bluuebunny/crossref_metadata_2025 huggingface dataset:
PREDICTING NEW PRODUCT SALES: THE POST-LAUNCH PERFORMANCE OF 215 INNOVATORS
Authors: KLEINKNECHT ALFRED , VAN DER PANNE GERBEN
Published: May 2011

New product sales are hard to predict. Our analysis of sales performance two years after market launch reveals that three groups of factors do not increase the accuracy of predicting new product sales: (1) A firm's general experience and experience with innovation; (2) High technological competences and strong knowledge networks; (3) Customer involvement in new product development. R&D managers should realise that experience with innovation as well as high technological competences, while possibly helpful during the development stage, do not necessarily enhance an accurate prediction of new product sales. Moreover, other than intuitively expected, networking can be ambiguous: It reduces uncertainty about future sales performance by providing information; but it may also enhance knowledge leaking to competitors, thus increasing probabilities of unexpected failure.
A NEW ALGORITHM FOR SOLVING NONLINEAR BOUNDARY VALUE PROBLEMS ARISING IN HEAT TRANSFER
Authors: MOTSA S. S.
Published: May 2011

In this paper, a very efficient and easy-to-use successive linearization approach for solving nonlinear differential equations is proposed. The implementation of the method is demonstrated by solving three nonlinear differential equations of different complexities arising in heat transfer. New closed form explicit analytic solutions of some of the governing nonlinear equations are obtained and compared with the results of the proposed method and with numerical solutions from the MATLAB in-built routine bvp4c.
Origin Investigation of a Nitrogen-Related Recombination Center in GaAsN Grown by Chemical Beam Epitaxy
Authors: Bouzazi Boussairi , Lee Jong-Han , Suzuki Hidetoshi , Kojima Nobuaki , Ohshita Yoshio , Yamaguchi Masafumi
Published: May 2011

The origin of a N-related recombination center (E1), at around 0.33 eV below the conduction band minimum (CBM) of chemical beam epitaxy (CBE) grown GaAsN, is discussed based on effect of H implantation and dependence of E1 density to As flow rate (TDMAAs). After H implantation, E1 disappears completely whereas two new defects are recorded. The first one (HP1) is a hole trap at around 0.11 eV above the valence band minimum, similar to a N-related hole trap in unintentionally doped p-type GaAsN grown by CBE and expected to be N–H–VGa. The second level (EP1) is an electron trap at around 0.41 eV from CBM, identical to EL5 native defect in GaAs and expected to be VGa–Asi or AsGa–VGa. The atomic structure of E1 is discussed from that of HP1 and EP1 and it is expected to be the split interstitial (N–As)As. This expectation is supported by the peaking behavior of E1 density with As source flow rate.
Evaluation and Reliability Improvement Investigation of Electrical Characteristics of Ba0.9Sr0.1TiO3 Dielectric Films Prepared by Electrophoretic Deposition Method
Authors: Abe Naohiko , Hoshino Masahiko , Kitamura Naoto , Ichiryu Akira , Idemoto Yasushi
Published: May 2011

Ba0.9Sr0.1TiO3 (BST) thin films were deposited by the electrophoretic deposition (EPD) method for an embedded capacitor for printed circuit boards (PCBs). When the dielectric properties were evaluated in air, the leakage current densities were large, from 1×10-2 to 1×10-5 A/cm2 applied at 40 V. On the other hand, when the condition was dry Ar, they greatly decreased to be 5×10-8 A/cm2 at an applied voltage of 40 V. From Fourier-transform infrared (FT-IR) evaluation, the change in dielectric properties caused by changing the measuring atmosphere was attributed to the absorption of moisture in the air. These leakage currents were decreased by coating resin onto the EPD films, even when the measurement was carried out in air. When a resin varnish with 2 wt % concentration was coated onto the film with 1.91 µm thickness annealed at 900 °C for 30 min in N2, the dielectric constant remained almost the same as that of without coating, 221, and the leakage current was 4×10-8 A/cm2 or less at 50 V. The resistance of the resin-coated sample was 10.2 MΩ/cm2 after 1000 h under 85 °C and 85% humidity with a 3.5 V bias.
Approximate Analysis of Cylindrical Ferroelectric Capacitor and Derivation of Drain Current Characteristics in Ferroelectric Gate-All-Around Carbon Nanotube Transistor
Authors: Ibata Masakazu , Ishiwara Hiroshi
Published: May 2011

Drain current vs gate voltage and drain current vs drain voltage characteristics have been derived in a ferroelectric gate-all-around carbon nanotube (CNT) transistor. An approximate analysis to derive the polarization characteristics in a cylindrical ferroelectric capacitor is first presented. It has been found that the characteristics can be approximated by those of a parallel-plate capacitor having the same area as the inner electrode of the cylindrical capacitor and the same thickness as the ferroelectric cylinder. Then, the drain current characteristics of the ferroelectric gate-all-around CNT transistor are derived by combining the analysis on the cylindrical capacitor and the ballistic transport theory on CNT transistors. The gate structure is assumed to be such that CNTs with diameters of 1 and 2 nm are surrounded with a 5-nm-thick poly(vinyliden fluoride–trifluoroethylene) [P(VDF–TrFE)] film. It has been found that, in this structure, the CNT transistor can operate as a memory transistor with an appropriate voltage margin.
Observation of Continuous and Quantized Domain Size and Shape Evolution in Monolayers at Air–Water Interface
Authors: Weis Martin , Ou-Yang Wei , Yamamoto Tetsuya , Matsuoka Yohei , Manaka Takaaki , Iwamoto Mitsumasa
Published: May 2011

Langmuir monolayers of pentadecanoic acid (C15) and dipalmitoyl phosphatidylcholine (DPPC) are investigated in liquid expanded–liquid condensed (LE–LC) phase co-existence region in order to study evolution of circular and undulating LC domains. The Brewster angle microscopy is analyzed to evaluate LC domain size and shape for various average molecular areas. For C15 monolayer circular domain shape and continuous increase of domain size are observed. In contrast, for DPPC monolayer undulating domain shapes are observed, where the mode of oscillations m is quantized depending on the average molecular area. Surprisingly, also the average domain size is quantized and depends on m. These observations are discussed in accordance with the phase rule modified for the monolayer phase co-existence region and observed levels of domain sizes are compared with theories of m-fold distortion.
Hybrid Alignment Induced by Asymmetric Photopolymerization of Liquid Crystal-Reactive Mesogen Composition between Two Plastic Substrates
Authors: Kim Kyoung-Sun , Lee Ji-Hoon
Published: May 2011

A hybrid aligned liquid crystal layer was prepared between plastic substrates by the asymmetric photopolymerization of the reactive mesogen. The planar alignment of liquid crystal molecules was induced on the top substrate facing the UV light by the predominant photopolymerization at this substrate, whereas a homeotropic orientation was induced on the bottom substrate. The extinction ratio of the hybrid aligned samples vs the polymer concentration and the thickness of the liquid crystal layer was examined.
Relation between Monomer Structure and Image Sticking Phenomenon of Polymer-Sustained-Alignment Liquid Crystal Displays
Authors: Nakanishi Yohei , Hanaoka Kazutaka , Shibasaki Masakazu , Okamoto Kenji
Published: May 2011

We investigated the image-sticking phenomenon of polymer-sustained-alignment liquid crystal displays (PSA-LCDs) by the evaluation of residual DC and the difference in tilt angle. Experimental results indicate that the difference in tilt angle affects the image sticking of PSA-LCDs more than the residual DC. We also found that the difference in tilt angle is strongly dependent on the chemical structure of the monomer that forms the polymer layer between the alignment layer and the liquid crystal layer by photopolymerization.
N-Polar III–Nitride Green (540 nm) Light Emitting Diode
Authors: Akyol Fatih , Nath Digbijoy N. , Gür Emre , Park Pil Sung , Rajan Siddharth
Published: May 2011

We report the demonstration of a N-polar InGaN based green light emitting diode (LED) grown by N2 plasma-assisted molecular beam epitaxy (PAMBE). High quality multiple quantum well LEDs with In0.29Ga0.71N quantum wells were grown at a temperature of 600 °C by applying a new growth model. LED structures exhibited green emission, and electroluminescence measurements on the test structure showed peak emission wavelengths varying from 564.5 to 540 nm. The full width at half-maximum reduced from 74 to 63 nm as the drive current was increased to 180 A/cm2. This work is the first demonstration of an N-polar LED with emission in the green wavelength range.
High Extraction Efficiency of GaN-Based Vertical-Injection Light-Emitting Diodes Using Distinctive Indium–Tin-Oxide Nanorod by Glancing-Angle Deposition
Authors: Tsai Min-An , Wang Hsun-Wen , Yu Peichen , Kuo Hao-Chung , Lin Shiuan-Huei
Published: May 2011

The enhanced light extraction and reduced forward voltage of a GaN-based vertical injection light emitting diode (VI-LED) with an indium–tin-oxide (ITO) nanorod array were demonstrated. The ITO nanorod array was fabricated by the glancing-angle deposition method. The employment of ITO nanostructures amplified not only the broadband transmission but also the current spreading. The optical output power of GaN-based VI-LEDs with ITO nanorods was enhanced by 50% compared with a conventional VI-LED at an injection current of 350 mA. The extraction efficiency was dramatically raised from 62 to 93% by the surface ITO nanorods. We also optimized the extraction efficiency of the GaN-based VI-LED with an ITO nanorod array by tuning the thickness of the n-GaN top layer via three-dimensional finite difference time domain (3D-FDTD) simulation.
Multi Junction Solar Cells Stacked with Transparent and Conductive Adhesive
Authors: Sameshima Toshiyuki , Takenezawa Jun , Hasumi Masahiko , Koida Takashi , Kaneko Tetsuya , Karasawa Minoru , Kondo Michio
Published: May 2011

We propose a polyimide transparent adhesive layer dispersed with In2O3–SnO2 (ITO) conductive particles (polyimide-ITO) to be used in the mechanical stacking of solar cells. A 20-µm-thick polyimide-ITO layer had a high transmissivity from 78 to 80% for wavelengths ranging from 500 to 1000 nm and a low connecting resistivity of 2.3 Ω cm2 at minimum. The fabrication of stacked cell consisting of a top hydrogenated amorphous silicon (a-Si:H) p–i–n cell and a bottom hetero-junction with an intrinsic thin-layer (HIT)-type silicon cell was demonstrated using an intermediate polyimide-ITO layer. A high open circuit voltage of 1.34 V was experimentally obtained. Simultaneous electric power generation from the top and bottom solar cells was achieved.
Effect of Excitons in AlGaAs/GaAs Superlattice Solar Cells
Authors: Nishinaga Jiro , Kawaharazuka Atsushi , Onomitsu Koji , Ploog Klaus H. , Horikoshi Yoshiji
Published: May 2011

The effect of excitonic absorption on solar cell efficiency has been investigated using solar cells with AlGaAs/GaAs superlattice active regions. Numerical calculations reveal that excitonic absorption considerably enhances the overall absorption of bulk GaAs. Excitonic absorption shows strong and sharp peaks at the absorption edge and in the energy region above the band gap. Absorption enhancement is also achieved in the AlGaAs/GaAs superlattice. The measured quantum efficiency spectra of AlGaAs/GaAs solar cells are found to be quite similar to the calculated absorption spectra considering the excitonic effect. The miniband structures of the superlattice and the electric field of the p–i–n junction enhance the dissociation of excitons and the extraction of separated carriers. These results suggest that the enhanced absorption by excitons can increase the quantum efficiency of solar cells.
Cluster Co-Existence and DC Field Effect on Re-entrant Spin Freezing Behavior in La0.85Ca0.15Mn0.95Fe0.05O Manganates
Authors: Shah Wiqar Hussain , Jaffari Abdullah Al
Published: May 2011

Linear and non-linear dynamic properties of a re-entrant ferromagnetic polycrystalline bulk La0.85Ca0.15Mn0.95Fe0.05O3 sample are studied using AC susceptibility. The Fe doped La0.85Ca0.15Mn0.95Fe0.05O3 undergoes a ferromagnetic transition at T
C = 174 K and to spin glass (SG) at T
g∼100 K, and a decrease in the AC susceptibility as well as zero-field-cooled (ZFC) magnetization measured using very low DC magnetic fields. The dynamic behavior is investigated in the intermediate temperature range (T
g<T<T
C). A prominent non-linear susceptibility is observed in this range, signifying the decomposition of the FM network into clusters by a random magnetic field which is expected to be generated by PM spins in the FM region. The results are supported by a study of the AC frequency and DC field effect on the non-linear susceptibility.
Quantification of Superiority of Broad-Buffer Diodes
Authors: Nemoto Michio , Yoshimura Takashi , Nakazawa Haruo , Yakubo Kousuke
Published: May 2011

We have quantitatively shown the superiority of broad-buffer (BB) diodes over conventional p–i–n diodes, especially with regard to fast and soft reverse recovery, by measuring a new quantity, Γ, signifying the degree of reverse recovery oscillation (RRO). The performance of switching devices has been evaluated in terms of the forward voltage drop V
F and the reverse recovery loss E
RR up to now, but these quantities cannot assess the inhibition of the RRO, which is another important property of switching devices. The quantity Γ, defined as the difference between the voltage rating and the RRO threshold power-supply voltage, represents how well the RRO is inhibited. We evaluated the performance of diodes having a variety of doping profiles in the n-drift region by numerically calculating V
F, E
RR, and Γ and plotting these quantities in a three-dimensional evaluation space. Our device simulation results clearly show that the values of Γ as well as V
F and E
RR for BB diodes are significantly lower than those for conventional diodes, and that BB diodes should be classified as a new category of diodes in view of their superior reverse recovery characteristics.
Theoretical Investigation of Effect of Side Facets on Adsorption–Desorption Behaviors of In and P Atoms at Top Layers in InP Nanowires
Authors: Yamashita Tomoki , Akiyama Toru , Nakamura Kohji , Ito Tomonori
Published: May 2011

We investigate the adsorption and desorption behaviors of In and P atoms on the (111)A top layer of InP nanowires by an ab initio-based approach. Our calculated results reveal that In adatoms occupy the lattice sites of the wurtzite structure as well as the zinc blende structure in the central area of the (111)A top layer. On the other hand, the wurtzite structure is found to be feasible when In adatoms are located near the side facets. The wurtzite structure is preferentially formed for nanowires with small diameters, when most of the top layer consists of side facets. The difference in adsorption behaviors between the surfaces at the central and near the side facet on the top layer of nanowires is one the of factors determining the crystal structure of InP nanowires.
Properties of Si-Doped a-Plane GaN Grown with Different SiH4 Flow Rates
Authors: Song Keun Man , Kim Chang Zoo , Kim Jong Min , Yoon Dae Ho , Hwang Sung Min , Kim Hogyoung
Published: May 2011

Nonpolar Si-doped a-plane GaN layers were grown using metal organic chemical vapor deposition (MOCVD) with different silane (SiH4) flow rates. The on-axis full width at half maximum (FWHM) of X-ray rocking curves (XRCs) along the c- and m-axis directions showed that Si doping barely affected the anisotropy of a-plane GaN. A decrease in the edge threading dislocations (TDs) with increasing Si doping was confirmed by the decreased off-axis FWHM values of the XRCs. With increasing SiH4 flow rate, both the carrier concentration and mobility increased through a reduction in the edge dislocation density. The photoluminescence (PL) spectra revealed that the PL peak positions were first slightly redshifted and then blueshifted with increasing carrier concentration.
High-Throughput Characterization Method for Crystallization Temperature of Integrated Thin Film Amorphous Alloys Using Thermography
Authors: Aono Yuko , Sakurai Junpei , Shimokohbe Akira , Hata Seiichi
Published: May 2011

We introduce the high-throughput characterization of the crystallization temperature T
x of thin film amorphous alloys integrated into a thin film library. This characterization is achieved using thermography. A new thin film library is designed and fabricated using photolithography and a lift-off process. Using a homogeneous composition thin film library, the validity of the proposed method is confirmed. The crystallization of all samples can be detected simultaneously, and the measured T
x distribution is about 8 K. Three compositionally distributed thin film libraries of the Pd–Cu–Si alloy system were then fabricated using combinatorial arc plasma deposition (CAPD), and the T
x values of the samples on the three libraries were measured. In the three libraries, T
x for 285 amorphous samples could be measured, and there was an obvious distribution in T
x depending on the sample composition. At two selected compositions, the measured T
x values agree with differential scanning calorimetry (DSC) results within 8 K. In terms of throughput, the proposed method achieves a measurement time reduction of 66% compared with a conventional method using DSC. Consequently, the proposed method enables the high-throughput combinatorial characterization of the T
x of thin film amorphous alloys.
Effect of Lithium Absorption at Tetrahedral Site and Isomorphic Substitution on Montmorillonite Properties: A Density Functional Theory Study
Authors: Wungu Triati Dewi Kencana , Diño Wilson Agerico , Dipojono Hermawan Kresno , Kasai Hideaki
Published: May 2011

This study deals with the effect of the isomorphic substitution on the sorption of two Li atoms on montmorillonite using density functional theory (DFT). The isomorphic substitution is carried out by modifying the atomic composition of the upper tetrahedral layer of the montmorillonite by replacing one Si atom with one Al atom on the said position. Note that in the conventional structure, Si atom is located at the upper tetrahedral layer of montmorillonite. Results show that one Li atom is likely to be situated in the vacant tetrahedral site and the other one is in the vacant octahedral site, for both of the two montmorillonite systems (isomorphic substitution and conventional structure). The sorption energy was found to be -6.31 eV at the most stable configuration, that is for the isomorphic substitution.
Density Functional Theory Study on the Interaction of O2 Molecule with Cobalt–(6)Pyrrole Clusters
Authors: Dipojono Hermawan K. , Saputro Adhitya G. , Aspera Susan M. , Kasai Hideaki
Published: May 2011

We have investigated the interaction between cobalt–(6)pyrrole [Co–(6)Ppy] clusters and O2 molecule, including the adsorption and dissociation of O2 molecule using the density functional theory (DFT) calculations. We found that O2 molecule is adsorbed on Co–(6)Ppy clusters with side-on configuration and the O–O bond length elongated around 10%. The elongation of the O–O bond when O2 is adsorbed on the clusters will weaken the O–O bond and increase the reactivity of the molecule. The calculated dissociation energies of O2 molecule on Co–(6)Ppy clusters span from 0.89 to 1.23 eV. The order of the dissociation energy is affected by the amount of the charge transferred from Co–(6)Ppy clusters to the O2 molecule in the transition state.
Effect of the Soft X-rays on Highly Hydrogenated Diamond-Like Carbon Films
Authors: Kanda Kazuhiro , Yokota Kumiko , Tagawa Masahito , Tode Mayumi , Teraoka Yuden , Matsui Shinji
Published: May 2011

The effect of soft X-ray irradiation of diamond-like carbon films in vacuum was investigated using synchrotron radiation (SR). Etching and the desorption of hydrogen upon SR exposure in vacuum occurred in highly hydrogenated diamond-like carbon (H-DLC) films; these processes were not observed in the irradiation of a low-hydrogenated DLC film. The extent of decrease in hydrogen content due to SR exposure was found to decrease with increasing the etching ratio of the H-DLC film. This indicates that hydrogen desorption from the H-DLC films competed with the etching process. Namely, the modified surface, in which hydrogen content was decreased by SR exposure, was immediately removed from the H-DLC film that had a high etching rate.
Effect of K0.5Na0.5NbO3on Properties at and off the Morphotropic Phase Boundary in Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3Ceramics
Authors: Anton Eva-Maria , Jo Wook , Trodahl Joe , Damjanovic Dragan , Rödel Jürgen
Published: May 2011

Lead-free (1-y)(Bi1/2Na1/2TiO3–xBi1/2K1/2TiO3)–yK0.5Na0.5NbO3[(1-y)(BNT–xBKT)–yKNN] (0.1≤x≤0.6 and 0≤y≤0.05) ceramics were prepared with compositions both at as well as off the morphotropic phase boundary (MPB) ofx=0.2 andy=0. It was found that KNN addition destabilizes a ferroelectric order in BNT–BKT at zero electric-field, resulting in low remanent polarization, remanent strain and effective small signald33eff[23 pC/N for (x,y)=(0.2,0.05), 60 pC/N for (0.2, 0.02)], while it does not affect the maximum polarisation and strain at high fields and thus enhances large signal piezoelectric coefficient,d33*[200 pm/V for (0.2,0.05), 217 pm/V for (0.2,0.02)]. This effect of KNN was found to be independent from the MPB and thus equally highd33*values were obtained for compositions at and far off the MPB. Thus, adding KNN to BNT–BKT removes the restriction to remain at exactly MPB position and provides more flexibility while offering equal or even improved strain.
Ionic Conductivity in Uniaxial Micro Strain/Stress Fields of Yttria-Stabilized Zirconia
Authors: Sato Kazuhisa , Suzuki Ken , Narumi Ryo , Yashiro Keiji , Hashida Toshiyuki , Mizusaki Junichiro
Published: May 2011

The influence of uniaxial compressive strain/stress on the O2- ion conductivity of an yttria-stabilized zirconia (YSZ) sample was investigated by using electrochemical measurement. The conductivity was investigated by the AC four-probe method and molecular dynamics simulation. The applied compressive strain/stress ranged from 0 to 0.0003 (stress: 1.5–55 MPa) for the specimen in air at 873, 973, and 1073 K. To clarify the reason for the phenomenon of the decline in conductivity, the relaxation time for the conductivity after the application of strain/stresses was measured. The experimental result revealed that as the applied compressive strain/stress increases, the carrier concentration remains steady, whereas the mobility decreases. The conductivity was decreased with increasing compressive strain, and this trend agreed with that of the simulation results. Therefore, the decrease in mobility was considered to be the reason for the decline in conductivity under compressive strain/stress conditions.
High Temperature-Coefficient of Resistance at Room Temperature in W-Doped VO2 Thin Films on Al2O3 Substrate and Their Thickness Dependence
Authors: Takami Hidefumi , Kawatani Kenichi , Kanki Teruo , Tanaka Hidekazu
Published: May 2011

The temperature coefficient of resistance (TCR) in V1-x
W
x
O2 (VWO) with various W-doping levels and thicknesses were investigated on Al2O3(0001) single crystal substrates. The VWO thin films with an appropriate doping level (x=0.015) showed high TCR over 10%/K just at room temperature (300 K), which was larger than that in other reported high TCR materials. Moreover, no significant change of the TCR property was found based on their thickness dependence, meaning effective enhancement of the sensing performance for bolometric application.
Spatial Distributions of Electron, CF, and CF2Radical Densities and Gas Temperature in DC-Superposed Dual-Frequency Capacitively Coupled Plasma Etch Reactor Employing Cyclic-C4F8/N2/Ar Gas
Authors: Yamaguchi Tsuyoshi , Kimura Tetsuya , Koshimizu Chishio , Takeda Keigo , Kondo Hiroki , Ishikawa Kenji , Sekine Makoto , Hori Masaru
Published: May 2011

On a plasma etch reactor for a wafer of 300 mm in diameter, the spatial distributions of the absolute densities of CF and CF2radicals, electron density (ne), and the gas temperature (Tg) of N2were measured employing the dual frequency of negative dc voltage superposed to a very high frequency (VHF) of 60 MHz capacitively coupled plasma (DS-2f-CCP) with the cyclic- (c-)C4F8/Ar/N2gas mixture. The dc bias was superposed on the upper electrode with a frequency of 60 MHz. The distributions of electron and radical densities were uniform within a diameter of about 260 mm, and took a monotonic decay in regions outside a diameter of 260 mm on the reactor for 300 mm wafers in the reactor. It was found that only CF2density at the radial position between 150 and 180 mm, corresponding to the position of the Si focus ring, dropped, while CF density took a uniform distribution over a diameter of 260 mm. Additionally, at this position, the rotational temperature of N2gas increased to be 100 K larger than that at the center position. CF2radical density was markedly affected by the modified surface loss probability of the material owing to coupling with surface temperature.
Gallic Acid as a Complexing Agent for Copper Chemical Mechanical Polishing Slurries at Neutral pH
Authors: Kim Yung Jun , Kang Min Cheol , Kwon Oh Joong , Kim Jae Jeong
Published: May 2011

Gallic acid was investigated as a new complexing agent for copper (Cu) chemical mechanical polishing slurries at neutral pH. Addition of 0.03 M gallic acid and 1.12 M H2O2 at pH 7 resulted in a Cu removal rate of 560.73±17.49 nm/min, and the ratio of the Cu removal rate to the Cu dissolution rate was 14.8. Addition of gallic acid improved the slurry performance compared to glycine addition. X-ray photoelectron spectroscopy analysis and contact angle measurements showed that addition of gallic acid enhanced the Cu polishing behavior by suppressing the formation of surface Cu oxide.
Characterization of Bistable Hybrid-Twisted Nematic Liquid Crystal Mode by Means of Renormalized Transmission Spectroscopic Ellipsometry
Authors: Goda Kazuya , Toko Yasuo , Takahashi Ryouhei , Takahashi Taiju , Kimura Munehiro , Akahane Tadashi
Published: May 2011

We report on how to determine asymmetrical director distribution throughout a liquid crystal layer such as a bistable hybrid-twisted nematic (BHTN) liquid crystal device by means of renormalized transmission spectroscopic ellipsometry. The advantage of the plural oblique incidence spectroscopic ellipsometry (POISE) is that the azimuthal angle as well as the tilt angle with a relatively high zenithal angle can be determined simultaneously without using a special cell with a coupling prizm. It was demonstrated that five device parameters, namely, cell gap, pretilt angles of upper and lower surfaces, twist angle of the director alignment, and azimuthal angle of the entrance liquid crystal director, can be determined uniquely. It is experimentally confirmed that each bistable state has an opposite twist sense and the twist angle difference between two stable states is approximately 180°.
Optimization of Bandwidth and Signal Responses of Optically Pumped Atomic Magnetometers for Biomagnetic Applications
Authors: Kamada Keigo , Taue Shuji , Kobayashi Tetsuo
Published: May 2011

Recently developed ultrasensitive optically pumped atomic magnetometers are promising for biomagnetic measurements such as magnetoencephalograms and magnetocardiograms. The magnetometer's bandwidth and amplitude of signal response are important factors for biomagnetic measurements. These factors depend on various operating parameters such as power density and wavelengths of laser beams. By focusing on the transverse spin relaxation time, we theoretically and experimentally studied the change in the bandwidth and amplitude of the signal response. By considering the effect of the attenuation of a pump beam inside a cell, we showed good agreement between theoretical and experimental results. Furthermore, the magnetometer's integrated performances for the factors were evaluated by changing the power density of the pump beam. Measured data indicated that the bandwidth of signal response depended on the power density of the pump beam and that the bandwidth could be tuned to a desirable frequency range.
Pulse Analyzing System Using Optical Coherence Tomography for Oriental Medical Application
Authors: Jung Unsang , Jeon Mansik , Lee Changho , Cho Namhyun , Jeong Hyosang , Na Changsu , Kim Jeehyun
Published: May 2011

In oriental medicine, the pulse wave of a radial artery is a critical diagnosis factor. An oriental doctor puts a finger on the radial artery to sense the pulse wave of a radial artery. The pulse wave plays an important role because its shape, pressure, and duration determine the pathological status of a patient. Chongumaekbeop, which is a traditional technique for measuring the pulse by using a finger, is sometimes believed to be not reproducible due to the subjective judgment of the measurement location and pulse signal, so we performed a clinical experiment with a developed diagnosis equipment to produce quantitative and reproducible results. In this study, we measured the pulse wave of the radial artery and quantified the speed, intensity, and power of the pulse wave using optical coherence tomography (OCT). We confirmed the applicability of the developed system through an analysis of the pulse wave. We used two OCT systems whose measurement parameters are different because of the measurement limitation and analysis of vector components of pulse movement. We gathered 25 volunteers, compared and analyzed the experiment results with four oriental medicine doctors' diagnosis. The results showed an agreement of 88% in pulse speed, 64% in pulse intensity, and 72% in pulse power when comparing traditional measurements with the system using OCT. We confirmed the dynamical motion detection through the two-dimensional image to ensure the reproducibility of the developed system. Thus, if the OCT system is applied to pulse measurement systems in oriental medicine, it may partially substitute for traditional measurement methods.
Evaluation of a New Advanced Low-k Material
Authors: Smirnov Evgeny A. , Vanstreels Kris , Verdonck Patrick , Ciofi Ivan , Shamiryan Denis , Baklanov Mikhail R. , Phillips Mark
Published: May 2011

New advanced low dielectric constant films (spin-on 2.0) with k = 2.0 were prepared by using a self-assembling technology and deposited by the spin-on method. The open porosity of the films was equal to 40% and they exhibit good mechanical properties (Young's modulus for the pristine sample, thermally cured, is 4.77 GPa and hardness is 0.54 GPa). The principal advantage of these films is the absence of sp2 carbon that is typically formed in porogen based plasma enhanced chemical vapor deposition (PECVD) films and causes high leakage current. The change of the film's properties after UV assisted thermal curing at T = 430 °C with lamps having different wavelengths (narrowband with λ= 172 nm and broadband lamp with λ> 200 nm) was studied. Electrical measurements show a small increase of the k-value, however FTIR spectroscopy shows no bulk and surface hydrophilization after the curing. Observed decreases in thickness and porosity indicate densification of the matrix.
Effects of Postetching Treatment on Molecular-Pore-Stacking/Cu Interconnects for 28 nm Node and Beyond
Authors: Oshida Daisuke , Kume Ippei , Katsuyama Hirokazu , Taiji Toshiji , Maruyama Takuya , Ueki Makoto , Inoue Naoya , Iguchi Manabu , Fujii Kunihiro , Oda Noriaki , Sakurai Michio
Published: May 2011

The effects of postetching treatment (PET) using carbon-containing gas on molecular-pore-stacking (MPS)/Cu interconnects were investigated. By using this technology, a 5% reduction in wiring capacitance was obtained as a result of the hardening of exposed MPS at the trench bottom. Via-chain yield improvement was also confirmed as a result of eliminating of etching residues in via-holes. These results indicate that high production yield and reliability can be obtained by PET for 28-nm-node complementary metal oxide semiconductor (CMOS) devices and beyond.
Influence of the UV Cure on Advanced Plasma Enhanced Chemical Vapour Deposition Low-k Materials
Authors: Verdonck Patrick , Besien Els Van , Vanstreels Kris , Trompoukis Christos , Urbanowicz Adam , Roest David De , Baklanov Mikhail R.
Published: May 2011

In a recent study, low-k thin films with low dielectric constant (≤2.1) and high Young's modulus (>5 GPa) were obtained by introducing a remote plasma step between the traditional plasma enhanced chemical vapour deposition and UV curing. This study shows that the UV curing step with a narrow band lamp with wavelength of 172 nm induced more network Si–O and Si–H bonds and more densification than the curing step with a broadband lamp with wavelengths higher than 200 nm. As a consequence, the dielectric constant of the narrow band cured film was slightly higher, but Young's modulus and hardness were much improved. Electrical characterization showed good breakdown voltages and a more than sufficient time dependent dielectric breakdown reliability. The broadband lamp was then used to form thicker films which retained very well the characteristics of the thin films.
Structure-Modification Model of Porogen-Based Porous SiOC Film with Ultraviolet Curing
Authors: Oka Yoshihiro , Uedono Akira , Goto Kinya , Hirose Yukinori , Matsuura Masazumi , Fujisawa Masahiko , Asai Koyu
Published: May 2011

The effect of ultraviolet (UV) curing on film properties of porogen based porous SiOC (P-SiOC) film was investigated. The P-SiOC films were prepared by plasma-enhanced chemical vapor deposition (PECVD) using alkoxysilane and porogen (hydrocarbon). UV curing time was changed from 0 s to 1000 s. The variation of the k value and elastic modulus on the P-SiOC film with UV curing can be classified into three phases. From the behavior of pore density and free volume rate evaluated by using positron annihilation spectroscopy (PAS), the multiphase model for structural modification of P-SiOC film by UV curing was proposed. In addition, the optimum UV curing time for obtaining a superior P-SiOC film with lower k value and higher mechanical strength was determined.
Analysis of A Novel Slurry Injection System in Chemical Mechanical Planarization
Authors: Meled Anand , Zhuang Yun , Sampurno Yasa Adi , Theng Siannie , Jiao Yubo , Borucki Leonard , Philipossian Ara
Published: May 2011

Slurry mean residence time (MRT), removal rate, and polishing defects were analyzed for a novel slurry injection system used in chemical mechanical planarization. The novel slurry injection system was placed adjacent to the wafer on the pad surface and slurry was injected towards the wafer through multiple holes in the trailing edge of the injector bottom. Results showed the novel slurry injection system provided more efficient slurry delivery to the pad–wafer interface and generated lower slurry MRT, higher removal rate, and lower polishing defects than the standard pad center area slurry application method currently used in the IC manufacturing industry.
Slurry Supplying Method for Large Quartz Glass Substrate Polishing
Authors: Khajornrungruang Panart , Kimura Keiichi , Yui Ryuji , Wada Nagisa , Suzuki Keisuke
Published: May 2011

Chemical mechanical polishing (CMP) has been used in polishing a photomask substrate in flat-panel display (FPD) manufacture. Moreover, the quadrilateral geometry of quartz glass used as the photomask substrate has been enlarged. However, the slurry cannot flow throughout the glass surface evenly owing to the enlarged substrate covering the center of the platen in the polishing process. In this work, we verified the beneficial of spreading slurry into a non-inflow region by the reinforced suction of the slurry supplied to the polishing pad through a hole at center of the platen. A fluorescent agent was used instead of the slurry for flow visualization.
Diamond Conditioner Microwear Effect on Pad Surface Height Distribution in Tungsten Chemical Mechanical Polishing
Authors: Yamada Yohei , Kawakubo Masanori , Kadomura Kazunori
Published: May 2011

In this study, the surface topographies of chemical mechanical polishing (CMP) pad samples for varying levels of diamond microwear of a conditioner have been measured using a confocal microscope and an X-ray computer tomography (CT) scanner. The experimental results showed that the increase in the pad debris on the pad surface reduced the pad height ratio of the asperity called the “top surface area (TSA) ratio”. In addition, the overall removal rate in tungsten CMP was more dependent on the TSA ratio after polishing than on that after conditioning because the pad surface condition became worse with deformed asperities and micropores due to the insufficient conditioning.
Application of Novel Ultrasonic Cleaning Equipment That Uses the Waveguide Mode for the Single-Wafer Cleaning Process
Authors: Suzuki Kazunari , Imazeki Yasuhiro , Han Ki , Okano Shoichi , Soejima Junichiro , Koike Yoshikazu
Published: May 2011

We demonstrate single-wafer cleaning using waveguide-type ultrasonic equipment. The waveguide vibrates as a Lamb wave, and ultrasonic waves of 900 kHz, which is within the megasonic frequency range, radiate from the waveguide side. The waveguide creates a traveling wave field between the waveguide side and wafer surface owing to ultrasonic absorption into the water at the waveguide end. For a traveling wave field, the obtained particle removal efficiency (PRE) was as good as that obtained with conventional batch-type equipment, and cavitation bubble collapse, which induces pattern defects on semiconductor devices, was suppressed. Cavitation bubble collapse was observed using wafers coated with photoresist film, and images of sonoluminescence were captured with a charge coupled device (CCD) camera system.
Formation and Evaluation of Electroless-Plated Barrier Films for High-Aspect-Ratio Through-Si Vias
Authors: Miyake Hiroshi , Inoue Fumihiro , Yokoyama Takumi , Shimizu Tomohiro , Tanaka Shukichi , Terui Toshifumi , Shingubara Shoso
Published: May 2011

The formation of a diffusion barrier layer in a through-Si via (TSV) has been studied with a combination of nanoparticle catalyst and electroless plating (ELP). We used Au-nanoparticles (Au-NPs) or Pd-nanoparticles (Pd-NPs) as catalysts for ELP of Ni- and Co-alloy barrier layers. We studied deposition of Ni–B and Co–B films in high-aspect-ratio (AR) TSV. Then, we succeeded in controlling the deposition profile of Ni–B in a high-AR TSV by the addition of bis(3-sulfopropyl)-disulfide (SPS). SPS turned out to be an inhibitor of electroless plating of Ni–B. On the other hand, the Co–B film was deposited conformally without additive. The electrical resistivity of Cu after annealing Cu/barrier stacked structure suggests that Co–B has better thermal stability than Ni–B.
Characterization of Local Strain around Through-Silicon Via Interconnects by Using X-ray Microdiffraction
Authors: Nakatsuka Osamu , Kitada Hideki , Kim Youngsuk , Mizushima Yoriko , Nakamura Tomoji , Ohba Takayuki , Zaima Shigeaki
Published: May 2011

We have demonstrated the characterization of the local strain structure in thinned Si layers for wafer-on-a-wafer (WOW) applications by using X-ray microdiffraction with a synchrotron radiation source. The microdiffraction reveals the fluctuation of strains in the thin Si layer around through-silicon via (TSV) interconnects with a sub-micrometer scale. We can separately estimated the in-plane and out-of-plane strain structures in the Si layer, and found that the anisotropic strain is induced in the Si layer between the TSV interconnects.
Phase Equilibria, Crystal Chemistry, and Physical Properties of Ag–Ba–Si Clathrates
Authors: Zeiringer Isolde , Bauer Ernst , Grytsiv Andriy , Rogl Peter , Effenberger Herta
Published: May 2011

In the Ag–Ba–Si system the clathrate type I solid solution, Ba8Ag
x
Si46-x
, ranges at 800 °C from Ba8Ag4.3Si41.7 [a = 1.04309(3) nm] to Ba8Ag5.4Si40.6 [a = 1.04613(5) nm]. For all clathrate compositions in this homogeneity region (4.3 ≤x ≤5.4) cubic primitive symmetry with space group P
m3n was confirmed by X-ray powder diffraction assisted by X-ray single crystal analyses of Ba8Ag4.9Si41.1. Site preference from X-ray refinement reveals that silver atoms preferably occupy the 6d site in random mixture with Si. Ba2AgSi3 (Ba4Li2Si6 type, F
d
d
d, a = 0.862, b = 1.493, and c = 1.965 nm), reported by Cardoso et al., was confirmed. Studies of transport properties for Ba8Ag5Si41 evidenced electrons as predominant charge carriers and the closeness of the system to a metal-to-insulator transition.
Characteristics of Chemical Bonds in CuInSe2 and Its Thin-Film Deposition Processes Used to Fabricate Solar Cells
Authors: Wada Takahiro , Maeda Tsuyoshi
Published: May 2011

CuInSe2 (CIS) is one of the I–III–VI2 compound semiconductors with a chalcopyrite-type crystal structure. The characteristics of chemical bonds in CIS differ from those of conventional III–V and II–VI compound semiconductors. The characteristics of chemical bonds in CIS are advantageous for the fabrication of high-quality CIS thin films used in solar cells. The reasons why the “three-stage process” and “selenization process” are used for the fabrication of high-efficiency solar cells are discussed on the basis of recent studies of chemical bonds in CIS.
Room-Temperature Ferromagnetism in (Zn,Mn,Sn)As2 Thin Films Applicable to InP-Based Spintronic Devices
Authors: Uchitomi Naotaka , Oomae Hiroto , Asubar Joel T. , Endo Hironori , Jinbo Yoshio
Published: May 2011

We investigated the growth and magnetic properties of ternary ZnSnAs2 thin films doped with a various degrees of Mn content. It was confirmed that Mn-doped ZnSnAs2 thin films are pseudomorphically grown on nearly lattice-matched InP(001) substrates. Magnetization measurements on Mn-doped ZnSnAs2 thin films revealed a ferromagnetic transition temperature of around 330 K, and clearly showed hysteresis loops even at room temperature. No evidence of magnetic secondary-phase MnAs formation in the host ZnSnAs2 thin films was observed within the limit of our measurement system. We also prepared a trilayer structure consisting of Mn-doped ZnSnAs2 layers and an undoped ZnSnAs2 intermediary layer as a preliminary structure for a tunneling magnetic junction. This structure was confirmed to demonstrate ferromagnetism at room temperature. The present results suggest that diluted ferromagnetic (Zn,Mn,Sn)As2 thin films are one of the most promising building blocks for InP-based spintronic devices.
Peculiarities of Linear Thermal Expansion of CuInS2 Single Crystals
Authors: Nagaoka Akira , Yoshino Kenji , Taniyama Tomoyasu , Miyake Hideto
Published: May 2011

CuInS2 single crystals were grown by a traveling heater method, which is one of the solution growth techniques. The temperature dependence of the X-ray diffraction of CuInS2 was determined between 10 and 300 K. The lattice constant of the a-axis decreased and that of the c-axis increased with increasing temperature. The linear thermal expansion of the c-axis calculated from the lattice constants decreased from 10 to 100 K.
Morphological and Structural Changes in Cu(In,Ga)Se2 Thin Films by Selenization Using Diethylselenide
Authors: Sato Tomoaki , Kawasaki Yoshifumi , Sugiyama Mutsumi , Chichibu Shigefusa F.
Published: May 2011

The morphological and structural changes in Cu(In,Ga)Se2 (CIGS) thin films during selenization using diethylselenide (DESe) are investigated. The surface morphology and extra phase existence of CIGS thin films strongly depend on the heating profile temperature and time of each step during selenization. Conventional high-temperature (515 °C) selenized CIGS thin films formed grains of approximately 2–3 µm, although the Cu–In–Ga metallic precursor was very smooth. On the other hand, the precursor selenized at a low temperature (about 400 °C) exhibited a homogeneous surface morphology because the precursor was formed from Cu–Se and (In,Ga)–Se alloys to diffuse selenide into a Cu–In–Ga metallic precursor. The high-temperature selenized CIGS thin films after low-temperature selenization had a homogeneous surface morphology with appropriate-sized grains. These results indicate that the heating profile “during” selenization was very important in forming Cu–Se and (In,Ga)–Se alloys from a Cu–In–Ga metallic precursor.
Effect of H2S Annealing on Ag-Rich Ag–In–S Thin Films Prepared by Vacuum Evaporation
Authors: Akaki Yoji , Yamashita Kyohei , Yoshitake Tsuyoshi , Nakamura Shigeuki , Tokuda Takahiro , Yoshino Kenji
Published: May 2011

We investigated the effect of H2S annealing on Ag–In–S thin films prepared by vacuum evaporation. In thin films annealed above 350 °C, diffraction peaks except chalcopyrite AgInS2 phase were not observed for a starting material ratio of 1.0 but observed for that of 1.2. Thin films annealed at 400 °C with a starting material ratio of 1.5 contained several phases. We found that the Ag/In ratios of the films could be controlled by changing the starting material ratio. Grains of films with composition ratios of 1.0 and 1.2 were nonuniform, whereas those with a composition ratio of 1.5 were uniform.
Growth of Cu(In,Al)(S,Se)2 Thin Films by Selenization and Sulfurization for a Wide Bandgap Absorber
Authors: Fujiwara Chika , Sato Tomoaki , Kawasaki Yoshifumi , Sugiyama Mutsumi , Chichibu Shigefusa F.
Published: May 2011

The sequentially chalcogenization growth of Cu(In1-x
Al
x
)(S
y
Se1-y
)2 (CIASSe) films while controlling the S/(S+Se) ratio was demonstrated using Cu–In–Al precursor [Al/(Al+In)≤0.05]. These processes of sulfurization following selenization and selenization following sulfurization might be diffusion- and reaction-limited, respectively. Therefore, selenization following the sulfurization of Cu(In,Al)S2 may be suitable for controlling the S/(S+Se) ratio by process temperature and time. These results represent the first step toward realizing a solar cell using a CIASSe film grown by sulfurization and selenization using conventional and large-scale equipment.
Annealing Temperature Dependence of Properties of Cu2ZnSnS4 Thin Films Prepared by Sol–Gel Sulfurization Method
Authors: Maeda Kazuya , Tanaka Kunihiko , Nakano Yuya , Uchiki Hisao
Published: May 2011

Cu2ZnSnS4 (CZTS) thin films were fabricated by a sol–gel sulfurization method with a rapid thermal process. The films preheated at 250 °C for 1 h and sulfurized from 350 to 600 °C for 1 h were investigated. The chemical composition of sulfur was 40% for the preheated film and 50% for the films sulfurized at temperatures higher than 400 °C. The grain size of the films markedly increased with increasing sulfurization temperature from 400 to 450 °C and that of the films sulfurized at temperatures higher than 450 °C was ∼2 µm. The preheated film and the films sulfurized at temperatures lower than 400 °C were composed of Cu
x
S and CZTS. The Cu
x
S phase was eliminated from the CZTS films by sulfurization at temperatures higher than 500 °C.
H2S Concentration Dependence of Properties of Cu2ZnSnS4 Thin Film Prepared under Nonvacuum Condition
Authors: Maeda Kazuya , Tanaka Kunihiko , Nakano Yuya , Fukui Yuki , Uchiki Hisao
Published: May 2011

Cu2ZnSnS4 (CZTS) thin films were prepared by a sol–gel sulfurization method. Sulfurization was carried out in H2S of various concentrations and the properties of the films were investigated. The CZTS thin films sulfurized at 500 °C for 1 h in 0.5 and 3% H2S atmospheres had large grains compared with the film sulfurized in 1% H2S atmosphere. From the X-ray diffraction analysis, the CZTS thin film sulfurized for 1 h in 0.5% H2S atmosphere included a small amount of Cu
x
S as a secondary phase. The films sulfurized for 1 h in 1 and 3% H2S atmospheres were composed of a CZTS phase without Cu
x
S. Owing to the long sulfurization process, the Cu
x
S phase was eliminated and the optical properties of the films were improved. The size of the grains sulfurized in 1% H2S increased with increasing sulfurization time from 2 to 3 h.