Consequently, isotropic chemical etching was achieved.
Beveling of Silicon Carbide Wafer by Plasma Etching Using Atmospheric-Pressure Plasma
Authors: Sano Yasuhisa , Kato Takehiro , Yamamura Kazuya , Mimura Hidekazu , Matsuyama Satoshi , Yamauchi Kazuto
Published: August 2010

Although beveling is essential for preventing the chipping of particles from the edge of a wafer during surface polishing, there is no high-efficiency beveling method for a silicon carbide wafer because of its hardness and chemical inertness. Thus, in this study, plasma etching using atmospheric-pressure plasma is applied for the beveling of a silicon carbide wafer. As a result, an initially square corner was well rounded within 20–30 min. The beveling rate was highest at the start of processing and decreased with increasing radius of curvature. It was proven that the beveling phenomenon was due to the electric-field concentration at the edge of the wafer as determined by calculating electric-field intensity.
Modulation Code and Signal Characteristics for Signal Waveform Modulation Optical Disc
Authors: Liu Hailong , Pei Jing , Pan Longfa , Ni Yi
Published: August 2010

A high-efficient and novel varying-level multilevel run-length-limited modulation code is proposed for signal waveform modulation (SWM) optical discs. The proposed code is composed of a maximum transition run (MTR) code and a level modulation process. The MTR code is employed to realize high code rate and satisfy the requirements of channels. Level modulation is used to eliminate inappropriate codewords for SWM channels and determine the level numbers for different runs. The rate of the presented code is 7/8 bits/symbols, and the recording density parameter RBPF (recording bits per 400 nm) is 2.26, which is 50.7% more than that of a digital versatile disc (DVD). The realization of the proposed code in SWM discs and the corresponding signal characteristics are also shown. With the run-length detection and level detection solution, the bit error rate (BER) is less than 2×10-4, which is feasible for SWM multilevel optical discs.
Holographic Read-Only Memory Fabricated by Deposition of Reflector after Writing Process with Aromatic Photopolymer Recording Layer
Authors: Ando Toshio , Masaki Kazuyoshi , Shimizu Takehiro
Published: August 2010

The deposition of reflector after writing (DRAW) process has been proposed for the fabrication of reflective-type holographic read-only memories. In the DRAW process, a reflector is deposited on a recording medium after signal writing, resulting in the reduction of noise holograms written by reflected beams from a reflector in the write process. Significant improvements are experimentally confirmed in read and write (R/W) performances in DRAW-processed holographic media. The combination of the DRAW process and an aromatic photopolymer recording material realizes low noise, high signal-to-noise ratio, and low symbol error rate characteristics at large multiplexing numbers up to 1020. In conventional reflective-type holographic media, ghost noise is superimposed on the readout signal, causing deterioration in R/W characteristics. The wave vector analyses clarify the mechanism by which the noise holograms are written and ghost noise is superimposed on the signal beam in the conventional media.
Compensation of Interference Fringe Distortion Due to Temperature Variation in Holographic Data Storage
Authors: Muroi Tetsuhiko , Kinoshita Nobuhiro , Ishii Norihiko , Kamijo Koji , Shimidzu Naoki
Published: August 2010

Photopolymer materials are feasible for holographic recording media. However, these materials shrink owing to photopolymerization and interference fringes recorded in them distort. In addition, temperature variation causes shrinkage and expansion of these materials and thus distorts recorded interference fringes. This distortion degrades reconstructed image quality and decreases the signal-to-noise ratio of the reproduced data. We applied adaptive optics controlled by a genetic algorithm to compensate for the distortion and improved the reconstructed image quality at 25 and 30 °C ambient temperature. Under these conditions, the signal-to-noise ratio of reproduced data was more than 4 dB. Furthermore, we evaluated the distortion due to the temperature variation by using a medium angle and the wavefront of the reference beam. We found that the distortion caused by anisotropic shrinkage is slight; consequently, an optimised wavefront at 25 °C can compensate for the interference fringe distortion and increase the signal-to-noise ratio by adjusting only the medium angle even if a temperature variation occurs. Adaptive optics can thus be used to compensate for interference fringe distortion caused by shrinkage and expansion due to temperature variation.