bluuebunny/crossref_metadata_2025 huggingface dataset:
EMD APPROACH TO MULTICHANNEL EEG DATA — THE AMPLITUDE AND PHASE COMPONENTS CLUSTERING ANALYSIS
Authors: RUTKOWSKI TOMASZ M. , MANDIC DANILO P. , CICHOCKI ANDRZEJ , PRZYBYSZEWSKI ANDRZEJ W.
Published: February 2010

Human brains exhibit a possibility to control directly the intelligent computing applications in form of brain computer/machine interfacing (BCI/BMI) technologies. Neurophysiological signals and especially electroencephalogram (EEG) are the forms of brain electrical activity which can be easily captured and utilized for BCI/BMI applications. Those signals are unfortunately usually very highly contaminated by external noise caused by the presence of different devices in the environment creating electromagnetic interference. In this paper, we first decompose each of the recorded channels, in multichannel EEG recording environment, into intrinsic mode functions (IMF) which are a result of empirical mode decomposition (EMD) extended to multichannel analysis. We present novel and interesting results on human mental and cognitive states estimation based on analysis of the above-mentioned stimuli-related IMF components. The IMF components are further clustered for their spectral similarity in order to identify only those carrying responses to present stimuli to the subjects. The resulting targets only reconstruction allows us to identify when and to which stimuli intelligent application user is tuning at a time.
3D NOSE FEATURE IDENTIFICATION AND LOCALIZATION THROUGH SELF-ORGANIZING MAP AND GRAPH MATCHING
Authors: BEVILACQUA VITOANTONIO , MASTRONARDI GIUSEPPE , SANTARCANGELO VITO , SCARAMUZZI ROCCO
Published: February 2010

In this paper, two different methodologies respectively based on an unsupervised self-organizing (SOM) neural network and on a graph matching are shown and discussed to validate the performance of a new 3D facial feature identification and localization algorithm. Experiments are performed on a dataset of 23 3D faces acquired by a 3D laser camera at eBIS lab with pose and expression variations. In particular results referred to five nose landmarks are encouraging and reveal the validity of this approach that although low computational complexity and the small number of landmarks guarantees an average face recognition performance greater than 80%.
DESIGN AND MODELING IN THE SOFTWARE PERFORMANCE ENGINEERING DEVELOPMENT PROCESS
Authors: DISTEFANO SALVATORE , PULIAFITO ANTONIO , SCARPA MARCO
Published: February 2010

Performance related problems are becoming more and more strategic in the software development, especially recently with the advent of Web Services and related business-oriented composition techniques (software as a service, Web 2.0, orchestration, choreography, etc.). In particular, an early integration of performance specifications in the SDP has been recognized during the last few years as an effective approach to improve the overall quality of a software. The goal of our work is the definition of a software development process that integrates performance evaluation and prediction. The software performance engineering development process (SPEDP) we specify is focused on performance, which plays a key role driving the software development process, thus implementing a performance/QoS-driven (software) development process. More specifically, in this paper our aim is to formally define the SPEDP design process, posing particular interest on the basis, on the first step of SPEDP, the software/system architecture design, modeling and/or representation. We define both the diagrams to use and show how to model the structure of the software architecture, its behavior and performance requirements. This is the first mandatory step for the automation of the SPEDP into a specific tool, which we have partially implemented as a performance plug-in for ArgoUML, ArgoPerformance.
COMPATIBILITY AS A HEURISTIC FOR CONSTRUCTION OF RULES BY ARTIFICIAL ANTS
Authors: SHAHZAD WASEEM , BAIG ABDUL RAUF
Published: February 2010

Ant Miner algorithms are used for the classification task of data mining. This paper proposes a new version of Ant Miner algorithm called CAnt Miner that considers compatibility between the attributes, when constructing a rule. In addition to a new heuristic function based on compatibility among attributes, we also introduce a strategy to dynamically stop adding terms in the rule antecedent part instead of using a user specified threshold that specifies when to stop adding terms. We compare the performance of proposed approach with other Ant Miner versions and C4.5 in nine public domain data set. The experiment results show that the proposed approach achieves higher accuracy rate then other approaches.
LASER GAS NITRIDING OF TITANIUM AND TITANIUM ALLOYS
Authors: DAI J. J. , HOU S. Q.
Published: February 2010

Titanium and titanium alloys are widely used in many fields due to some of their characteristics such as light density, high strength, and excellent corrosion resistance. However, poor mechanical performances limit their practical applications. Laser gas nitriding is a promising method used to improve the surface properties of components. Recent developments on laser gas nitriding of titanium and titanium alloys are reviewed. The processing parameters have important effects on the resulting characteristics of titanium and titanium alloys. The resulting microstructure and properties of laser gas nitrided specimens are presented. The problems to be solved and the prospects in the field of laser gas nitriding of titanium and titanium alloys are discussed.
EFFECT OFNd:YAGLASER MELTING ON SURFACE ENERGY OF AZ91DMgALLOY
Authors: GUAN Y. C. , ZHOU W. , ZHENG H. Y.
Published: February 2010

Laser surface melting is known to alter surface energy and wettability of a few engineering materials, but its effect on magnesium alloys has never been reported. Effort was made to study how Nd : YAG laser irradiation influenced surface energy of an AZ91D magnesium alloy. Contact angle measurement was carried out using three types of liquids to make it possible to calculate the surface energy quantitatively based upon the acid–base theory. The laser irradiation was found to enhance surface wettability significantly and lead to a drastic increase in surface energy from 25.82 to 40.78 mJ/m2. The change in surface property was attributed to the laser-induced refinement of α- Mg and β- Mg17Al12phases and enrichment of Al in the microstructure.
STUDIES ON THE INHIBITIVE EFFECT OF 3-HYDROXYFLAVONE ON THE ACID CORROSION OF MILD STEEL
Authors: LAVANYA MUTHU NADAR , KESAVAN DEVARAYAN , PRABHAVATHI NAGARAJAN , SULOCHANA NAGARAJAN
Published: February 2010

The corrosion inhibition effect of 3-hydroxyflavone was studied on mild steel in 1 M hydrochloric acid ( HCl ). The anticorrosive effect was evaluated by weight loss and electrochemical methods which include Tafel polarization and AC impedance studies at 300 K. In weight loss method, the inhibition efficiency increased with increase in inhibitor concentration, and decreased with increase in temperature and immersion time, and acid concentration. The inhibitor showed maximum efficiency of 91% at 4 × 10-4 M concentration in 1 M hydrochloric acid. The Tafel polarization study showed that the inhibitor behaves likely as cathodic type. The corrosion inhibition effect measured by weight loss method and electrochemical studies was in good agreement with each other. The surface analysis was done by using scanning electron microscope (SEM). Several adsorption isotherms are assessed to study the adsorption behavior of the inhibitor on the mild steel surface. The negative value of ΔG ads indicates the spontaneous adsorption of the inhibitor on mild steel surface.
WAVE OPTICAL TREATMENT OF SURFACE STEP CONTRAST IN LOW-ENERGY ELECTRON MICROSCOPY
Authors: KENNEDY S. M. , SCHOFIELD N. E. , PAGANIN D. M. , JESSON D. E.
Published: February 2010

A wave optical treatment of surface step contrast in a low-energy electron microscopy (LEEM) is presented. The aberrations of an idealised LEEM imaging system are directly incorporated into a transfer function (TF) and image simulations of surface steps are evaluated in one and two dimensions. Under the special circumstances of a weak phase object, the simplified form of the contrast transfer function (CTF) is used to discuss LEEM image contrast and optimum defocus conditions.
PROPERTIES OF (Bi0.92Ce0.08)2Ti2O7THIN FILMS PREPARED ONSi(100) BY CHEMICAL SOLUTION DECOMPOSITION
Authors: XU GUANGHUI , JING XIANGYANG , ZHANG YIN , HUANG BAIBIAO
Published: February 2010

( Bi0.92Ce0.08)2Ti2O7thin films have been successfully prepared on P-type Si (100) substrates by a chemical solution decomposition method. The structural properties of the films were studied by X-ray diffraction. The phase stability of Bi2Ti2O7was improved after Ce ions were doped. The dielectric constants of ( Bi0.92Ce0.08)2Ti2O7thin films annealed at 650° and 700°C were higher than that of Bi2Ti2O7without Ce modification. The thin films annealed at 650°C showed the highest permittivity. The memory windows in the C – V loops were studied, indicating that the thin films were not ferroelectric thin films. All of these results showed that Ce -doped Bi2Ti2O7thin films had potential for DRAM and MOS applications.
INFLUENCE OF PLASMA PRETREATMENT IN THE FORMATION OF DIAMOND-LIKE CARBON THIN FILMS
Authors: MAHESWARAN R. , RAMASWAMY SHIVARAMAN , MAHAPATRA OJAS , RAO B. PURNACHANDRA , GOPALAKRISHNAN C. , THIRUVADIGAL D. JOHN
Published: February 2010

Plasma-enhanced chemical vapor deposition has been used to synthesize diamond-like carbon (DLC) thin films. High purity argon and methane gases were used as precursors for the fabrication of the DLC films. The influence of plasma pretreatment on the growth of the DLC films has been studied by subjecting one of the substrates to plasma pretreatment prior to deposition of the DLC films, while maintaining the other substrate as the control. The structural properties of the DLC films have been characterized using atomic force microscopy and Raman spectroscopy. The film grown on the pretreated substrate shows a more uniform coating as compared to the film grown on non-pretreated silicon substrate. The results are discussed based on diffusivity of carbon on silicon and the effect of the plasma pretreatment.
EFFECT OF PASSING ELECTRIC CURRENT ON THE ELECTRICAL AND OPTICAL PROPERTIES OF ITO FILMS IN AIR
Authors: PEI YU , LIN LIMEI , ZHENG WEIFENG , QU YAN , HUANG ZHIGAO , LAI FACHUN
Published: February 2010

The effect of passing electric current on the electrical and optical properties of indium tin oxide (ITO) films in air has been studied. Resistivities of the ITO films deposited by direct current magnetron sputtering on glass substrates were about 10.5 × 10-4Ω cm (group A) and 4.3 × 10-4Ω cm (group B). A constant electric current i between 30 and 150 mA was applied to the films in air for 3 h. The results show that there is a critical current (i cri ) for each group sample. i cri of group A is 60 mA and i cri of group B is 90 mA. When i > i cri , the electrical performance declines and optical transmittance increases for the electric annealed sample. However, both the electrical and optical performances may be improved for the annealed film when i ≤ i cri . It is found that the variations in electrical and optical properties of the films strongly depend on the electric power applied to ITO films.
A NEW KINETIC MONTE CARLO METHOD FOR THE THIN FILM GROWTH OF PEROVSKITES
Authors: PETROV P. , MILLER W.
Published: February 2010

We have developed a novel kinetic Monte Carlo method, which simulates the epitaxial growth of oxide films with perovskite structure. First results are presented for two cases of adsorption dynamics for one of the metals — adsorption of single Ti atoms and adsorption of larger particles TiO2 and TiO . For both types of adsorption a two-by-two layer growth was observed. The simulations have been performed for different ratios between the flux of metals and the flux of oxygen.
PREFERENTIAL ORIENTATION GROWTH OF AlN THIN FILMS ON Si(111) SUBSTRATES BY PLASMA-ASSISTED MOLECULAR BEAM EPITAXY
Authors: CHUAH L. S. , HASSAN Z. , ABU HASSAN H.
Published: February 2010

This article reports the use of plasma-assisted molecular beam epitaxy (MBE) to grow AlN on Si (111) substrate at 850°C under UHV conditions for 15, 30, and 45 min. The films were characterized by high-resolution X-ray diffraction (HR-XRD) and micro-Raman spectroscopy. XRD measurement revealed that the AlN was epitaxially grown on Si (111). Micro-Raman result showed that all the allowed Raman modes of AlN and Si were clearly visible. Fourier transform infrared (FTIR) spectroscopy has been used to investigate the A1 (LO) and E1 (TO) modes with frequencies (890–899) cm-1 and (668–688) cm-1, respectively. The results are in good agreement with reported phonon frequencies of AlN grown on Si (111).
Electrical Characterization and Transmission Electron Microscopy Assessment of Isolation of AlGaN/GaN High Electron Mobility Transistors with Oxygen Ion Implantation
Authors: Shiu Jin-Yu , Lu Chung-Yu , Su Ting-Yi , Huang Rong-Tan , Zirath Herbert , Rorsman Niklas , Chang Edward Yi
Published: February 2010

A multienergy oxygen ion implantation process was demonstrated to be compatible with the processing of high-power microwave AlGaN/GaN high electron mobility transistors (HEMTs). A high sheet resistivity and thermally stable isolation were demonstrated. The microstructures of implanted and postannealed specimens were investigated by transmission electron microscopy (TEM). The dependences of the sheet resistivity and different postannealing temperatures were correlated with the defect clusters and microstructure of lattice stacking faults. After 300 °C annealing, the sheet resistivity was higher than 1012 Ω/square, which was attributed to the severe defect interaction eliminating the trapping centers and reducing the leakage current. A maximum output power density of 5.3 W/mm at V
gs=-4 V and V
ds=50 V at 3 GHz was demonstrated on lag-free HEMTs without field plates on sapphire substrate.
Effect of Al0.06Ga0.94N/GaN Strained-Layer Superlattices Cladding Underlayer to InGaN-Based Multi-Quantum Well Grown on Si(111) Substrate with AlN/GaN Intermediate Layer
Authors: Shuhaimi Bin Abu Bakar Ahmad , Watanabe Arata , Egawa Takashi
Published: February 2010

We report effect of the insertion of Al0.06Ga0.94N/GaN strained-layer superlattices (SLSs) cladding underlayer to InGaN-based multi-quantum well (MQW) structure grown on Si(111) substrate with AlN/GaN intermediate layer. The Al0.06Ga0.94N/GaN SLS underlayer improves emission wavelength uniformity and shows a narrower emission full-width at half-maximum (FWHM) than that of conventional GaN underlayer. A Gaussian fitting was performed to photoluminescence (PL) spectra to obtain emission wavelength behavior and integrated intensity of the peak energy. A higher MQW internal quantum efficiency (ηiqe) of 29.4% is obtained in sample with Al0.06Ga0.94N/GaN SLS underlayer than that of 20.6% in GaN underlayer. Transmission electron microscopy (TEM) analysis indicates that the Al0.06Ga0.94N/GaN SLS layer abruptly bends threading dislocation lines thus reduces threading dislocation density to the MQW. Reciprocal space mapping (RSM) suggests that compressive strain in the GaN portion of Al0.06Ga0.94N/GaN SLS forces the abrupt inclination of the threading dislocations.
Strain Effects on Exciton Transition in CdTe Films on GaAs(100) Substrates
Authors: Onodera Chikara , Yoshida Masaaki , Taguchi Tsunemasa
Published: February 2010

We performed photoluminescence (PL) and reflectance characterization of CdTe films on GaAs substrates. Separate emission peaks for heavy- and light-hole free excitons due to induced compressive strain were observed. The strain in a CdTe film is estimated to be ε=-5.28×10-4. By analyzing the PL and reflectance spectra, both heavy- and light-hole free exciton binding energies are estimated to be 9.9 meV. By analyzing the energy separation between the heavy- and light-hole free exciton reflectance dips, the magnitude of the residual compressive strain is determined to be homogeneously distributed within a CdTe film. From the CdTe film thickness dependence of heavy- and light-hole free exciton linewidths, the CdTe film quality is observed to become poor with decreasing CdTe film thickness.
Direct Piezoelectric Properties of Mn-Doped ZnO Epitaxial Films
Authors: Yoshimura Takeshi , Sakiyama Haruka , Oshio Takeshi , Ashida Atsushi , Fujimura Norifumi
Published: February 2010

The direct piezoelectric properties of Mn-doped ZnO epitaxial films prepared by pulse laser deposition was investigated. The resistivity of the ZnO films was markedly decreased by Mn doping. The effective transverse piezoelectric coefficient (e
31,f
) of the ZnO films was measured by substrate bending and collecting developed charges. The dependence of induced charge density on applied strain indicates that the obtained piezoelectric response originates from the spontaneous polarization of the Mn-doped ZnO films. The e
31,f
values of 3 and 5 at. % Mn-doped ZnO films were determined to be -1.09 and -1.10 C/m2, respectively, which are comparable to the theoretical value.
Analysis on Loss Anisotropy of Piezoelectrics with ∞ mm Crystal Symmetry
Authors: Zhuang Yuan , Ural Seyit O. , Tuncdemir Safakcan , Amin Ahmed , Uchino Kenji
Published: February 2010

The key factor for the miniaturization of piezoelectric devices is power density, which is limited by the heat generation or loss mechanisms. There are three loss components for piezoelectric vibrators, i.e., dielectric, elastic and piezoelectric losses. The mechanical quality factor, determined by these three factors, is the figure of merit in the sense of loss or heat generation. In this paper, quality factors of resonance and antiresonance for both k
31 and k
33 vibration modes are derived, and the method to determine loss factors in various directions is provided. For simplicity, we focus on materials with ∞ mm (equivalent to 6 mm) crystal symmetry for deriving the loss factors of polycrystalline ceramics, and ten different loss factors can be obtained from the measurements. Finite element simulations are made to prove the theory, and the analysis also demonstrates the significance of the piezoelectric loss factor which has usually been neglected by previous piezoelectric device designers.
Reduction of Hysteresis in Organic Field-Effect Transistor by Ferroelectric Gate Dielectric
Authors: Chen Xiangyu , Ou-Yang Wei , Weis Martin , Taguchi Dai , Manaka Takaaki , Iwamoto Mitsumasa
Published: February 2010

We studied the reduction of hysteresis in pentacene organic field-effect transistors (OFETs) with a ferroelectric poly(vinylidene fluoride and trifluoroethylene) [P(VDF–TrFE)] dipole layer used as a coating of silicon dioxide gate insulator. Although the OFETs without the dipole layer exhibited a hysteresis caused by carrier trapping, such hysteresis was not observed for the OFETs with the P(VDF–TrFE) layers. Experiments showed that the induced hysteresis could be regulated by the number of P(VDF–TrFE) dipole layers, which were deposited by the Langmuir–Blodgett (LB) technique or the spin-coating method. Finally, we showed that analysis based on an electrostatic model well accounted for the experimental results, i.e., the reduction of hysteresis by means of the ferroelectric layer.
Efficiency Improvement of Silicon Solar Cells by Nitric Acid Oxidization
Authors: Hu Yeng-Cheng , Chiu Ming-Hui , Wang Likarn , Tsai Jing-Long
Published: February 2010

In this study, we investigate the effect of nitric acid oxidation on p-type silicon solar cells. The oxide layer on the surface of a p-type silicon substrate was grown under various growth times and temperatures while under nitric acid treatment. After 30 min of growth at 23 °C, an efficiency improvement of absolute 2% was obtained using our laboratory fabrication process.
High Resolution Imaging of Electrical Properties of a 2-Inch-Diameter Gallium Nitride Wafer Using Frequency-Agile Terahertz Waves
Authors: Hamano Akihide , Ohno Seigo , Minamide Hiroaki , Ito Hiromasa , Usuki Yoshiyuki
Published: February 2010

The reflective spectra of n-type gallium nitride (GaN) samples with various carrier concentrations have been measured in the terahertz region. We observed the different reflective spectra by changing the carrier concentration. The Drude Lorentz model explained well the measured spectra influenced by free carrier effects. In order to obtain electrical properties of the carrier concentration, mobility, and electrical resistivity, we used two terahertz waves generated by a frequency-agile source. Image mapping of these electrical properties on a 2-in.-diameter GaN wafer was demonstrated with a high resolution of 1×1 mm2.
Reflectance Difference Spectroscopy in Vacuum–Ultraviolet Range: Developing Measurement System and Applying to Characterization of SiO2/Si Interfaces
Authors: Ogata Shoichi , Ohno Shinya , Tanaka Masatoshi , Horikawa Tsuyoshi , Yasuda Tetsuji
Published: February 2010

Reflectance difference spectroscopy (RDS) in the vacuum–ultraviolet (VUV) range has been developed for the first time. The spectral range of RDS has been extended up to 8.4 eV by using a D2 lamp, MgF2-based optical elements, and an N2-purged measurement environment. This new technique has been applied to investigate the oxidation-induced optical anisotropies of the Si surfaces with (110), (331), (120), and (113) orientations. The thermal oxidation of the Si(113) surface caused large changes in the RD spectrum, which we interpret as being due to anisotropic morphology at the SiO2/Si interface. Distinct RD changes upon oxidation were also observed above 7 eV for the (110), (331), and (113) surfaces. We ascribe this feature to the optical transitions involving the electronic states of the interface Si–O bonds. These results demonstrate that VUV-RDS is a unique tool for characterizing dielectrics/semiconductor interfaces.
Computational Depth Conversion of Reconstructed Three-Dimensional Object Images in Curving-Effective Integral Imaging System
Authors: Piao Yongri , Shin Dong-Hak , Kim Eun-Soo
Published: February 2010

In this paper, we propose a novel method for the computational depth conversion of reconstructed three-dimensional (3D) object images by a direct pixel mapping (DPM) method in curving-effective integral imaging (CEII) system. In this proposed method, the elemental image array (EIA) of the 3D object is picked up in the CEII system, and then, this EIA is computationally transformed into a depth-converted EIA by the DPM method. Thus, in contrast to a conventional method, with this proposed method, a real and orthoscopic 3D object image with a wide viewing angle can be provided to observers without any data loss in the depth conversion process. Good experimental results finally confirmed the feasibility of the proposed method.
Thermal Characteristics of an Ytterbium-Doped Fiber Amplifier Operating at 1060 and 1080 nm
Authors: Vazquez-Zuniga Luis Alonso , Chung Seunghwan , Jeong Yoonchan
Published: February 2010

We experimentally analyze the temperature dependence of an ytterbium-doped fiber amplifier (YDFA) operating at 1060 and 1080 nm, investigating its spectroscopic characteristics and gain properties in the temperature range of 10 to 100 °C. Our measurement indicates that the change in the operating temperature can give rise to a significant effect on the YDFA performance, which also significantly depends on the operating wavelength. At the output power level of approximately 1.5 W, the temperature change from 10 to 100 °C resulted in a signal power drop of approximately 16% at 1060 nm and 5% at 1080 nm, respectively. While this is due mainly to the temperature-dependent spectroscopic characteristics of the gain fiber, it also depends on the input signal and pump power levels. We numerically model this behavior, based on the given experimental conditions and measured fiber parameters. Our numerical results are in good agreement with the experimental results and further suggest that higher seed power to the amplifier should help in minimizing the temperature dependence of the YDFA.
Crystal Growth and Luminescence Properties of Tm:BaF2 Single Crystals
Authors: Abe Naoto , Yokota Yuui , Yanagida Takayuki , Pejchal Jan , Nara Fumiko , Kawaguchi Noriaki , Fukuda Kentaro , Nikl Martin , Yoshikawa Akira
Published: February 2010

BaF2 is an intensively studied scintillator for the detection of gamma radiation due to its relatively high stopping power, radiation hardness and extremely fast response. BaF2 possesses the fast cross-luminescence component at 195 and 220 nm with a lifetime of several hundred picoseconds. However, this component coexists with slow one at 310 nm related to the self-trapped exciton (STE). In our present study, we focused on BaF2 host material and introduced the Tm3+ (activator) 5d–4f vacuum ultraviolet (VUV) luminescence center to suppress the STE luminescence. Tm:BaF2 single crystals were successfully grown by the micro-pulling-down (µ-PD) method with up to 10 mol % of Tm. The STE emission intensity decreased with increasing Tm concentration. Tm3+ 5d–4f emission was observed while cross-luminescence was decreased at higher Tm concentrations.
Microjoule Pulses from a High-Efficient Ytterbium-Doped Yttrium Aluminum Garnet Chirped-Pulse Oscillator
Authors: Xue Yinghong , Uemura Sadao , Torizuka Kenji
Published: February 2010

Employing a chirped-pulse-oscillator scheme, we have demonstrated a passively mode-locked Yb:Y3Al5O12 (Yb:YAG) bulk laser that delivers a total pulse energy of 2.07 µJ. The thermal lens effect of the Yb:YAG crystal was measured under lasing and non-lasing conditions. A maximum continuous-wave output power of 32.0 W was obtained with a high conversion efficiency of 68.4%. An 8.2-MHz low-repetition-rate mode-locked laser was designed using a semiconductor saturable absorber mirror (SESAM) and a multiple-pass cavity (MPC). It generated chirped 2.04-ps pulses that could be potentially dechirped to a pulse duration of 1.0 ps.
Surface-Enhanced Raman Scattering Substrate Fabricated by Femtosecond Laser Induced Co-deposition of Silver Nanoparticles and Fluorescent Molecules
Authors: Zhou Zenghui , Xu Jian , He Fei , Liao Yang , Cheng Ya , Sugioka Koji , Midorikawa Katsumi
Published: February 2010

Surface-enhanced Raman scattering (SERS) substrate with embedded molecules was fabricated by femtosecond laser induced co-deposition. During the femtosecond laser irradiation, silver ions in the AgNO3 solution were reduced and co-deposited on the slip surface together with organic molecules as SERS substrates. Raman scattering of the embedded molecules at the interstices of nanoparticles was strongly enhanced due to the localized electromagnetic field and the fluorescence was partly quenched. The enhanced Raman/fluorescence ratio makes it possible to distinguish the Raman signal from fluorescence for fluorescent samples at a high concentration. The fabricated SERS substrate can be used for the detection of specific biomolecules with high sensitivity.
Controllable Magnetization Processes Induced by Nucleation Sites in Permalloy Rings
Authors: Chen Ying-Jiun , Hsu Chia-Jung , Liao Chun-Neng , Huang Hao-Ting , Lee Chiun-Peng , Chiu Yi-Hsun , Tung Tzu-Yun , Lai Mei-Feng
Published: February 2010

Different arrangements of notches as nucleation sites are demonstrated experimentally and numerically to effectively control the magnetization processes of permalloy rings. In the ring with notches at the same side with respect to field direction, two same-helicity vortex domain walls in the onion state lead to two-step switching going through flux-closure state; in the ring with diagonal notches two opposite-helicity vortex domain walls lead to one-step switching skipping flux-closure state. The switching processes are repeatable in contrast to rings without notches where helicites of two vortex domain walls are random so the switching processes can not be controlled.
Superconductivity of FeSe0.5Te0.5Thin Films Grown by Pulsed Laser Deposition
Authors: Imai Yoshinori , Tanaka Ryo , Akiike Takanori , Hanawa Masafumi , Tsukada Ichiro , Maeda Atsutaka
Published: February 2010

FeSe0.5Te0.5thin films with a PbO-type structure are successfully grown on MgO(100) and LaSrAlO4(001) substrates from FeSe0.5Te0.5or FeSe0.5Te0.75polycrystalline targets by pulsed laser deposition. The film deposited on the MgO substrate (film thickness: ∼55 nm) shows superconductivity at 10.6 K (onset) and 9.2 K (zero resistivity). On the other hand, the film deposited on the LaSrAlO4substrate (film thickness: ∼250 nm) exhibits superconductivity at 5.4 K (onset) and 2.7 K (zero resistivity). This suggests the strong effect of substrate materials and/or thec-axis length on the superconducting properties of FeSe0.5Te0.5thin films.
Electron Emission from Cross-Sectional Surface of Porous Si on Glass Substrate
Authors: Higa Katsuya
Published: February 2010

The measurement of electron emission from the cross-sectional surface of porous Si layer on a glass substrate is demonstrated. The porous Si is formed by anodization, and subsequently bonded on a glass substrate with an Al electrode by anodic bonding. The electron emission device structure is composed of a Au electrode, a porous Si layer, and a glass substrate with an Al electrode. This structure is cut into two pieces during the formation of the cross-sectional surface of porous Si. The measurement of electron emission is carried out using a diode configuration in a vacuum chamber. A collector is placed close to the cross-sectional surface of porous Si. The negative voltages are applied at the Au electrode and electron emission from the cross-sectional surface of porous Si layer occurs. The characteristics of emission current are measured using the variation of applied negative voltage, the stability of electron emission, and the change in location of the Au electrode at the edge of the cross section of porous Si layer.
Minimization of Gate-Induced Drain Leakage by Controlling Gate Underlap Length for Low-Standby-Power Operation of 20-nm-Level Four-Terminal Silicon-on-Insulator Fin-Shaped Field Effect Transistor
Authors: Cho Seongjae , O'uchi Shinichi , Endo Kazuhiko , Matsukawa Takashi , Sakamoto Kunihiro , Liu Yongxun , Park Byung-Gook , Masahara Meishoku
Published: February 2010

Recently, gate-induced drain leakage (GIDL) has become a crucial factor of current characteristics as junction doping concentration becomes more abruptly graded owing to device scaling. It should be effectively suppressed for the low-standby-power operation of ultra small metal–oxide–semiconductor field effect transistor (MOSFET) devices. In this work, the appropriate underlap length range for the effective minimization of GIDL in 20-nm-level four-terminal (4-T) fin-shaped FET (FinFET) on silicon-on-insulator (SOI) is established. In order to identify the effect of underlap length on GIDL more precisely, the source and drain (S/D) junction doping profile and the majority/minority carrier lifetimes have been extracted by the measurement of a p–n junction test element group (TEG). The TEG was fabricated under the same process conditions that were used in forming the S/D junctions of 100-nm-level 4-T SOI FinFET in our previous research. The GIDL component in the off-state current is investigated with underlap length variation along with the inspection of basic current characteristics. For low-standby-power operation, an underlap junction is more desirable than an overlap junction, and the underlap length should be at least 10 nm to suppress GIDL effectively.
Influence of Effective Fixed Charges on Short-Channel Effects in SiC Metal–Oxide–Semiconductor Field-Effect Transistors
Authors: Noborio Masato , Suda Jun , Kimoto Tsunenobu
Published: February 2010

Influence of effective fixed charges, which are located near the metal–oxide–semiconductor (MOS) interface, on short-channel effects in 4H-SiC MOS field-effect transistors (FETs) has been investigated. The relationship between the threshold voltage and the channel length was theoretically calculated by using an original charge-share model, which takes the effective fixed charges into account. As a result, it was revealed that the effective fixed charges, which are attributed to electron trapping at the interface states, affect the relationship. The threshold voltage is decreased by reducing the channel length in the relatively-long channel region when the effective fixed charges exist. The theoretical relationship between the threshold voltage and the channel length calculated by using the proposed model agrees very well with the experimental results.
Combined Microfluidic–Eectric Diffused Mixing of Living Cells in Continuous Flow
Authors: Wang Ming-Wen
Published: February 2010

The mixing process is a crucially important stage in the operation of biological and chemical microfluidic devices. If the mixing is inadequate, reactants do not fully interact with each other, and the device may not operate properly. This paper describes a simplified microfluidic mixer (different from a chaotic mixer) which can uniformly mix a buffer solution with living cells by applying an AC electric charge. Diffusion of the living cells into the buffer solution occurs rapidly following the interface of the flow stream with the electric charge; no further agitating step is needed. To accomplish this, an asymmetric pair of electrodes was integrated at the inlets of the buffer solution and the cells fluid. When the buffer solution and the cells fluid were introduced into one flow path, they remained limited to that flow stream. When the electrodes were charged, however, the cells in a short distance were efficiently moved into the solution flow, and the original fluids were mixed. The mixing efficiency depends on the polarizability of the cells, and this in turn is governed by the dielectric properties of the cells, the medium, and the solvent. This micro device, capable of efficiently mixing living cells with a buffer solution, may potentially allow biological mixing to be done outside of hospitals, in facilities without biological analyzing instruments.
Liquid Crystal Device with Nanopatterned Indium–Zinc-Oxide Layer
Authors: Kim Hyun Jin , Lee Jong Geol , Kim Hyun Gi , Choi Suk-Won , Kim Sung Soo
Published: February 2010

Nanoscale grating patterns with indium–zinc-oxide (IZO) layer have been successfully fabricated by ultraviolet (UV) nanoimprinting technique and sputter deposition process. Nanoscale groove prepared here can play important roles as alignment layers as well as conducting electrodes. Performance for LC alignment was tested by evaluating order parameter. A preliminary version of twist nematic (TN) LC cell with the nanopattern coated IZO was also fabricated and evaluated.
Monte Carlo Analysis of Base Transit Times of InP/GaInAs Heterojunction Bipolar Transistors with Ultrathin Graded Bases
Authors: Uesawa Takafumi , Yamada Masayuki , Miyamoto Yasuyuki , Furuya Kazuhito
Published: February 2010

The base transit times of an InP/GaInAs heterojunction bipolar transistor (HBT) with an ultrathin and heavily doped base are investigated by carrying out a Monte Carlo (MC) simulation. The acceleration of electrons due to a conduction-band discontinuity between the emitter and base is taken into consideration. Scattering caused by the spontaneous emission of hole plasmons considerably increases the base transit time even when the thickness of the base is 20 nm. Band-gap grading in the base effectively sweeps slow electrons into the collector, and the increase in the base transit time is partially suppressed. The MC simulation shows that when the band-gap grading is just twice the thermal energy, the transit time of the 20-nm-thick base decreases by 40%.
Formation of Ge Nanosheets Decorated Hierarchical ZnSe/GeSe Nanowire Heterostructures
Authors: Xie Qingqing , Wang Chunrui , Xu Xiaofeng , Liu Jian , Zhang Jing
Published: February 2010

We report on the fabrication of Ge nanosheets decorated ZnSe/GeSe hierarchical heterostructure nanowires via a simple one-step thermal evaporation of ZnSe and Ge powder. A typical Ge nanosheets decorated ZnSe/GeSe hierarchical heterostructure nanowire consists of ZnSe/GeSe bi-coaxial nanowire, secondary nanostructures of GeSe nanobrushes are grown on the primary ZnSe/GeSe bi-coaxial nanowire, Ge nanosheets are decorated on the GeSe nanobrushes. The possible growth mechanism of the novel hierarchical nanowire heterostructures is discussed. In addition, the vibrating properties of Ge decorated ZnSe/GeSe hierarchical heterostructure nanowires are studied by using Raman spectroscopy.
Site-Selective Cutting of Carbon Nanotubes by Laser Heated Silicon Tip
Authors: Tarun Alvarado , Hayazawa Norihiko , Kawata Satoshi
Published: February 2010

We demonstrate cutting of carbon nanotube using the heat generated from the absorbed electromagnetic field at the tip apex of silicon tip that is transferred to the sample by conduction. By varying the incident laser power, the temperature can be controlled and approximated by spectrally resolving the shifted Si–Si Raman peak coupled with the joule heating generated at the tip apex. Topographic imaging and far-field Raman intensity mapping before and after cutting of carbon nanotubes were simultaneously obtained to verify the extent of damage. The technique presented can be used for thermal characterization of various materials requiring nanoscale heat source.
Effects of Nanoscaled Tin-Doped Indium Oxide on the Image Sticking Property of Liquid Crystal Cells
Authors: Liang Bau-Jy , Liu Don-Gey , Shie Wun-Yi , Huang Sy-Ruen
Published: February 2010

Unusual residual time of image sticking under high-voltage electrostatic discharge (ESD) stress on liquid crystal (LC) cells has been observed. It was found that nanoscaled conductive particles doped in LC cells can significantly reduce the residual time of image sticking and the breakdown voltage of the LC cells. This finding can help to protect the doped cells from the attacks of ESD and thus to improve their displaying performance and reliability. In this study, nanoscaled tin-doped indium oxide (ITO) powders were uniformly mixed with high-resistance LC to form a suspension solution. In order to investigate other effects of ITO particles on the LC at high and low voltages, optical and electrical characteristics were compared for the doped cells and those samples without intentional doping. According to the measurement results, it is interesting to find that, except the breakdown characteristic, no other properties in the doped samples were changed with respect to the displaying functions under normal operational voltage.
Performance of Zero-Schottky-Barrier and Doped Contacts Single and Double Walled Carbon Nanotube Transistors
Authors: Wahab Md. Abdul , Alam Khairul
Published: February 2010

Atomistic quantum simulation is performed to compare the performance of single walled (SW) and double walled (DW) carbon nanotube field effect transistors (CNTFETs) with two different types of contacts: zero-Schottky-barrier (SB) contacts and doped (DP) contacts. Both the DW and SW CNTFETs have better performance with doped contacts. The conduction band under the gate region is pushed down below the source Fermi level when the applied gate bias is ≥ E
g/2. Beyond this gate voltage, the current in SB CNTFETs becomes almost constant. This does not happen to the doped contacts devices and they have better on-state performance. With the same type of contacts, the SW and DW CNTFETs exhibit similar I–V characteristics. However, the switching delay and the unity current gain frequency are much better in DW CNTFETs for both types of contacts. The better switching performance of DW CNTFETs results from the smaller gate capacitance.
Bias Potential for Tip–Plane Systems in Kelvin Probe Force Microscopy Imaging of Non-uniform Surface Potential Distributions
Authors: Sajewicz Krzysztof , Krok Franciszek , Konior Jerzy
Published: February 2010

The bias potential,Vbias, is the key quantity for the Kelvin probe force microscopy (KPFM) measurements and interpretation. Using an efficient method for electrostatic force determination,Vbiashas been calculated for tip–plane systems, with realistic tip geometry and for non-uniform potential distributions on the plane. The considered potential distributions on the plane include a potential step, a quadratic potential island, and two quadratic potential islands with varying separation.Vbiashas been evaluated along three different schemes, i.e., from the minimization of electrostatic force, from the force gradient, and from the integral formula. We have studiedVbiasas a function of tip–surface distance, island size, vibration amplitude, and tip sharpness radius (the so called nanotip). We have found that there are substantial differences between the gradient and integral schemes forVbiasevaluation. We have determined that the nanotip presence favors an accurate potential mapping, particularly for small potential islands. The implications of the obtained results for KPFM method are also discussed.
Studies of Thermal Conductivity of Gd2Zr2O7 and Diamond-Like Carbon Films and the Interfacial Effect
Authors: Kang Jun-Gu , Hong Kyong-Soo , Yang Ho-Soon
Published: February 2010

Gadolinium zirconium oxide (Gd2Zr2O7) films and diamond-like carbon (DLC) films were prepared by RF-magnetron sputtering and an ion gun method, respectively. To study the thermal conductivity of these films, we used the 3ω and time-domain thermoreflectance (TDTR) methods. The thermal conductivity showed a film thickness dependence for the 3ω method, and this dependence is described as an interfacial effect by considering heat penetration depth in the measurement. The obtained thermal conductivities of the Gd2Zr2O7 and DLC films, independent of the interfacial effect, are 1.6 and 2.5 W m-1 K-1, respectively. The thermal conductivity of the Gd2Zr2O7 films showed no significant thickness dependence for the TDTR method. The conductivities of Gd2Zr2O7 1.6–1.8 W m-1 K-1 obtained by the TDTR method were close to the thermal conductivity of the Gd2Zr2O7 films, independent of the interfacial thermal effect observed in the 3ω method.
Propagation of a Light-Emitting Wave-Front in a Fine Tube Positive Column Discharge
Authors: Jeong Jong-Mun , Kim Jung-Hyun , Hwang Hachung , Jin Dong-Jun , Koo Je-Huan , Choi Eun-Ha , Verboncoeur John P. , Uhm Han Sup , Cho Guangsup
Published: February 2010

The propagation velocity of a light-emitting wave-front is observed to be u
p∼2×10+5 m/s before Townsend breakdown and u
p∼5×10+6 m/s after Townsend breakdown along a discharge tube of inner diameter r
o∼1.2 mm and length of 900 mm relevant to liquid crystal display television backlighting. Before Townsend breakdown, the origin of this wave is the ambipolar diffusion of plasma flux with the propagation speed u
p∝D
a/r
o for the plasma bounded by the radius r
o with the diffusion coefficient D
a along the positive column. After Townsend breakdown, the light-emitting wave-front propagates with the electron plasma wave generated by the pulses of driving voltage. The electron plasma wave propagates such a long distance along the tube without damping due to the effect of localized plasma generation by electron impact ionization collisions. The propagation velocity is described by u
p∼2u
e
2/u
d, which is larger than the electron thermal velocity u
e as well as the electron drift velocity u
d.
Comparison of Properties of Atmospheric-Pressure Radio Frequency He/SF6/O2and He/CF4/O2Discharges
Authors: Kimura Takashi , Tanahashi Hiroki
Published: February 2010

Electrical and optical measurements of atmospheric-pressure radio frequency (13.56 MHz) He/SF6/O2and He/CF4/O2discharges are carried out by changing the mixture ratio of a fluoride compound gas to oxygen, where the fraction of He is fixed at 99.5%. Such discharges are produced between two planar electrodes of 40 mmφ at a gap length of 1.0 or 1.44 mm in the dissipated power range from 30 to 170 W. The phase difference between applied voltage and current in the He/SF6/O2discharges is approximately 20–30°, whereas that in the He/CF4/O2discharges is approximately 50–60°. The density of fluorine atoms in such discharges, which should be estimated by actinometry, depends on the mixture ratio of the fluorine compound gas to oxygen. The maximum density is observed when the ratios of the oxygen fraction to the sum of the oxygen and fluoride compound gas fractions are approximately 0.3–0.5 for the He/SF6/O2discharges and 0.2 for the He/CF4/O2discharges. The density of fluorine atoms in such discharges is on the order of 1014cm-3. In addition, the results obtained by ozone titration are compared with the density of fluorine atoms in the plasma, which is estimated by actinometry.
Investigating Effect of Conditioner Aggressiveness on Removal Rate during Interlayer Dielectric Chemical Mechanical Planarization through Confocal Microscopy and Dual Emission Ultraviolet-Enhanced Fluorescence Imaging
Authors: Sun Ting , Borucki Len , Zhuang Yun , Sampurno Yasa , Sudargho Fransisca , Wei Xiaomin , Anjur Sriram , Philipossian Ara
Published: February 2010

The effect of conditioner aggressiveness is investigated in interlayer dielectric polishing on three types of pad. A method using confocal microscopy is used to analyze the effect of conditioner aggressiveness on pad–wafer contact. Results show that a more aggressive conditioner produces a higher interlayer dielectric polishing rate while at the same time a pad surface with fewer contacting summits and less contact area. It is found that the ratio of the contacting summit density to the contact area fraction is more important than either parameter measured separately since the ratio determines the mean real contact pressure. Modeling results based on contact area measurements agree well with experimental results. Moreover, it is found that a more aggressive disc also generates a thicker slurry film at the pad–wafer interface. This is in agreement with our general findings regarding pad asperity height distribution obtained using confocal microscopy.
Ge2Sb2Te5Phase Change Memory Cell Featuring Platinum Tapered Heating Electrode For Low-Voltage Operation
Authors: Lv Shilong , Song Zhitang , Liu Yan , Feng Songlin
Published: February 2010

Phase change random access memory (PC-RAM) with a Pt tapered heating electrode (Pt-THE), which was fabricated using a focus ion beam (FIB), was investigated. Compared with the tungsten electrode, the Pt-THE facilitates the temperature rise in phase change material, which causes the decrease of reset voltage from 3.5 to 2.4 V. The programming region of the cell with Pt-THE is smaller than that of the cell with a cylindrical tungsten heating electrode. The improved performance of the PC-RAM with a Pt-THE is attributed to the higher resistivity and lower thermal conductivity of the Pt electrode, and the reduction of the programming region, which is also verified by thermal simulation.