bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of NiSi-Silicided p+n Shallow Junctions by BF2
+ Implantation into/through Silicide and Rapid Thermal Annealing
Authors: Wang Chao-Chun , Wu You-Kuo , Wu Wei-Hao , Chen Mao-Chieh
Published: July 2005

NiSi-silicided p+n shallow junctions are fabricated by BF2
+ implantation into/through a thin NiSi silicide layer, followed by rapid thermal annealing (RTA). The NiSi film starts to show agglomeration after RTA at 650°C, which may result in the formation of discontinuous islands at higher temperatures. The incorporation of fluorine atoms in the NiSi film can retard the film agglomeration, making the film stable up to 800°C. A forward ideality factor very close to unity and a reverse bias current density of 0.6 nA/cm2 can be attained for the NiSi(31 nm)/p+n junctions fabricated by BF2
+ implantation to a dose of 5×1015 cm-2 at 35 keV, followed by RTA for 30 s at 650°C; the junction formed is about 37 nm measured from the NiSi/Si interface. Activation energy measurement shows that the reverse bias junction currents are dominated by the diffusion current, which indicates that most of the implanted damage can be recovered by RTA at temperatures as low as 650°C.
Development of a Dual Inductively Coupled Plasma Source for Direct and Remote Plasma Generation in a Reactor
Authors: Uhm Saehoon , Lee Kyung Ho , Chang Hong Young , Chung Chin Wook
Published: July 2005

A dual inductively coupled plasma (ICP) system consists of a remote ICP reactor with small volume and a main ICP reactor with a substrate. Two ICP antennas were connected in parallel and a variable capacitor (C
var) was installed in series at the end of the main ICP antenna. By adjusting the capacitance of the variable capacitor, the plasma densities in the remote region and the main region are controlled. For the remote region, the plasma was considerably changed such that it had high density and the electron temperature was higher than that in the main region because of its small volume. As such, reactive species in the remote region appeared to be effectively generated. The dual ICP system was applied to Si etching. It was observed that Si etch rate increased by 20% as the plasma density in the remote region increased, even though the plasma density in the main region decreased. This might be understood by considering the role of the remote ICP as a radical generator.
Enhancement of Surface Potential Buildup and Decay of Tris(8-quinolinato)aluminum Film Deposited on Ultraviolet/Ozone-Treated Gold Electrodes
Authors: Kajimoto Norifumi , Muhamad Muhamad Rasat , Rahman Saadah Abdul , Manaka Takaaki , Iwamoto Mitsumasa
Published: July 2005

The enhancement of the surface potential of tris(8-quinolinato)aluminum (Alq3) film deposited on ultraviolet (UV)/ozone-treated gold electrodes was confirmed by surface potential measurement, and the ordering of molecular dipoles was suggested. The enhanced surface potential of the order of 10 V decayed rapidly by photoirradiation, due to molecular dipole disordering, but a surface potential of 100–400 mV remained. Interestingly, this remaining surface potential of Alq3 on the UV/ozone-treated gold electrode was always smaller than that of Alq3 film on an untreated gold electrode. It was concluded that the UV/ozone treatment is effective in decreasing the density of surface states at the Alq3-metal interface as well as for the enhancement of molecular dipole ordering.
Simultaneous Measurement of Phase Retardation and Fast-Axis Angle of Phase Retardation Plate
Authors: Kuo Wen-Chuan , Liao Kuo-Yu , Jan Gwo-Jen , Teng Hui-Kang , Chou Chien
Published: July 2005

A phase retardation plate, such as a quarter-wave plate, is able to control the state of polarization. Thus, a precise simultaneous determination of phase delay between two eigen-polarization states and its fast-axis angle is essential to the performance of the phase retardation plate to control the state of polarization. Consequently, the measurement of the two-dimensional spatiotemporal distribution of phase retardation and the fast-axis angle become crucial when a large-area of phase retardation plate, such as that for a liquid crystal display, is characterized, due to the inhomogeneity of the retardation plate. In order to measure the linear birefringence parameters, phase retardation and fast-axis angle at the same time, a novel polarized optical heterodyne interferometer is developed, with which the parameters of a quarter-wave plate are successfully measured and verified. The features of this device are (1) a common-path configuration, (2) measurement independent of laser intensity, and (3) the capability of simultaneously determining the spatiotemporal distributions of phase retardation and fast-axis angle of a retardation plate.
Spectral Analysis of Ultraweak Chemiluminescence from Kidney Bean Leaf Infested with Tetranychus Kanzawai Kishida
Authors: Kawabata Ryuzou , Miike Tohru , Okabe Hirotaka , Uefune Masayoshi , Takabayashi Junji , Takagi Masami , Kai Shoichi
Published: July 2005

We performed the spectral analysis of ultraweak-photon emissions from kidney bean leaves infested by the kanzawa spider mite,Tetranychus kanzawaiKishida (Acari: Tetranychidae). We also measured the spectrum of photon emissions from artificially wounded leaves, and compared the result with spectral data obtained from the mite-infested leaves. Photon emissions from both the mite-infested and wounded leaves primarily consisted of wavelengths ranging from 500 to 700 nm, and photon intensity at these wavelengths increased steadily after perturbation. In contrast, photon intensity of the mite-infested leaves at 300–400 nm exhibited only differential changes; it began increasing at 20 h, and showed two peaks at 72 and 120 h. We previously reported that photon emissions from infested leaves might be the result of both insect damage and plant self-protection. Plant defensive responses, such as herbivore-induced plant volatiles (HIPV), are induced by insect elicitors via insect damage. Therefore, photon intensity at 500–700 nm might be related to direct injury (physiological stress), while photon intensity at 300–400 nm may signify a physiological (biochemical)-action-related defensive response.
Oxidation Patterning of GaAs by Nanoelectrode Lithography
Authors: Yokoo Atsushi , Sasaki Satoshi
Published: July 2005

Nanoelectrode lithography, which transfers patterns from a nanoelectrode to a target via an electrochemical reaction, is employed for patterning GaAs. Gallium oxide and arsenic oxide are produced by the anodic oxidation of GaAs. A-400-nm pitch line and space (L/S) pattern and a closely packed hexagonal pattern with a 500 nm pitch are successfully transferred. For the 400-nm-pitch L/S pattern, a patterned area of 6×8 mm2 is obtained with a reaction time of 30 s. The fabricated pattern can be directly used as an etching mask. Structures with depths of approximately 70 and 10 nm are obtained by wet and dry etchings, respectively. In addition, it is confirmed that multiple patterning is also possible on a GaAs substrate.
Fabrication of Quantum Well Infrared Photodetectors Using Chemically Wet-Etched Grid Nanostructures
Authors: Jeong Heejun
Published: July 2005

Quantum well infrared photodetectors were fabricated using a chemical wet etching method, defined on a GaAs/AlGaAs heterostructure. These devices utilized grid nanostructures for effective light coupling through the diffraction effect. By reducing grid widths close to the depletion of the quantum well, we observed a systematic increase in the normalized responsivity of the photodetectors, as a possible signature of the quantum size effect, with blue shift. We also achieved precise control of grid widths through wet etching that does not require an expensive processing instrument.
Forward-Biased Cadmium Telluride Detectors with High-Energy Pulse X-ray Sources
Authors: Kitazawa So , Kamimura Hiroshi , Nukaga Jun , Takagi Hiroyuki , Satoh Katsutoshi
Published: July 2005

Forward-biased Schottky CdTe detectors (In/CdTe/Pt) have been investigated with an electron linear accelerator as an X-ray source, in order to suppress the polarization effect. The forward-biased detectors which have considerably large leakage currents show no gradual decrease in signals with time due to the polarization, while the reverse-biased detectors show a gradual decrease. Moreover, the outputs in the forward-biased state are much larger than those in the reverse-biased state.
Evaluation of Front-Opening Unified Pod with Attached UV/Photocatalyst Cleaning Unit
Authors: Suzuki Masato , Tabei Tetsuo , Yokoyama Shin , Miyamoto Kazuhisa , Wada Takeo , Fujii Toshiaki
Published: July 2005

We have developed a wafer box for 300 mm Si wafers with an attached cleaning system for organic contamination gas. The front-opening unified pod (FOUP) is modified to be attached to the UV/photocatalyst cleaning unit. It is found that the reliability degradation of metal oxide semiconductor (MOS) capacitors fabricated using wafers stored in the FOUP with the cleaning unit is suppressed compared with that of MOS capacitors fabricated using wafers stored in the FOUP without the cleaning unit.
Effects of Non-Axisymmetric Magnetization Force on Natural Convection of Water at Various Off-Centered Positions in Superconducting Magnet: Numerical Computation Studies
Authors: Maki Syou , Ataka Mitsuo
Published: July 2005

Hydrodynamic equations including the effect of magnetization force were solved numerically to determine the natural convection of water in a shallow, cylindrical vessel set up at off-centered positions in a superconducting magnet. The magnetization convection varied considerably when the vessel location became eccentric, influenced by the non-axisymmetric distribution of magnetization force. A proper way of installing a vessel in the magnet is discussed to make the best use of magnetization force.
Thermocapillary Effect of a Liquid Plug in Transient Temperature Fields
Authors: Nguyen Nam-Trung , Huang Xiaoyang
Published: July 2005

In this paper we present the theoretical and experimental results of thermocapillary effects of liquid plugs in a long capillary, which is exposed to a transient temperature gradient. A one-dimensional analytical model is formulated for the dynamic behavior of a liquid droplet, which is driven by the thermocapillary effect under a transient temperature field. The thermocapillary actuation concept can be used for liquid transport in microfluidics. In microfluidic applications, the temperature field is often induced by the activation of integrated heaters. The generated temperature field and temperature gradient drive a liquid droplet according to the temperature-dependent surface tension. In the initial stage, the transient temperature gradient spreads in the capillary wall much slower than the droplet itself, and thus leads to an interesting behavior of droplet motion as described in this paper. Experiments were carried out for liquid droplets with different viscosities in long glass capillaries with different radii. The capillaries are exposed to a resistive heater at one of its ends. The analytically predicted behavior of the droplet motion agrees qualitatively well with the measurement.
Analyses of DNA Base Sequences for Eukaryotes in Terms of Power Spectrum Method
Authors: Isohata Yasuhiko , Hayashi Masaki
Published: July 2005

By adopting a power spectrum method we have analyzed long-range correlations in the gene base sequences, exons and introns for five or six eukaryote species. As a measure of the long-range correlations, we have used an exponent α in 1/fα, which is an approximation of a power spectrum in a low-frequency region. We have analyzed frequency distributions of α and the dependence of its average values <α> on the sequence length for the five or six species, paying particular attention to the species dependence. We have shown that long-range correlations have been formed mainly due to the intron's elongation as well as by the sequence structures of introns acquired over the course of evolution.
Fine Tuning of the Sizes of FePt Nanoparticles
Authors: Momose Satoru , Kodama Hiroyoshi , Uzumaki Takuya , Tanaka Atsushi
Published: July 2005

Fine tuning of the sizes of FePt nanoparticles has been realized by a simple modification of a solution phase synthesis, which consists of the decomposition of Fe(CO)5 and the reduction of Pt(acac)2. The key method used to control the particle size is the use of surfactants, and only a change in their amount is required to vary the average sizes of the FePt nanoparticles from 2 to above 4 nm. The resultant nanoparticle volume is proportional to the surfactant amount; this makes the synthesis of FePt nanoparticles of desired sizes possible.
Fabrication of Dense Carbon Nanotube Films Using Microwave Plasma-Enhanced Chemical Vapor Deposition
Authors: Hiramatsu Mineo , Taniguchi Masaki , Nagao Hidetoshi , Ando Yoshinori , Hori Masaru
Published: July 2005

Carbon nanotubes (CNTs) were synthesized using microwave plasma-enhanced chemical vapor deposition. Co nanoparticles as catalyst were prepared using excimer laser ablation. Vertically aligned, dense CNT films were grown successfully on a Co-catalyzed Si substrate with a TiN buffer layer. The density of CNTs with a diameter of approximately 6 nm was controllable by changing the deposition time of Co catalytic nanoparticles prior to nanotube growth. CNTs were grown rapidly during the first 3 min of growth, then the growth rate of CNTs decreased markedly. At the early stage of growth, the CNTs grew at an extremely high rate of 300 nm/s.
Fabrication of Isolated Alloy Nanoballs and Nanowires Using Centrifugal Force
Authors: Kuo Chin-Guo , Chao Chuen-Guang
Published: July 2005

Lead–bismuth alloy nanoballs and nanowires were fabricated using a process based on centrifugal forces. An AAO template with a molten Pb–Bi alloy was sealed in a titanium tube in vacuum at a pressure of 10-6 Torr, controlled using a molecular turbo-pump. When various centrifugal forces were generated in the titanium tube, nanoscalar alloy balls and wires were formed. During centrifugation, the sealed titanium tube could prevente the oxidation of the Pb–Bi alloy at the interface between the molten alloy and the AAO template. The repulsive force between the nanotube and the molten alloy, and the force applied to the molten alloy inside the AAO template were calculated using the surface tension of the ultrafine tube and centrifugal forces.
Theoretical Investigation of Dielectric Constant and Elastic Modulus of Two-Dimensional Periodic Porous Silica Films with Elliptical Cylindrical Pores
Authors: Miyoshi Hidenori , Matsuo Hisanori , Tanaka Hirofumi , Yamada Kazuhiro , Oku Yoshiaki , Takada Syozo , Hata Nobuhiro , Kikkawa Takamaro
Published: July 2005

The effects of film shrinkage during the thermal curing of two-dimensional periodic porous silica films on the relative dielectric constant k with respect to the vacuum value and the relative elastic modulus E with respect to the skeletal (pore-wall) value E
w were investigated by theoretical calculations. Two extreme models of the film thickness shrinkage were assumed in the calculation: the constant porosity model and the constant wall volume model. It was found that E/E
w decreased more markedly upon film thickness shrinkage in the constant porosity model than it did in the constant wall volume model. The calculated results were confirmed by the experimental data together with the elliptical cylindrical pore shape. It is shown that the film shrinkage of ultralow-k porous silica films must be suppressed for achieving the higher elastic modulus while keeping the k value constant.
Theoretical Investigation into Effects of Pore Size and Pore Position Distributions on Dielectric Constant and Elastic Modulus of Two-Dimensional Periodic Porous Silica Films
Authors: Miyoshi Hidenori , Hata Nobuhiro , Kikkawa Takamaro
Published: July 2005

The effects of the pore size distribution (psd) and pore position distribution (ppd) of two-dimensional (2D) periodic porous silica films on dielectric constant (k) and elastic modulus (E) were investigated by theoretical calculations. It was found that such porous silica films with a wider psd or a wider ppd show lower E value than 2D hexagonal periodic porous silica films with an identical pore size. Careful control of pore structure is necessary for obtaining ultralow-k porous silica films with a high E.
Defects Induced by Carbon Contamination in Low-Temperature Epitaxial Silicon Films Grown with Monosilane
Authors: Sato Shin'ya , Mizushima Ichiro , Miyano Kiyotaka , Sato Tsutomu , Nakamura Shin'ichi , Tsunashima Yoshitaka , Arikado Tsunetoshi , Uchitomi Naotaka
Published: July 2005

The structures of the defects induced by carbon contamination in epitaxial silicon films grown with monosilane (SiH4) on silicon substrates were investigated. A new formation mechanism of defects associated with carbon in silicon epitaxial growth processes is proposed. The carbon contaminants were introduced prior to the growth by chemical vapor deposition (CVD), where the growth chamber was intentionally contaminated with organic materials. The carbon contaminant concentration was changed by adjusting the annealing conditions at temperatures ranging from 900°C to 1100°C. Silicon epitaxial films were grown by CVD at a temperature of 700°C. In this experiment, we found that pits were formed as dominant surface defects under the condition of a relatively low carbon concentration of less than 4.5×1013 cm-2, while mound defects were formed at a carbon concentration of more than 4.5×1013 cm-2. These defects can be explained by the formation of silicon carbide (SiC) islands resulting from the carbon contamination.
Oxidation of InAlAs and Its Application to Gate Insulator of InAlAs/InGaAs Metal Oxide Semiconductor High Electron Mobility Transistor
Authors: Paul Narayan Chandra , Nakamura Kazuki , Seto Hiroki , Iiyama Koichi , Takamiya Saburo
Published: July 2005

InAlAs was oxidized by UV and ozone process. Nanometer-order thin-oxide layers were generated in proportion to the square root of the process period, although their correlation with the period is poor compared with that of InGaAs. Oxidation initially decreased photoluminescence intensity from the InAlAs surface and then gradually increased it when the process period exceeded 15 min until it reached 4 h (crystallographic-order degradation followed by recovery). Plasma nitridation of InAlAs exhibited a gradual and monotonic decrease in photoluminescence intensity. Lattice-matched InAlAs/InGaAs metal–oxide–semiconductor high electron mobility transistors were fabricated utilizing gate oxide layers which were formed by 4 h oxidation. A transconductance of 200 mS/mm was obtained using a 1.5-µm-gate-length device, in a high-forward-gate-bias region although hysteresis was observed in the current–voltage curve.
Rapid and Uniform SiO2 Film Growth on 4 inch Si Wafer Using 100%-O3 Gas
Authors: Nishiguchi Tetsuya , Sato Yosuke , Nonaka Hidehiko , Ichimura Shingo , Noyori Takeshi , Morikawa Yoshiki , Kekura Mitsuru , Nihei Yoshimasa
Published: July 2005

We have developed a lamp-heated cold-wall chamber that can process a large Si wafer using a highly concentrated (>90 vol.%) ozone gas to achieve rapid and uniform oxidation at a lower temperature than that used in conventional thermal oxidation. Uniform SiO2 formation with a film thickness uniformity of within 0.2 nm was achieved. The SiO2 growth rate, however, was not markedly accelerated compared with that achieved using conventional low (i.e., 10 vol.%)-concentration O3 gas. This was considered to originate from the decomposition of O3 gas in the gas phase before arriving at a heated surface as determined from the local ozone concentration measurements we performed. By increasing gas flow velocity so as to reduce the area of the thermal boundary layer on the heated surface in which decomposition of O3 to molecular oxygen is enhanced, SiO2 growth rate was actually improved.
Studies of Effects of Adsorption of Silicon or Germanium on the Electronic States of (100) GaAs Surfaces
Authors: Miyamura Satoshi , Seto Hiroki , Inokuma Takao , Iiyama Koichi , Takamiya Saburo
Published: July 2005

The electronic states of both bare Ga-terminated and As-terminated (100)-(1×1) GaAs surfaces and the same surfaces with adsorbed Si or Ge were studied by molecular orbital calculations using small cluster models and the discrete variational Xα method. The most stable adsorption sites for Si and Ge are bridge sites on the (100)-GaAs surface, regardless of whether they are Ga- or As-terminated. When Si or Ge atoms are adsorbed, the density of the surface states in the forbidden band of the Ga or As surface layers markedly decreases. This suggests that both the Ga-terminated and As-terminated surfaces have a clear band gap when either Si or Ge are adsorbed on the surfaces. These adsorbates have states in the lower half of the band gap or in the valence band.
Cu(In,Al)S2 Thin Film Solar Cell
Authors: Inazu Takuya , Bhandari Ramesh Kumar , Kadowaki Yuji , Hashimoto Yoshio , Ito Kentaro
Published: July 2005

A Cu(In,Al)S2 thin film solar cell has exhibited good adhesion to Mo-coated glass and comparatively high efficiency. The sputter-deposited metallic precursor was sulfurized and then treated in a KCN solution to remove a Cu
x
S impurity phase and an excessive Al compound from the film surface. When the precursor layer was Cu-rich, the treated sulfide film could be used as an efficient absorber material. It had the same band gap as CuInS2. The spectral response of the cell was increased in a short wavelength range. The bottom region of the film was considered to consist of a Cu(In,Al)S2 alloy that enhanced the film adhesion to the Mo back contact. The film was analyzed using X-ray diffraction, electron probe microanalysis, scanning electron microscopy and field ion microscopy combined with focused ion beam technique.
Mechanism of Anomalous Behavior of Metal–Oxide–Semiconductor Capacitors Contaminated with Organic Molecules
Authors: Suzuki Masato , Yokoyama Shin
Published: July 2005

The influence of organic contamination on the characteristics of metal–oxide–semiconductor (MOS) capacitors is studied. An anomalous behavior of the capacitance in the inversion region is observed, i.e., the inversion capacitance for the organic-molecule-contaminated samples is substantially increased by the reverse bias stress and decreased after removing the stress. These phenomena are explained on the basis of the change in the response time of the minority carriers (electrons) in the inversion layer caused by the change in the Si/SiO2 interface trap density. Namely, the interface trap is generated by the bias stress for the organic-molecule-contaminated sample and it is self-healed after the removal of the stress. We measure the temperature dependence of this self-healing of the interface traps and the activation energy of ∼0.04 eV is obtained. On the basis of the results, we propose a model for the self-healing mechanism.
Interface Properties of Metal–Oxide–Semiconductor Structures on 4H-SiC{0001} and (1120) Formed by N2O Oxidation
Authors: Kimoto Tsunenobu , Kanzaki Yosuke , Noborio Masato , Kawano Hiroaki , Matsunami Hiroyuki
Published: July 2005

4H-SiC(0001), (0001), and (1120) have been directly oxidized by N2O at 1300°C, and metal–oxide–semiconductor (MOS) interfaces have been characterized. The interface state density has been significantly reduced by N2O oxidation on any face, compared to conventional wet O2 oxidation at 1150°C. Planar n-channel metal–oxide–semiconductor field-effect transistors (MOSFETs) fabricated on 4H-SiC(0001), (0001) and (1120) faces have shown effective channel mobilities of 26, 43, and 78 cm2/Vs, respectively. Secondary ion mass spectrometry analyses have revealed a clear pileup of nitrogen atoms near the MOS interface. The thickness of the interfacial transition layer can be decreased by N2O oxidation. The crystal face dependence of the interface structure is discussed. A simple consideration of chemistry indicates that NO, generated from the decomposition of N2O, may be a more efficient oxidant of carbon than O2.
Dependence of Oxide Pattern Density Variation on Motor Current Endpoint Detection during Shallow Trench Isolation Chemical Mechanical Planarization
Authors: Sorooshian Jamshid , Philipossian Ara , Stein David J. , Timon Robert P. , Hetherington Dale L.
Published: July 2005

In this study, we evaluate the limitations associated with variable shallow trench isolation (STI) oxide pattern densities for accurate motor current endpoint detection during chemical mechanical planarization (CMP). Results indicate that repeatable motor current endpoint detection can be achieved for STI wafers with oxide pattern density variations of up to 17.4%. Furthermore, results show that a dependence exists between the STI oxide pattern density variation and motor current endpoint success during polishing. According to the findings of this study, a suitable motor current endpoint detection system could yield successful termination points for STI polishing, as well as reduce the need for polishing reworks.
Development and Analysis of a High-Pressure Micro Jet Pad Conditioning System for Interlayer Dielectric Chemical Mechanical Planarization
Authors: Seike Yoshiyuki , DeNardis Darren , Sugiyama Masano , Miyachi Keiji , Doi Toshiro , Philipossian Ara
Published: July 2005

Conventional diamond disc pad conditioning methods employed in chemical mechanical planarization (CMP) have presented several problems for integrated circuit (IC) manufacturers. These include diamond wear, which reduces pad life, and diamond fracture, which causes the semiconductor devices to be scratched by loose diamond fragments. In order to attempt to overcome these problems, a high-pressure micro jet (HPMJ) conditioning system, in which pressurized ultra pure water (UPW) ranging from 3–30 MPa is sprayed on the pad surface, is proposed and developed. This study first analyzes the extent of the kinetic energy of water droplets ejecting from the HPMJ system and its utility in conditioning the pad surface. Subsequently, CMP is used to polish interlayer dielectric (ILD) films using both conventional diamond discs as well as HPMJ conditioning methods. Results, reported in the form of coefficient of friction (COF), removal rate, pad surface roughness and pad surface quality, highlight both the advantages as well as disadvantages of the HPMJ method compared to conventional conditioning schemes.
Characterization of Ultra Thin Oxynitride Formed by Radical Nitridation with Slot Plane Antenna Plasma
Authors: Sugawara Takuya , Matsuyama Seiji , Sasaki Masaru , Nakanishi Toshio , Murakawa Shigemi , Katsuki Jiro , Ozaki Shigenori , Tada Yoshihide , Ohta Tomohiro , Yamamoto Nobuhiko
Published: July 2005

We investigated the plasma nitridation mechanisms for an ultra-thin gate oxynitride (SiON) formation to extend the downscaling limit of equivalent oxide thickness (EOT). Using the slot plane antenna (SPA) plasma nitridation system, excellent gate SiON properties were obtained with low gate leakage and good carrier mobility down to less than 12 Å. From electrical and physical analysis results, the nitridation mechanism was discussed, which suggested that a control of oxygen partial pressure is important to achieve EOT reduction. A low electron temperature (T
e) process under high-pressure condition leads to improved G
m and NBTI performance, which indicates that the reduction of a plasma damage under nitridation processes improve the performance and reliability of ultra thin SiON film. With optimized nitridation processes, the mobility degradation of nMOSFET is only 8% at EOT=11 Å. The NBTI reliability of pMOSFET is improved by more than 1 order compared with a low-pressure, high T
e condition.
Modification of YBa2Cu3Oy Thin Films by Exposure to Argon Plasma and Ozone: A Structural Study
Authors: Mohamed Syed B. , Oyanagi Hiroyuki , Fukano Atsuyuki , Sato Hiroshi , Akoh Hiroshi
Published: July 2005

The effects of argon plasma bombardment and subsequent heat treatments on the structure of YBa2Cu3O
y
thin films were studied. We find that the argon plasma processing modifies the yttrium composition through the formation of Y2O3 islands (serving as an yttrium reservoir) and solid-state diffusion. The scanning electron microscopy (SEM) images show that the argon plasma bombardment accelerates the growth of Y2O3 islands which are thinned and washed away during the subsequent annealing in vacuum. Complimentary techniques (X-ray diffraction and X-ray absorption spectroscopy) show that the structural disorder caused by argon plasma processing is recovered by heat treatment in vacuum while oxygen vacancies are compensated by the final ozone treatment. The results reveal the individual roles of sequential treatments of YBa2Cu3O
y
thin films which improve the electrical properties of ramp-edge Josephson junctions.
Newly Developed High-Speed Rotating Disk Chemical Vapor Deposition Equipment for Poly-Si Films
Authors: Terai Fujio , Kobayashi Hiroaki , Katsui Shuji , Sato Yuusuke , Nagatomo Takao , Homma Tetsuya
Published: July 2005

We have developed high-speed rotating disk chemical vapor deposition (CVD) equipment. A high deposition rate, good thickness uniformity and few particles were achieved for polycrystalline silicon (poly-Si) film deposition on a 200-mm-diameter silicon (Si) wafer, by optimizing the structure of the rotating disk CVD equipment. A magnetic bearing motor was used for rotating and controlling the 200-mm-diameter wafer at 3000 rpm, and the substrate temperature was controlled to be 600–900°C. Gas flow was also controlled to avoid the re-adsorption of reaction by-products onto the wafer surface. A deposition rate of 316 nm/min, a film thickness nonuniformity ±3%, and less than 20 particles (over 200 nm in diameter) were achieved at a deposition temperature of 680°C for poly-Si deposition on the 200-mm-diameter wafer. These results show that the number of particles can be reduced even at a high deposition rate. The mechanisms of the high performance for poly-Si deposition are considered to be the reduction in the thickness of the boundary layer of temperature above the wafer surface and the suppression of the vapor-phase reaction.
High-Field X-ray Diffraction Measurement of SmMn2Ge2
Authors: Miura Shihou , Koyama Keiichi , Okada Hironari , Shigeoka Toru , Watanabe Kazuo
Published: July 2005

The high-field X-ray diffraction measurement of a re-entrant ferromagnet SmMn2Ge2 with a tetragonal structure was carried out. The unit cell volume contracts by approximately 0.3% in the antiferromagnetic (AFM) state, compared with that of the ferromagnetic (FM) state. In the AFM state, the structural distortion recovers due to a high magnetic field, accompanied by the metamagnetic transition from the AFM state to the forced FM state.
Thickness Minimized Magnetic Circuit for Rotary-Type Voice Coil Motor
Authors: Jeong Jaehwa , Lee Jun-Hee , Yoon Hyoung-Kil , Gweon Dae-Gab
Published: July 2005

As the demand for small-form-factor disk drives for mobile devices increases, the miniaturization of voice coil motor (VCM) actuators playing important roles in track seeking and track following is an issue. In this study, we have determined that a multisegmented magnet array (MSMA) can reduce the total thickness of the magnetic circuit for a rotary-type VCM without changing the coil and air gap parameters.
Multi-Color Coherent Radiation in a Two-Dimensional Nonlinear Photonic Crystal with Rectangular Lattices
Authors: Ni Peigen , Ma Boqin , Liu Yuanhao , Cheng Bingying , Zhang Daozhong
Published: July 2005

The two-dimensional nonlinear photonic crystal: a periodically poled lithium niobate with rectangular lattice, was fabricated using field poling technique in this work. Red, yellow, green, blue, and violet coherent radiations were generated in the crystal by frequency doubling and tripling the output of a tunable optical parametric oscillator in the collinearly and non-collinearly quasi-phase-matching geometries. The results show that two-dimensional nonlinear crystal could be used to generate various colors simultaneously if the crystal was illuminated by the z-polarized fundamental beams of different wavelengths along different directions. Therefore, its application in the field of color display and integrated optics may be expected.
Effects of Fiber Cladding Diameter on Cladding-Mode Coupling in Fiber Bragg Gratings
Authors: Tran Thi Van Anh , Han Young-Geun , Lee Ju Han , Kim Sang Hyuck , Lee Sang Bae
Published: July 2005

The effects of cladding diameter on cladding-mode coupling in fiber Bragg gratings are investigated both theoretically and experimentally. The peak depth induced by the cladding-mode coupling increased with decreasing cladding diameter whilst the number of cladding-modes coupled from the core mode decreased. The wavelength spacing between the main peak and the first-order cladding-mode increased as cladding diameter decreased.
Dynamic Wavelength Allocation in Wavelength Division Multiplexing Radio-over-Fiber Access Network
Authors: Lin Wen-Piao , Peng Wei-Ren , Chi Sien
Published: July 2005

We demonstrate that dynamic wavelength add-drop multiplexing technology based on a fiber Bragg grating array (FBGA) can be used to improve the efficiency of wavelengths at a burst traffic load for wavelength division multiplexing radio-over-fiber (ROF) access networks. Moreover, we also propose an upstream injection-locked longitudinal mode scheme in a remote node to offer a simple ROF interface. Experimental results demonstrate that these technologies can provide robust and reliable characteristics for large radio terminals.
UV Rayleigh–Mie Raman Lidar for Simultaneous Measurement of Atmospheric Temperature and Relative Humidity Profiles in the Troposphere
Authors: Hua Dengxin , Kobayashi Takao
Published: July 2005

A Rayleigh–Mie Raman lidar system at a wavelength of 355 nm has been upgraded for simultaneous measurements of atmospheric temperature, relative humidity and aerosol profiles in the troposphere. Temperature is determined from the Rayleigh spectral linewidth. Water vapor is determined from the intensity of the water vapor vibration-Raman line centered at 407 nm. A high-resolution grating is used to separate the water vapor vibration-Raman line and Rayleigh–Mie scattering spectrally from the lidar returns. Two Fabry–Perot filters with a dual-pass optical layout are used to detect the temperature changes. The measurement shows that statistical temperature errors of less than 1 K are obtained up to a height of 3.5 km, and the uncertainties of the water vapor in relative humidity are less than 10% at a height of 2.5 km when using a lidar system with 200-mJ laser energy, a 25-cm-diameter telescope and 3.5-min observation time. The performance of the lidar system is evaluated by comparison with radiosonde measurements. Close agreements are obtained between the lidar and radiosonde measurements.
Determination of Band Alignment of Hafnium Silicon Oxynitride/Silicon (HfSiON/Si) Structures using Electron Spectroscopy
Authors: Kamimuta Yuuichi , Koike Masahiro , Ino Tsunehiro , Suzuki Masamichi , Koyama Masato , Tsunashima Yoshitaka , Nishiyama Akira
Published: July 2005

We investigated the band alignment of hafnium silicon oxynitride (HfSiON) on Si, using reflection electron energy loss spectroscopy (REELS) and X-ray electron spectroscopy (XPS). REELS was found to be effective for determining the bandgap energy of high-k materials. In HfSiON films, although the bandgap (E
g), energy barrier of electrons (ΔE
c) and holes (ΔE
v) decreased abruptly at high nitrogen concentration, they retained values as large as 1 eV. The bandgap narrowing can be ascribed to Hf–N formation inside HfSiON films. We speculate that HfSiON films are formed by insulating trihafnium tetranitride (Hf3N4) or its pseudo-alloy (Hf3N4)
x
(HfO2)1-x
as short-range order in the material, instead of forming conducting HfN.
Statistical Parameter Extraction for Intra- and Inter-Chip Variabilities of Metal–Oxide–Semiconductor Field-Effect Transistor Characteristics
Authors: Okada Kenichi , Onodera Hidetoshi
Published: July 2005

To design high-yield products, we must consider not only the inter-chip variability but also the intra-chip variability of transistor characteristics. In this paper, we propose a statistical parameter extraction considering both intra- and inter-chip variabilities. In the proposed method, the model parameters of intra-chip variability are directly extracted from the measured current variation, so that the accuracy of current variation is expected to improve. The extracted parameters are compared with the measured delay variation of the ring oscillator to verify the accuracy of the proposed method.
Low Temperature Sintering and Piezoelectric Properties in Pb(ZrxTi1-x)O3–Pb(Zn1/3Nb2/3)O3–Pb(Ni1/3Nb2/3)O3 Ceramics
Authors: Ahn Cheol-Woo , Song Hyun-Cheol , Park Seung-Ho , Nahm Sahn , Uchino Kenji , Priya Shashank , Lee Hyeung-Gyu , Kang Nam-Kee
Published: July 2005

High-power ceramics of the composition 0.8Pb(Zr0.5Ti0.5)O3–0.2Pb[(Zn0.8Ni0.2)1/3Nb2/3]O3 (0.8PZT–0.2PZNN) + 0.5 wt% MnO2 have excellent piezoelectric and dielectric properties such as d
33=320 pC/N, ε
33
T/ε
o=1227, k
p=0.54, and Q
m=1265. However, the sintering temperature of this composition is high, approximately 1200°C, restricting the use of cheap base metal electrodes in the fabrication of multilayer components. In this study, we provide a solution to this problem and report a low sintering temperature high-power composition in a PZT–PZNN system. CuO and Al2O3 were selected as sintering agents. It was found that the addition of CuO can reduce the sintering temperature to 920°C, but it can also significantly reduce the piezoelectric properties. The reduction of Q
m magnitude was 81% when 0.5 wt% CuO was added. The addition of Al2O3 as a sintering agent was found to improve Q
m magnitude but significant reductions in piezoelectric and dielectric properties were observed. The addition of excess ZnO and NiO was found to improve the density and piezoelectric properties, but it was also found to reduce Q
m magnitude. Consequently, the optimization of the concentration of the sintering agents was carried out, and the optimized low sintering temperature high-power composition was found to be 0.875Pb(Zr0.5Ti0.5)O3–0.125Pb[(Zn0.8Ni0.2)1.5/3Nb2/3]O3 + 0.5 wt% MnO2 + 0.2 wt% CuO + 0.3 wt% Al2O3. The piezoelectric properties of the specimens of this composition sintered at 920°C were found to be k
p=0.581, Q
m=809, d
33=345 pC/N, ε
3
T/ε
o=1345, and T
c=330°C.
Low Temperature Sintering of Ca[(Li1/3Nb2/3)1-xTix]O3-δ Based Microwave Dielectric Ceramics with Glass Frit
Authors: Ha Jong-Yoon , Choi Ji-Won , Kang Chong-Yun , Yoon Seok-Jin , Choi Doo Jin , Kim Hyun-Jai
Published: July 2005

The microstructures and the microwave dielectric properties of Ca[(Li1/3Nb2/3)1-x
Ti
x
]O3-δ (CLNT) ceramics with different amount of glass frit additions were investigated. Addition of glass frit(B2O3–ZnO–SiO2–PbO system) improved the densification and decreased the sintering temperature from 1150°C to 900°C of Ca[(Li1/3Nb2/3)1-x
Ti
x
]O3-δ microwave dielectric ceramics. The dielectric constants (ε
r) and bulk density were increased, as increasing glass contents from 10 wt% to 15 wt%. The quality factor (Q·f
0), however, was decreased slightly. The temperature coefficients of the resonant frequency (τf) shifted positive value as glass contents were increased. The dielectric properties of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3-δ with 12 wt% glass sintered at 900°C for 3 h were ε
r=40, Q·f
0=12,500, τf=-8 ppm/°C, respectively. The relationship between the microstructure and dielectric properties of ceramics was studied by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM).
Characterization of Si- and Mo-codoped Bi3.35La0.75Ti3O12 Ferroelectric Thin Films
Authors: Ohki Hiroshi , Fujisaki Yoshihisa , Ishiwara Hiroshi
Published: July 2005

Si- and Mo-codoped Bi3.35La0.75Ti3O12 (BLT) films were formed on Pt/Ti/SiO2/Si(100) structures by a sol–gel spin-coating method. It was found that the saturation properties of polarization vs. voltage (P–V) hysteresis loops are improved by optimizing the concentration ratio between Mo and Si atoms in the codoped BLT (BLTM–Si) films. The remanent polarization (2P
r) in the BLTM–Si (Mo=0.5%, Si=0.25%) film was 35.9 µC/cm2, which was much larger than those in a Mo-doped BLT film (32.0 µC/cm2) and a BLT film (26.0 µC/cm2). It was also found that the higher Si concentration was favorable for enhancing breakdown voltages in the BLTM–Si films. It was speculated from X-ray photo-electron spectroscopy (XPS) observation that improvements of the ferroelectric and insulating properties were due to substitution of Ti4+ site with Mo6+ and formation of SiO2, respectively.
Microstructures and Dielectric Properties of Low Temperature Cofired BiNbO4–ZnNb2O6 Ceramics with Ag-Electrode
Authors: Lee Hong Ryul , Lee Byoung Duk , Yoon Ki Hyun
Published: July 2005

0.9BiNbO4–0.1ZnNb2O6 ceramics with the sintering agent, CuO–V2O5, were sintered at low firing temperatures of 850–900 °C. The degradation of dielectric loss in the cofiring process with the Ag electrode has been studied with the change of the sintering conditions. It was found that the degradation occurred primarily due to the formation of pores and second phases. After Ag-electrode application and subsequent cofiring, silver was detected at the interface of BiNbO4–ZnNb2O6/electrode. X-ray diffraction analysis of the BiNbO4–ZnNb2O6 ceramics cofired with Ag-electrode showed a second phase formation. This reaction revealed an interaction between the silver and the niobium. The microwave dielectric properties of the 0.9BiNbO4–0.1ZnNb2O6 ceramics cofired with Ag electrode with increasing sintering time were associated with an increase in porosity and second phase formation including Ag and Nb ions.
Epitaxial Growth Map for Bi4Ti3O12 Films: a Determining Factor for Crystal Orientation
Authors: Watanabe Takayuki , Funakubo Hiroshi
Published: July 2005

Bi4Ti3O12 films were epitaxially grown at 600–750°C on various types of single-crystal oxide substrate by metal-organic chemical vapor deposition. In terms of the oxygen interatomic distances of the substrates used, the crystal orientations of the deposited epitaxial films were classified into three groups: (118), in-plane c-axis, and (001) orientations. The films on substrates with an oblong in-plane oxygen unit, had a (100)/(010) and/or (118) orientation, wheras those on substrates with a square in-plane oxygen unit had (001) or (h
k0)/(k
h0) orientation. There was an intermediate region between the (100)/(010) and (118) orientations at the present deposition temperature, where both orientations coexisted. As a result, the relationship between in-plane oxygen interatomic distances of the substrates and film orientation was summarized into an epitaxial growth map. This map is applicable to the epitaxial growth of other bismuth-layer-structured ferroelectric thin films.
Methods to Obtain High-Contrast-Ratio Twisted Nematic Liquid Crystal Device at Wavelength of 1.55 µm
Authors: Wang Bin , Zhang Yanli , Wang Xinghua , Bos Philip J.
Published: July 2005

A very high contrast ratio 90° twisted nematic (TN) liquid crystal device at a wavelength of 1.55 µm is a very useful optical component in fiber optical interconnections, but it is not easy to obtain. In this paper the reasons for some difficulties in achieving a high contrast ratio are explained and a practical way to fabricate a high contrast ratio TN cell is provided. Using this method we fabricated many TN cells at a wavelength of 1.55 µm and achieved a contrast ratio higher than 40 dB.
A Low-Voltage 4.6 GHz Injection Locked Frequency Divider in Standard 1.8 V 0.18 µm Complementary-Metal–Oxide–Silicon Technology
Authors: Yeh Mei-Ling , Liou Wan-Rone , Chen Chung-Hsing , Tsai Chun-An
Published: July 2005

A fully integrated 1.5 V, 4.6 GHz injection-locked frequency divider is designed and implemented for low-voltage 5 GHz wireless local area network front-end circuit applications. An LC tank load is used in the oscillator design to decrease power consumption. The measurement results show a resonant frequency range from 4.4 to 4.6 GHz for the control voltage V
c varying from 0 to 1.5 V. The chip has an additional capacitor to provide steady power and to decrease the power noise injected into the output resonant signal. This injection locked frequency divider is implemented using the TSMC 0.18 µm single-poly-six-metal 1.8 V silicide process. The entire chip area is 2.1×1.2 mm2.
Liquid Crystal Alignment Effects and Electro Optical Performances of Twisted Nematic-Liquid Crystal Display Using Ion-Beam Alignment Method on Nitrogen-doped Diamond Like Carbon Thin Film Layer
Authors: Park Chang-Joon , Hwang Jeoung-Yeon , Kang Hyung-Ku , Seo Dae-Shik , Ahn Han-Jin , Kim Jong-Bok , Kim Kyung-Chan , Baik Hong-Koo
Published: July 2005

Nitrogen-doped diamond-like carbon (NDLC) thin films exhibit a high electrical resistivity that is similar to the properties shown by diamond-like carbon (DLC) thin films. The diamond-like transport property in NDLC thin films comes from a material consisting of sp2-bonded carbon versus the sp3-bonded carbon of DLC. In addition, NDLC thin films have a better thermal stability than the DLC thin films, because C:N bonding in the NDLC thin films is stronger against thermal stress than C:H bonding in the DLC thin films. The liquid crystal (LC) alignment effects of ion beam irradiation on the NDLC thin films and the electro optical (EO) performances of the ion-beam-aligned twisted nematic (TN)-liquid crystal display (LCD) with oblique ion beam exposure on an NDLC thin film surface were studied. A good uniform nematic liquid crystal (NLC) alignment with ion beam exposure on the NDLC thin films was observed. In addition, good EO properties, a residual DC property and particularly the good thermal stability of the ion-beam-aligned TN-LCD on NDLC thin films was achieved.
Low-Temperature Heteroepitaxial Growth of SiC on (100) Si Using Hot-Mesh Chemical Vapor Deposition
Authors: Yasui Kanji , Eto Jyunpei , Narita Yuzuru , Takata Masasuke , Akahane Tadashi
Published: July 2005

The crystal growth of 3C-SiC films on (100) Si substrates by the hot-mesh chemical vapor deposition (HMCVD) method using monomethylsilane (MMS) as a source gas was investigated. A mesh structure of hot tungsten (W) wire was used as a catalyzer. At substrate temperatures above 750°C and at a mesh temperature of 1600°C, 3C-SiC crystal was epitaxially grown on Si substrates. From the X-ray rocking curve spectra of the (311) peak, SiC was also epitaxially grown in the substrate plane. From the dependence of growth rate on substrate temperature and W-mesh temperature, the growth mechanism of SiC films by HMCVD was considered.
Protein Crystallization by Combining Laser Irradiation and Solution-Stirring Techniques
Authors: Adachi Hiroaki , Niino Ai , Murakami Satoshi , Takano Kazufumi , Matsumura Hiroyoshi , Kinoshita Takayoshi , Warizaya Masaichi , Inoue Tsuyoshi , Mori Yusuke , Sasaki Takatomo
Published: July 2005

Bovine adenosine deaminase in the absence of an inhibitor (free-ADA) does not form crystals when using conventional crystallization methods. Using a solution-stirring technique, we recently succeeded in generating a small number of free-ADA crystals. In this paper, we demonstrate the combination of laser-irradiated growth and stirring (COLAS). This technique was found to be useful for controlling crystal nucleation and growth, which led to the production of a much larger number of high-quality free-ADA crystals.