bluuebunny/crossref_metadata_2025 huggingface dataset:
The Horizon Homeopathic Dilution Experiment
Authors: Bland Martin
Published: September 2005

In 2002 Martin Bland made his first appearance on television, in a BBC2 Horizon programme on homeopathy. When he gives talks about this work, the list of acknowledgements includes John Enderby, Vice-President of the Royal Society, and James Randi, magician. It's not every research team that includes a magician!
Latin Squares and Su Doku
Authors: Freeman Geoff
Published: September 2005

Latin squares have been around for a long time—more than 200 years—while su doku is a modern invention. However, as Geoff Freeman points out, the two have a great deal in common.
Neighbourhood Watch: Population Forecasting for New Housing Developments
Authors: Garcia Paul
Published: September 2005

In 2003 Paul Garcia was awarded a Royal Statistical Society Campion Fellowship, with a grant of £5000, to carry out a study to try to determine the age profile of residents of new housing developments and explain how that profile changes over time. He describes why he wanted to do the work and how he set about organising the survey.
How to Take a Penalty
Authors: Eastaway Rob
Published: September 2005

When Rob Eastaway told friends he was embarking on a project to write a book about the maths of sport, they didn't hear the word “maths”—they heard “statistics”. That, after all, is the most obvious interpretation. But, as he discovered, mechanics, geometry and even some mathematical history all play their part …
Five Quantitative Physics Experiments (Almost) Without Special Apparatus
Authors: Hunt James L.
Published: September 2005

There are situations in which physics students would profit from the performance of real quantitative experiments but the equipment is lacking, expensive, or too bulky. One such situatuation is in distance education courses, where the desire to have students perform real experiments is outweighed by cost and/or logistics. The result often is a resort to simulated experiments, or incurring the expense of bringing students to a central location for a marathon session of lab exercises, many of which are done out of sequence. I describe here five quantitative experiments designed for an introductory DE course in physics, that require almost nothing in the way of equipment except a computer and items commonly found in the home.
A Demonstration of the Critical Angle Without Using Total Internal Reflection
Authors: Viss Barret R. , Sikkema Arnold E.
Published: September 2005

The success of a light ray's transmission to a medium of lower index of refraction depends upon its incident angle at the boundary. If this angle, when measured from the normal, is greater than a certain critical angle, the ray will reflect totally, remaining in the high-index medium. Snell's law, which says that n1 sin θ1 = n2 sin θ2, easily gives the critical angle as θ1 = sin−1(n2/n1) by setting the angle of refraction to θ2 = 90°. Demonstrations of the critical angle phenomenon usually work with this operational definition. For example, as in Fig. 1, one directs a beam of light radially through the curved surface of a semicircular piece of glass and rotates the semicircle until no ray is seen exiting the flat surface. We describe here a demonstration of the critical angle that does not employ rays leaving the higher-index medium but entering it.
The Origin of Planetary Impactors in the Inner Solar System
Authors: Strom Robert G. , Malhotra Renu , Ito Takashi , Yoshida Fumi , Kring David A.
Published: September 2005

Insights into the history of the inner solar system can be derived from the impact cratering record of the Moon, Mars, Venus, and Mercury and from the size distributions of asteroid populations. Old craters from a unique period of heavy bombardment that ended ∼3.8 billion years ago were made by asteroids that were dynamically ejected from the main asteroid belt, possibly due to the orbital migration of the giant planets. The impactors of the past ∼3.8 billion years have a size distribution quite different from that of the main belt asteroids but very similar to that of near-Earth asteroids.
Stability of EcoRI Restriction-Modification Enzymes In Vivo Differentiates the EcoRI Restriction-Modification System from Other Postsegregational Cell Killing Systems
Authors: Ichige Asao , Kobayashi Ichizo
Published: September 2005

Certain type II restriction modification gene systems can kill host cells when these gene systems are eliminated from the host cells. Such ability to cause postsegregational killing of host cells is the feature of bacterial addiction modules, each of which consists of toxin and antitoxin genes. With these addiction modules, the differential stability of toxin and antitoxin molecules in cells plays an essential role in the execution of postsegregational killing. We here examined in vivo stability of the EcoRI restriction enzyme (toxin) and modification enzyme (antitoxin), the gene system of which has previously been shown to cause postsegregational host killing in
Escherichia coli
. Using two different methods, namely, quantitative Western blot analysis and pulse-chase immunoprecipitation analysis, we demonstrated that both the EcoRI restriction enzyme and modification enzyme are as stable as bulk cellular proteins and that there is no marked difference in their stability. The numbers of EcoRI restriction and modification enzyme molecules present in a host cell during the steady-state growth were estimated. We monitored changes in cellular levels of the EcoRI restriction and modification enzymes during the postsegregational killing. Results from these analyses together suggest that the EcoRI gene system does not rely on differential stability between the toxin and the antitoxin molecules for execution of postsegregational cell killing. Our results provide insights into the mechanism of postsegregational killing by restriction-modification systems, which seems to be distinct from mechanisms of postsegregational killing by other bacterial addiction modules.
Periplasmic Domains Define Holin-Antiholin Interactions in T4 Lysis Inhibition
Authors: Tran Tram Anh T. , Struck Douglas K. , Young Ry
Published: September 2005

Bacteriophage T4 effects host lysis with a holin, T, and an endolysin, E. T and E accumulate in the membrane and cytoplasm, respectively, throughout the period of late gene expression. At an allele-specific time, T triggers to disrupt the membrane, allowing E to enter the periplasm and attack the peptidoglycan. T triggering can be blocked by secondary infections, leading to the state of lysis inhibition (LIN). LIN requires the T4 antiholin, RI, and is sensitive to the addition of energy poisons. T is unusual among holins in having a large C-terminal periplasmic domain. The
rI
gene encodes a polypeptide of 97 residues, of which 72 are predicted to be a periplasmic domain. Here, we show that the periplasmic domain of RI is necessary and sufficient to block T-mediated lysis. Moreover, when overexpressed, the periplasmic domain of T (T
CTD
) was found to abolish LIN in T4 infections and to convert wild-type (wt) T4 plaques from small and fuzzy edged to the classic “
r
” large, sharp-edged plaque morphology. Although RI could be detected in whole cells, attempts to monitor it during subcellular fractionation were unsuccessful, presumably because RI is a highly unstable protein. However, fusing green fluorescence protein (GFP) to the N terminus of RI created a more stable chimera that could be demonstrated to form complexes with wild-type T
CTD
and also with its LIN-defective T75I variant. These results suggest that the function of the unusual periplasmic domain of T is to transduce environmental information for the real-time control of lysis timing.
Small Untranslated RNA Antitoxin inBacillus subtilis
Authors: Silvaggi Jessica M. , Perkins John B. , Losick Richard
Published: September 2005

Toxin-antitoxin (TA) modules are pairs of genes in which one member encodes a toxin that is neutralized or whose synthesis is prevented by the action of the product of the second gene, an antitoxin, which is either protein or RNA. We now report the identification of a TA module in the chromosome ofBacillus subtilisin which the antitoxin is an antisense RNA. The antitoxin, which is called RatA (for RNA antitoxin A), is a small (222 nucleotides), untranslated RNA that blocks the accumulation of the mRNA for a toxic peptide TxpA (for toxic peptide A; formerly YqdB). ThetxpAandratAgenes are in convergent orientation and overlap by ca. 75 nucleotides, such that the 3′ region ofratAis complementary to the 3′ region oftxpA. Deletion ofratAled to increased levels oftxpAmRNA and lysis of the cells. Overexpression oftxpAalso caused cell lysis and death, a phenotype that was prevented by simultaneous overexpression ofratA. We propose that theratAtranscript is an antisense RNA that anneals to the 3′ end of thetxpAmRNA, thereby triggering its degradation.
The Ability ofProteus mirabilisTo Sense Surfaces and Regulate Virulence Gene Expression Involves FliL, a Flagellar Basal Body Protein
Authors: Belas Robert , Suvanasuthi Rooge
Published: September 2005

Proteus mirabilisis a urinary tract pathogen that differentiates from a short swimmer cell to an elongated, highly flagellated swarmer cell. Swarmer cell differentiation parallels an increased expression of several virulence factors, suggesting that both processes are controlled by the same signal. The molecular nature of this signal is not known but is hypothesized to involve the inhibition of flagellar rotation. In this study, data are presented supporting the idea that conditions inhibiting flagellar rotation induce swarmer cell differentiation and implicating a rotating flagellar filament as critical to the sensing mechanism. Mutations in three genes,fliL,fliF, andfliG, encoding components of the flagellar basal body, result in the inappropriate development of swarmer cells in noninducing liquid media or hyperelongated swarmer cells on agar media. ThefliLmutation was studied in detail. FliL−mutants are nonmotile and fail to synthesize flagellin, while complementation offliLrestores wild-type cell elongation but not motility. Overexpression offliL+in wild-type cells prevents swarmer cell differentiation and motility, a result also observed whenP. mirabilis fliL+was expressed inEscherichia coli. These results suggest that FliL plays a role in swarmer cell differentiation and implicate FliL as critical to transduction of the signal inducing swarmer cell differentiation and virulence gene expression. In concert with this idea, defects infliLup-regulate the expression of two virulence genes,zapAandhpmB. These results support the hypothesis thatP. mirabilisascertains its location in the environment or host by assessing the status of its flagellar motors, which in turn control swarmer cell gene expression.
Block observations of neighbourhood physical disorder are associated with neighbourhood crime, firearm injuries and deaths, and teen births
Authors: Wei Evelyn , Hipwell Alison , Pardini Dustin , Beyers Jennifer M , Loeber Rolf
Published: September 2005

Study objective:To provide reliability information for a brief observational measure of physical disorder and determine its relation with neighbourhood level crime and health variables after controlling for census based measures of concentrated poverty and minority concentration.

Design:Psychometric analysis of block observation data comprising a brief measure of neighbourhood physical disorder, and cross sectional analysis of neighbourhood physical disorder, neighbourhood crime and birth statistics, and neighbourhood level poverty and minority concentration.

Setting:Pittsburgh, Pennsylvania, US (2000 population = 334 563).

Participants:Pittsburgh neighbourhoods (n = 82) and their residents (as reflected in neighbourhood level statistics).

Main results:The physical disorder index showed adequate reliability and validity and was associated significantly with rates of crime, firearm injuries and homicides, and teen births, while controlling for concentrated poverty and minority population.

Conclusions:This brief measure of neighbourhood physical disorder may help increase our understanding of how community level factors reflect health and crime outcomes.
REPRESENTATION OF THE HEISENBERG ALGEBRA h4 BY THE LOWEST LANDAU LEVELS AND THEIR COHERENT STATES
Authors: FAKHRI H. , SHADMAN Z.
Published: September 2005

Using simultaneous shape invariance with respect to two different parameters, we introduce a pair of appropriate operators which realize shape invariance symmetry for the monomials on a half-axis. It leads to the derivation of rotational symmetry and dynamical symmetry group H4 with infinite-fold degeneracy for the lowest Landau levels. This allows us to represent the Heisenberg–Lie algebra h4 not only by the lowest Landau levels, but also by their corresponding standard coherent states.
TECHNIQUES IN ANALYTIC LAMB SHIFT CALCULATIONS
Authors: JENTSCHURA ULRICH D.
Published: September 2005

Quantum electrodynamics has been the first theory to emerge from the ideas of regularization and renormalization, and the coupling of the fermions to the virtual excitations of the electromagnetic field. Today, bound-state quantum electrodynamics provides us with accurate theoretical predictions for the transition energies relevant to simple atomic systems, and steady theoretical progress relies on advances in calculational techniques, as well as numerical algorithms. In this brief review, we discuss one particular aspect connected with the recent progress: the evaluation of relativistic corrections to the one-loop bound-state self-energy in a hydrogenlike ion of low nuclear charge number, for excited non-S states, up to the order of α(Zα)6 in units of the electron mass. A few details of calculations formerly reported in the literature are discussed, and results for 6F, 7F, 6G and 7G states are given.
MIRROR BRANES
Authors: SHTANOV YURI , VIZNYUK ALEXANDER
Published: September 2005

The Randall–Sundrum two-brane model admits the flat-brane Lorentz-invariant vacuum solution only if the branes have exactly opposite tensions. We pay attention to this condition and propose a generalization of this model in which two branes are described by actions of the same form and with the same matter content but with opposite signs. In this way, the relation between their tensions (which are their vacuum energy densities) is naturally accounted for. We study a simple example of such a model in detail. It represents the Randall–Sundrum model supplemented by the Einstein scalar-curvature terms in the actions for the branes. We show that this model is tachyon-free for sufficiently large negative values of the brane cosmological constant, that gravitational forces on the branes are of opposite signs, and that physically most reasonable model of this type is the one where the five-dimensional gravity is localized around the visible brane. The massive gravitational modes in this model have ghost-like character, and we discuss the significance of this fact for the quantum instability of the vacuum on the visible brane.
ON HUNT PROCESSES AND STRICT CAPACITIES ASSOCIATED WITH GENERALIZED DIRICHLET FORMS
Authors: TRUTNAU GERALD
Published: September 2005

Introducing the corresponding strict capacity, we give necessary and sufficient conditions for a generalized Dirichlet form to be associated with a Hunt process. We also show that Borel measurable sets with strict capacity zero can be checked-out by an appropriate subclass of smooth measures. In the last part of this paper we present applications to three classes of examples.
CHARACTERIZATION OF OPERATORS ON A KONDRATIEV SPACE IN THE NON-GAUSSIAN SETTING: BIORTHOGONAL APPROACH
Authors: YABLONSKY EUGENE
Published: September 2005

A linear bounded operator on a test space of white noise functionals can be characterized in terms of growth conditions imposed on the operator's symbol. This paper extends such characterization to operators on the Kondratiev's test space [Formula: see text] of random variables over a general non-Gaussian probability space.

We follow the biorthogonal approach of Yu. Daletsky and his colleagues. In particular, the test space under consideration is generated by the system of multivariate Appell polynomials defined on the underlying infinite dimensional co-nuclear probability space.

We further extend this biorthogonal approach to operators by providing a biorthogonal chaos decomposition for operators and by giving a biorthogonal construction for an operator's symbol.
QUANTUM MARKOVIAN APPROXIMATIONS FOR FERMIONIC RESERVOIRS
Authors: GOUGH JOHN , SOBOLEV ANDREI
Published: September 2005

We establish a quantum functional central limit for the dynamics of a system coupled to a fermionic bath with a general interaction linear in the creation, annihilation and scattering of the bath reservoir. Following a quantum Markovian limit, we realize the open dynamical evolution of the system as an adapted quantum stochastic process driven by fermionic noise.
Current–Voltage Characteristics of γ-Al2O3/epi-Si Resonant Tunneling Diodes with Different Quantum Well Thicknesses
Authors: Mosammat Halima Khatun , Shahjahan Mohammad , Ito Ryoki , Sawada Kazuaki , Ishida Makoto
Published: September 2005

The fabrication of double-barrier resonant tunneling diodes (DBRTDs) using γ-Al2O3/epitaxial-Si heterostructures with different well thicknesses and different barrier thicknesses was studied. Current–voltage characteristics of the DBRTDs were investigated to determine the relationships between the peak-to-valley current ratio and the quantum well thickness, and between the peak current density and the barrier thickness for the maximum peak-to-valley current ratio (PVCR) at room temperature. In this study, we confirmed a maximum peak-to-valley current ratio of 26 at room temperature with a quantum well (epi-Si) thickness of 3 nm and a barrier (γ-Al2O3) thickness of 2 nm. A comparison between the theoretical and experimental peak voltage positions for a negative differential resistance was performed, indicating good agreement. A lower peak current density of few mA/cm2 was obtained.
Nanolaminated Ta2O5–Al2O3 Insulator Effect on Luminescent and Electrical Properties of Thin-Film Electroluminescent Devices
Authors: Kim Yong Shin , Yun Sun Jin
Published: September 2005

Three ZnS:Tb alternating-current thin-film electroluminescent (ACTFEL) devices were fabricated with different insulator structures by utilizing nanolaminated Ta2O5–Al2O3 and/or Al2O3. These devices were grown by sequential atomic-layer-deposition processes for bottom insulator, phosphor, and top insulator layers. The nanolaminated ACTFEL device with two Ta2O5–Al2O3 insulators were found to have low onset voltages, 50 V less than that of the Al2O3 device, for inducing conductive charge transfer and concomitant electroluminescence. The devices with the nanolaminated insulator showed more excessive dynamic space charge generation within the phosphor than the Al2O3 device. These insulator-dependent features and various observed electrical responses have been discussed in terms of the difference in the relative dielectric constants of used insulators (7 for Al2O3 and 15 for Ta2O5–Al2O3), and the creation mechanism of dynamic space charge.
Selective Embedded Growth of 4H–SiC Trenches in 4H–SiC(0001) Substrates Using Carbon Mask
Authors: Chen Yi , Kimoto Tsunenobu , Takeuchi Yuichi , Malhan Rajesh K. , Matsunami Hiroyuki
Published: September 2005

Selective embedded growth of 4H–SiC trenches in SiC(0001) substrates utilizing a carbon mask by chemical vapor deposition has been investigated. The SiC trenches have been successfully embedded, and the carbon mask is successfully removed by thermal oxidation. The growth rate inside the SiC trench region on the masked SiC substrates is three times higher than that on nonmasked planar SiC substrates. Micro-Raman scattering measurements reveal that the embedded region is homoepitaxial 4H–SiC.
A comparison on the Electrical Characteristics of SiO2, SiON and SiN as the Gate Insulators for the Fabrication of AlGaN/GaN Metal–Oxide/Insulator–Semiconductor High-Electron Mobility-Transistors
Authors: Balachander Krishnan , Arulkumaran Subramanium , Egawa Takashi , Sano Yoshiaki , Baskar Krishnan
Published: September 2005

We report on the effect of SiO2, SiN and SiON insertion for the demonstration of AlGaN/GaN metal–oxide/insulator–semiconductor high-electron mobility-transistors (MOSHEMTs/MISHEMTs) on sapphire substrates. The compositions of the three dielectrics were confirmed using X-ray photoelectron spectroscopy (XPS). All the three dielectrics showed enhanced drain saturation current density compared to unpassivated high-electron mobility-transistors (HEMTs). The SiO2 MOSHEMTs though exhibited a very low leakage current, suffered from a relatively high degree of current collapse. The SiN MISHEMTs displayed a low drain current collapse, but, suffered from high degree of leakage current compared with other two dielectrics. SiON MOSHEMTs, taking the advantage of both SiO2 and SiN, resulted both in low drain current collapse as well as moderate leakage current. Thus based on the improved dc characteristics, SiON proves to be a potential dielectric candidate as it simultaneously mitigates the problem of current collapse and achieves moderate leakage current.
Strain-Induced Electrical Resistivity and Magnetic Behavior of Paramagnetic Inconel Alloy 600
Authors: Wang Shing Hoa , Chan Feng Shiu , Yao Yeong Der
Published: September 2005

The magnetization and electrical resistivity of a commercial Inconel alloy 600 (alloy of Ni72Cr16Fe8) were studied as functions of plastic deformation. The magnetization (M) versus magnetic field (H) relationships for Inconel 600 take the form of curves. At a slow strain rate of 10-3/s, the slopes of the M–H curves are in order of the as-received material being the largest, following by strain at about 13%, the strain at ultimate tensile strength (UTS) (about 21%), and the fracture strain at about 26% as the smallest. It is evident that the strain rate does not affect the magnetic behavior of this material. Specimens deformed with a high strain rate of 10-1/s exhibit a higher resistivity than those deformed with a low strain rate of 10-3/s.
Substitution Effect on Magnetization Behaviors in Manganese Perovskites La0.7-xYxPb0.3MnO3 (0.0≤x≤0.2)
Authors: Young San-Lin , Horng Lance , Ho Ya-Wen , Chen Hone-Zern , Wu Jong-Ching
Published: September 2005

The magnetization behaviors of La0.7-x
Y
x
Pb0.3MnO3 (0.0≤x≤0.2) have been examined. The replacement of La ions by Y results in a considerable decrease in the ferromagnetic ordering temperature T
C and irreversible behavior in the zero-field cooling and field cooling curves at a low applied field. The saturation magnetization M
S decreases as Y content increases. The results can be explained by the suppression of ferromagnetism due to structure tuning induced by the substitution of Y into the La site.
Wavelength-Dependent Coupling Characteristics in Two-Dimensional Photonic-Crystal Slab Directional Coupler
Authors: Tanaka Yu , Sugimoto Yoshimasa , Ikeda Naoki , Nakamura Hitoshi , Asakawa Kiyoshi , Inoue Kuon
Published: September 2005

This paper describes the fabrication and characteristics of a two-dimensional photonic-crystal slab directional coupler with a coupling length of ∼31 µm. Coupling properties are discussed using the conventional coupled mode theory and band diagrams calculated by a mix of the plane-wave-expansion method and an effective refractive index. Due to the large group velocity dispersion in the presence of the photonic band gap, the coupling properties are shown to be significantly wavelength dependent. Calculated results were compared with experimental results by observing transmission spectra and intensity modulations attributable to optical interference under various experimental configurations. These indicated that the calculated results are in good agreement with observed results.
Fabrication of Dammann Gratings in Silica Glass Using a Filament of Femtosecond Laser
Authors: Li Yudong , Watanabe Wataru , Tamaki Takayuki , Nishii Junji , Itoh Kazuyoshi
Published: September 2005

The Dammann grating is one kind of useful binary optical elements. We fabricated a single-layer birefringence-free 5×5 Dammann grating in silica glass using the filamentation of 800 nm femtosecond laser pulses. The diffraction efficiency of the Dammann grating reached 56%, which is close to the theoretical value of 77%.
Microwave Dielectric Properties and Microstructure of 0.85MgTiO3–0.15Ca0.6La0.8/3TiO3 Dielectric Ceramics with Added Sintering Aids
Authors: Chen Yuan-Bin , Huang Cheng-Liang , Lon Chen-Weng , Wei Chih-Hung , Hsieh Yu-Ping , Huang Yi-Hong
Published: September 2005

The effects of additive sintering aids on the microstructures and microwave dielectric properties of 0.85MgTiO3–0.15Ca0.6La0.8/3TiO3 ceramics were investigated. CuO was selected as a liquid phase sintering aid to lower the sintering temperature of 0.85MgTiO3–0.15Ca0.6La0.8/3TiO3 ceramics. With added CuO, the densification temperature of 0.85MgTiO3–0.15Ca0.6La0.8/3TiO3 can be effectively reduced from 1450 to 1160–1300°C. Low-level doping of CuO (0.5–5 wt %) significantly improves the density and dielectric properties of 0.85MgTiO3–0.15Ca0.6La0.8/3TiO3 ceramics. The quality factor Q×f was strongly dependent upon the amount of additives. Q×f values of 60000 and 20000 GHz could be obtained at 1160–1300°C with 0.5 and 5 wt % CuO added, respectively. Over all ranges of addition, the relative dielectric constants differed significantly and ranged from 23.2 to 26.1. The temperature coefficient varied from 0 to -3.7 ppm/°C.
A Novel Process for Fabrication of Gated Silicon Field Emitter Array Taking Advantage of Ion Bombardment Retarded Etching
Authors: Tanii Takashi , Fujita Satoru , Numao Yoshiteru , Matsuya Iwao , Sakairi Mitsuaki , Masahara Meishoku , Ohdomari Iwao
Published: September 2005

A novel process for the fabrication of a gated silicon field emitter array is proposed. The process involves complete self-alignment of gate electrodes taking advantage of ion bombardment retarded etching. The ion-irradiated regions serve as masks for subsequent silicon etching resulting in the formation of tabletop structures. The structures are suitable for both the formation of pyramidal emitters and the arrangement of gate electrodes adjacent to each emitter. We integrate this silicon etching into a self-align process for the fabrication of gated emitter array. The emission characteristics of 100 emitters are tested, and the emission at a gate voltage of 30 V is detected. The results indicate that the proposed process is applicable to the fabrication of gated silicon emitters.
The Low-Temperature Synthesis and Optical Properties of Near-White Light Emission Nanophosphors Based on Manganese-Doped Zinc Sulfide
Authors: Lu Hao-Ying , Chu Sheng-Yuan , Tan Soon-Seng
Published: September 2005

Manganese-doped zinc sulfide as a nano scale phosphor has been prepared via a solid-state reaction employing zinc acetate, manganese acetate and thioacetamide (TAA). At a synthesis temperature of 100–300°C, the structure of 2 mol % Mn2+-doped ZnS nanoparticles was cubic, as identified from X-ray diffraction (XRD) patterns. Four temperatures were adopted to synthesize 2 mol % Mn2+-doped ZnS with particle sizes ranging from 3.9 to 7.0 nm. According to the quantum size effect, the increases in ZnS band-gap energy (calculated from photoluminescence excitation spectra and the Brus formula) were examined, and similar tendencies were obtained in the results of the two methods. From the photoluminescence (PL) spectra, two emission bands (blue-light emission and orange-light emission) were observed. The blue-light emission band resulted from the energy level of the ZnS matrix, and the orange-light emission band was assigned to the 4
T
1→6
A
1 transition of a Mn2+ ion in a ZnS matrix. By controlling the synthesis temperature, the ratio of the two light-emission intensities was tuned by increasing the excitation surface of ZnS matrix material. According to Commission Internationale de L'clairage (CIE) coordinates, a near-white-light emission was observed by this simple and rapid method.
Diameter-Controlled Growth of Multi-Walled Carbon Nanotubes by Hot-Filament Chemical Vapor Deposition with Ferritin as a Catalyst on a Silicon Substrate
Authors: Kondo Daiyu , Sato Shintaro , Kawabata Akio , Awano Yuji
Published: September 2005

Diameter-controlled growth of multi-walled carbon nanotubes (MWNTs) has been achieved by hot-filament chemical vapor deposition with ferritin, a nano-bio-molecule, as a catalyst on a silicon substrate. Ferritin molecules are proteins containing iron oxide cores, which have a uniform diameter dependent on the ferritin size. MWNT growth was performed in a low-pressure chamber using acetylene at 540°C. In contrast to former cases, ferritin cores did not coalesce on the substrate without any additives or porous structures, due to the low growth temperature. The geometric mean diameter of the resultant MWNTs is consistent with that of iron oxide cores. It has also been found that a titanium layer on a silicon substrate assists the growth of MWNTs. The results indicate that ferritin is a good candidate catalyst for growing diameter-controlled MWNTs for electrical applications.
Au Alloy Formation with Sn–Pb or Sn–Zn Solder Nanoparticles
Authors: Shintaku Masayuki , Suzuki Hitoshi , Kamitsuji Katsuya , Kaito Chihiro
Published: September 2005

Structures of simultaneously evaporated Sn–Pb and Sn–Zn nanoparticles on amorphous carbon surfaces have been elucidated using a transmission electron microscope. Spontaneous alloy formations by the deposition of Au have been observed at room temperature on a clean particle surface. AuSn2, Au3Zn and AuPb2 ordered alloys have predominantly been produced. It was also shown that the spontaneous formation of oxide film with the thickness of 5.0 nm order upon exposure to air prevents the alloy formation even with heating at 300°C.
Fabrication of Gold Dot and Tubular Gold Arrays Using Anodic Aluminum Oxide Film as Template
Authors: Jung Kyung-Han , Yoon Jong-Won , Koshizaki Naoto , Kwon Young-Soo
Published: September 2005

We attempted to fabricate highly ordered gold dot and tubular gold arrays by thermal evaporation and radio frequency (rf) sputtering deposition using an anodic aluminum oxide (AAO) film as template. Both arrays were precisely reproduced corresponding to the hexagonal structure of the AAO film. In the gold dot arrays, the average diameter of dots is approximately the same as the AAO pore sizes in the range from 65 to 90 nm. Using rf sputtering deposition, tubular gold arrays were formed. The tubular gold arrays were 65 nm in inner diameter, 20 nm in wall thickness and 100 nm in intercenter spacing. Energy dispersive spectrometry (EDS) indicated that the gold dot and tubular gold arrays mainly consisted of a precious metal gold.
Ultrahigh-Density Ferroelectric Data Storage Based on Scanning Nonlinear Dielectric Microscopy
Authors: Cho Yasuo
Published: September 2005

Ferroelectrics have generated considerable interest as promising storage media. In this paper, an investigation of ultrahigh-density ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) is described. For the purpose of obtaining fundamental knowledge on high-density ferroelectric data storage, several experiments on nanodomain formation in a lithium tantalate (LiTaO3) single crystal were conducted. As a result, a very small inverted domain with a radius of 6 nm was successfully formed in stoichiometric LiTaO3 (SLT), and a domain dot array with an areal density of 1.5 Tbit/in.2 was formed on congruent LiTaO3 (CLT). Moreover, it was found that fast nanosecond domain switching could be achieved by reducing the thickness of a CLT plate sample. Additionally, the prototype high-density ferroelectric data storage system was developed. Using this system, writing data transfer rates were evaluated and 256×256 bit data were recorded with the areal densities of 258 and 717 Gbit/in.2
Site-Selective Deposition of Au Nanoparticles on Au Islands on Highly Oriented Pyrolytic Graphite Substrate Using DNA-Based Method
Authors: Maeda Yasushi , Maeda Yukiko Y. , Okada Tomoko , Kodaka Masato , Fujitani Tadahiro , Tsubota Susumu
Published: September 2005

A DNA-based method was applied to the site-selective deposition of Au nanoparticles on Au islands on a highly oriented pyrolytic graphite (HOPG) substrate. Au particles of 10 nm diameter were modified with thiolated single-stranded DNA (SH-ssDNA), and then attached to Au islands modified with complementary SH-ssDNA through DNA hybridization. Atomic force microscopy observations revealed that the deposition of Au particles was dependent on the SH-ssDNA concentration in the treatment of Au/HOPG substrates. It was found that Au particles were selectively deposited on Au islands when the Au/HOPG substrate was treated with 100 nmol/L SH-ssDNA.
Actinic Mask Inspection Using an EUV Microscope –Preparation of a Mirau Interferometer for Phase-Defect Detection–
Authors: Hamamoto Kazuhiro , Tanaka Yuzuru , Kawashima Hirotake , Lee Seung Yoon , Hosokawa Nobuyuki , Sakaya Noriyuki , Hosoya Morio , Shoki Tsutomu , Watanabe Takeo , Kinoshita Hiroo
Published: September 2005

This paper describes a mask defect inspection system using 13.5 nm light for extreme ultraviolet lithography (EUVL). The Schwarzschild optics which is employed as a microscope optics has a numerical aperture (NA) of 0.3 and a magnification of 30. Furthermore, it has a potential of detecting defects as small as 22 nm on a mask. In order to inspect defects with the phase change induced by swelling of the multilayer, a Mirau interferometer is employed. It is developed that the performance of the optical system, the focal position detection mechanism for image detection while scanning, and the driving mechanism of the reference mirror for the Mirau interference. Since the accuracy of the driving mechanism of the reference was found to be 0.1 nm, enough performance of the ring-shaped piezo actuator for interference measurement was confirmed. Moreover, examples of the mask inspection by this system are shown.
A Simulation of Energy-Filtered Backscattered Electron Signals from Subsurface Cu Interconnect Structures
Authors: Yasuda Masaaki , Suzuki Yusuke , Kawata Hiroaki , Hirai Yoshihiko
Published: September 2005

The exit energy dependence of backscattered electron signals from subsurface Cu interconnect structures is studied using a Monte Carlo simulation of electron scattering. The exit energies of the backscattered electrons reflect the depth of the Cu layers accessible in the samples and the energy-filtered backscattered electron signals provide more depth information on the sample structures than the total backscattered electron signals. The effects of the sample geometry on the energy-filtered backscattered electron signals are discussed for several structures.
Laser Shock Removal of Nanoparticles from Si Capping Layer of Extreme Ultraviolet Lithography Masks
Authors: Lee Sang-Ho , Kang Young-Jae , Park Jin-Goo , Busnaina Ahmed A. , Lee Jong-Myung , Kim Tae-Hoon , Zhang Guojing , Eschbach Florence , Ramamoorthy Arun
Published: September 2005

A new dry laser shock wave generated by a Nd:YAG laser was applied to remove nanosized polystyrene latex (PSL) particles on the silicon capping layer of an extreme ultraviolet lithography (EUVL) mask. UV laser was irradiated on the surface before irradiation with laser shock waves to increase the removal efficiency of the organic PSL particles. Owing to the expected damage to the surfaces, the energy of the UV laser was reduced to 8 mJ and the gap distance between the laser shock wave and the surface was increased to 10.5 mm. UV irradiation alone resulted in the removal of 50% of the particles. Exposure to the UV laser three times increased the removal efficiency to 70%. Over 95% particle removal efficiency was found when a laser shock wave was combined with the UV laser. However, the removal efficiency of the particles was below 25% by laser shock wave cleaning alone. Enhanced removal efficiency by UV laser irradiation may be attributed to the photothermal and chemical effects of UV light on the organic PSL particles.
Impact of Long-Period Line-Edge Roughness (LER) on Accuracy in Critical Dimension (CD) Measurement and New Guideline for CD Metrology
Authors: Yamaguchi Atsuko , Fukuda Hiroshi , Kawada Hiroki , Iizumi Takashi
Published: September 2005

The influence of long-period line-edge roughness (LER) on measured critical dimension (CD) is identified, and a guideline is proposed for CD measurement which is free from LER impact. The width of a line pattern measured by critical dimension scanning electron microscope (CD-SEM) is a local CD, which deviates from the averaged CD due to long-period LER. This LER impact on the CD measurement is investigated in two typical measurements of CD-SEM, namely, the evaluation of across-wafer CD variation and the dynamic repeatability of the equipment. It is shown that both results strongly depend upon the height of the inspection area along the pattern edge (L) due to long-period LER. To obtain an accurate CD, this LER impact on variation in measured CD should be reduced sufficiently. It is found that a large L can reduce LER impact, and a 2-µm-high inspection area is recommended for CD measurement. Furthermore, the validity and limitation of the “patchwork method”, in which plural inspection areas are connected to obtain one large area, are examined.
Fabrication of Low Line Edge Roughness Mold by Spin On Glass (SOG) Replica Method
Authors: Kurashima Yuichi , Hiroshima Hiroshi , Komuro Masanori , Yamazaki Naoto , Taniguchi Jun , Miyamoto Iwao
Published: September 2005

This paper reports on the fabrication of a low line edge roughness (LER) mold by the spin on glass (SOG) replica method. The fabrication technique provides a transparent mold with a low LER. In the mold fabrication, the combination of a low LER Si master mold made by anisotropic wet etching and the SOG replica process is effective in reducing fluctuation of the transparent mold pattern. Using this method, we could obtain an LER of SOG replica mold as low as 0.80 nm. When this SOG replica mold was used for photo-nanoimprint, the LER of the patterns on the photocurable polymer, used for the process, was found to be 0.86 nm which is considered quite comparable to the LER of the patterns on the Si master mold. Moreover, using the SOG replica mold, we also nanoimprinted a 60 nm line and space (L/S) pattern with an aspect ratio of 2 and 30 nm L/S patterns.
Nanodot and Nanorod Formation in Electron-Beam-Induced Deposition Using Iron Carbonyl
Authors: Shimojo Masayuki , Zhang Wei , Takeguchi Masaki , Tanaka Miyoko , Mitsuishi Kazutaka , Furuya Kazuo
Published: September 2005

Electron-beam-induced deposition is a promising technique for producing position-controlled nanometer-sized structures without using masks. In this study, electron-beam-induced deposition was carried out using iron carbonyl, and nanometer-sized dots and freestanding rods were fabricated. The nanostructures were characterized by scanning and transmission electron microscopy. The size of the nanodots as a function of beam irradiation time, and the width of the freestanding rods as a function of beam scan speed are reported. Nanocrystal formation under an area scan is also reported.
Synthesis, Monolayer Formation, and Control of Electrical Characteristics of 3-nm-Diameter Gold Nanoparticles
Authors: Arai Tadashi , Saito Shin-ichi , Fukuda Hiroshi , Onai Takahiro
Published: September 2005

A two-dimensional (2D) artificial lattice composed of metal nanoparticles was fabricated and its electrical characteristics were controlled. Each nanoparticle was a 3-nm-diameter gold core covered with thiolate ligands. The fabrication of the 2D artificial lattice was achieved by using the Langmuir-Blodgett method. The conductance of the lattice increases with decreasing length of the thiolate ligands. As well as by the chemical approach, the conductance can also be controlled by a physical approach such as applying an external pressure.
Study on Energy Band of InGaN/GaN Self-Assembled Quantum Dots by Deep-Level Transient Spectroscopy
Authors: Kim Eun Kyu , Kim Jin Soak , Kwon Soon-Yong , Kim Hee Jin , Yoon Euijoon
Published: September 2005

We characterized the energy band of an In-rich InGaN/GaN quantum dot (QD) system with a metal-insulator-semiconductor (MIS) structure by performing optical and electrical measurements. We found several electron traps that have the activation energies of 0.16, 0.40, 0.61, and 0.73 eV with the emission cross sections of 2.16×10-19, 2.23×10-16, 8.61×10-15 and 3.04×10-16 cm2, respectively. The origins of the traps were considered to be an N-vacancy, a QD state, an anti-site point defect and an interface state of the MIS structure. The bound state of QDs was determined to be 0.40 eV from the edge of the GaN barrier and had a capture barrier of 0.16 eV generated by strain between the InGaN and GaN materials.
Control of InAs Quantum Dot Emission Wavelengths in Narrow Regions by Selective Formation of GaInAs Covered Layers Grown with in situ Mask
Authors: Ohkouchi Shunsuke , Nakamura Yusui , Nakamura Hitoshi , Asakawa Kiyoshi
Published: September 2005

We have succeeded in controlling the emission wavelength of a self-assembled InAs quantum dot (QD) structure in a narrow region. The emission wavelength of the QDs was varied locally by a covered GaInAs layer grown with an in situ mask, which can be fitted to the sample holder and removed in an ultra-high-vacuum environment. This mask enables the selective growth of high-quality self-assembled QDs with the desired emission wavelengths ranging from 1.23 µm to 1.32 µm. This technique has potential applications in the integration of microstructures with QDs into optoelectronic functional devices.
Numerical Investigation of Defect Printability in Extreme Ultraviolet (EUV) Reflector: Ru/Mo/Si Multilayer System
Authors: Kang In-Yong , Ahn Jinho , Oh Hye-Keun , Chung Yong-Chae
Published: September 2005

The defect printability of Mo/Si and Ru/Mo/Si multilayer (ML) systems for extreme ultraviolet (EUV) reflectors was quantitatively investigated by monitoring aerial images on a wafer. The aerial image intensity of the Ru/Mo/Si model was calculated and compared with that of the Mo/Si model for various defect widths, heights, and positions. The aerial image characteristic of the defective ML structure turned out to be mainly dependent on defect height, which is related to the phase shift of the reflected field. Peak intensity and peak position shift according to the lateral position were calculated on an ML mask with a 50 nm L/S pattern. Through the investigation of the aerial image characteristics of the two models, it can be concluded that the Ru/Mo/Si model seems to be consistent with the Mo/Si model for all cases within ∼6%.
Nanolithography Based on Photocatalysis of TiO2 Using an Atomic Force Microscope
Authors: Kobayashi Kenkichiro , Tomita Yasumasa , Maeda Yasuhiha
Published: September 2005

Stearic-acid films have been deposited on single-crystalline TiO2(110) substrates by vacuum evaporation. No changes are seen in atomic-force microscope (AFM) topographic images of the stearic-acid films after a scan at a bias voltage of -10 to 10 V in the dark. Similarly, ultraviolet irradiation at bias voltage < 0.0 V brings about no changes in the AFM topographic images. In contrast, a rectangular hole with a size of 200 nm×200 nm is formed in the stearic-acid film after a scan at 10 V under ultraviolet irradiation. No current flows on the stearic-acid film, whereas an appreciable current flows at -2.0 V at the rectangular hole. Photocatalytic decomposition of the stearic-acid films deposited on the TiO2(110) substrates occurs at the area in which a bias voltage of 10 V is applied. The letters “YT” with a line width of 30 nm are drawn in the stearic-acid film by AFM-based photocatalysis.
Mobility and Charge Density Tuning in Double-Doped Enhancement-Mode Pseudomorphic High-Electron-Mobility Transistors Grown by Metalorganic Chemical Vapor Deposition
Authors: Lee Chong-Yi , Shiao Hung-Pin , Kuo Kuan-Chu , Wu Hsin-Yen , Lin Wen-Hsiang
Published: September 2005

We present mobility and charge density tuning for metalorganic chemical vapor deposition (MOCVD)-grown double-doped enhancement-mode (E-mode) pseudomorphic high-electron-mobility transistors (PHEMTs) by varying the supplier layer doping level and spacer layer thickness. From the resolvable Pendellosung oscillation in double-crystal X-ray diffraction measurements and a pronounced two-dimensional electron-gas peak in capacitance–voltage (C–V) analyses, good epitaxial wafers are obtained by MOCVD. The 1-µm-gate-length E-mode PHEMT device exhibits a good pinch-off characteristic with a threshold voltage of 0.025 V and a maximum transconductance of 203 mS/mm. The dependences of the pinch-off characteristic in C–V measurement on sheet carrier concentration and spacer layer thickness for E-mode PHEMT application is also described in detail.
Enhanced Hot-Hole Induced Degradation of Strained p-Channel Metal Oxide Semiconductor Transistors in Complementary Metal Oxide Semiconductor Technology with 2.0 nm Gate Oxide
Authors: See Kwang-Seng , Lau Wai-Shing , Lee Jae Gon , Toh Suey-Li , Liao Hong , Li Kun , Quek Elgin Kiok-Boone , Chan Lap-Hung
Published: September 2005

The effects of process-induced strain silicon (PSS) technology on hot-hole induced degradation of p-channel metal oxide semiconductor (PMOS) transistors using 2.0 nm ultra-thin nitrided gate oxides will be reported. An understanding of the effects of strain on hot-hole induced degradation will be very important for sub-65 nm complementary MOS (CMOS) technology since PSS technology was said to be a preferred approach to strain transistors. It was discovered that as source drain diffusion length (L
ov) decreased, which then gave rise to high compressive strain (HCS) in the channel region of the PMOS transistor, hot-hole induced degradation was enhanced. The improved direct-current current–voltage (IDCIV) method, which allows us to characterize both interface traps (N
it) and oxide charge traps (N
ot) generation, suggested that no additional interface trap (ΔN
it) generation was created when the strain profile of the channel was changed. However, it was observed that positive charge trappings or slow states was enhanced in HCS PMOS transistors which would lead to enhanced hot hole induced degradation after long term stressing.
An Infrared Sensing Material Using a Large-Grain Polysilicon Film
Authors: Kim Tae-Sik , Lee Hee Chul
Published: September 2005

We first report the feasibility of using large-grain polycrystalline silicon films as a sensing material for infrared bolometers. To increase the average grain size of polysilicon films, we used seed selection through ion channeling, which resulted in a large grain size of 1670 Å. The temperature coefficient of resistance (TCR) at 20°C and the grain boundary defect density of the film were as high as -2.46%/K for a resistivity of 30 Ω cm and about 1.752×1012/cm2, respectively. From the measurement of noise characteristics of the film, the value of k, 1/ f noise parameter, was calculated to be 1.35×10-9. As a result, the estimated detectivity was found to approach 5.6×108 cm Hz1/2/W.
Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device
Authors: Chang Chien C. , Chern Ruey-Lin , Chang C. Chung , Chu Chin-Chou , Chi Jim Y. , Su Jung-Chieh , Chan I-Min , Wang Jih-Fu Trevor
Published: September 2005

In this paper, we study the optical properties of phosphor-screened ultraviolet light emitted by a quantum well through a chamber. The chamber contains randomly distributed red, blue and green phosphors, and is top-covered with a layer of omnidirectional photonic bandgap material. A Monte Carlo ray tracing method is developed to model the absorption, reflection and transmission for the excited radiation of the ultraviolet light as well as the visible light by the individual phosphor particles. The efficiency of emitting white light by synthesizing the visible light through the top substrate is investigated with respect to the weight ratio, the size of phosphor particles, the dimension of the chamber and the reflectivity of the side wall and the bottom substrate.