bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of Mechanical Stress Simulator for Surface-Mount Devices
Authors: Keiji Yamamoto Keiji Yamamoto 
Published: October 2002

A mechanical stress simulator for surface-mount devices was developed, which employed the finite-element method. The moisture distribution stage can calculate the moisture distribution of the LSI package exposed to temperature and humidity conditions. The heat conduction stage determines the time-dependent temperature distribution of the package immersed in a solder bath. Using the moisture and temperature distributions thus calculated, the mechanical stress stage gives the mechanical stress distribution in the package. Two groups of samples were prepared for solder dipping experiments. In one group, after dry baking for initialization, samples absorbed moisture by exposure at 30°C 85% (absorption process). In the other group, samples were exposed at 85°C 85% for 168 h and then dry-baked at 70°C (desorption process). These two groups have different moisture distributions in their packages. The results of solder dipping experiments are analyzed from the calculated mechanical stress values. In the absorption process, calculated maximum von Mises equivalent stress over the sectional molding compound σ; max increases monotonically with absorption time. Then, σ; max approaches its saturated value as absorption time tends to infinity. In the desorption process, σ; max decreases with desorption time and approaches the thermal stress value when desorption time tends to infinity. These calculations explain the effect of moisture distribution on package cracking.
Ultrasonic Velocity Measurement Using Optical Beam Deflection
Authors: Tatsuro Matsuoka Tatsuro Matsuoka , Akihiro Kumata Akihiro Kumata , Shinobu Koda Shinobu Koda , Hiroyasu Nomura Hiroyasu Nomura 
Published: October 2002

A newly designed apparatus for measurement of ultrasonic velocity in liquids based on the optical beam deflection technique is constructed. This method relies on the phase-sensitive detection of the optical deflection angle. The apparatus is suitable for measurements in the frequnecy range from 5 MHz to 75 MHz. In this study, application of this apparatus to water and diisobutylphthalate is described.
Three-Dimensional Dynamic Imaging by Spherical Pulsed Wave of Ultrasound
Authors: Tojo Hirofumi , Oshiro Osamu , Matani Ayumu , Chihara Kunihiro , Asao Masato , Furukawa Toshiyuki 
Published: October 2002

We developed an ultrasonic dynamic imaging system to obtain a three-dimensional echogram in a blood vessel. The method makes it possible to detect the echo signal from objects instantaneously without scanning an ultrasonic beam using a ring array probe. First, we examined the spatial resolution. Second, we performed experiments using a butter block and a copper plate. The results show that this system has a spatial resolution below 1.0 mm, and also that a butter block in a plastic tube and a moving copper plate can be detected by this system.
Photoluminescence of ZnS 1-xSex:Te Prepared by Solution Growth Using Sb-Chalcogenides as Solvent
Authors: Hiroyuki Araki Hiroyuki Araki , Hisashi Kanie Hisashi Kanie , Masatoshi Sano Masatoshi Sano 
Published: October 2002

Photoluminescences due to Te isoelectronic traps were investigated for Te-doped ZnS1-x
Se
x
crystals (0 ≤x ≤1) grown from Sb-chalcogenide solutions. The optical depths of the isolated Te atom center and the nearest-neighbor Te–Te pair center were determined from the emission spectra and the excitation spectra at 77 K. These depths decreased monotonically with increasing Se composition x. The theoretical relation between the optical depth and the composition x on the basis of the Koster-Slater one-band one-site approximation was best fitted to the experimental data by assuming the values of the matrix element of the impurity potential J
ZnS:Te = 2.41 eV, J
ZnSe:Te = 1.27 eV, and the effective width of the valence band T
ZnS = 6.02 eV, T
ZnSe = 6.21 eV. According to the criteria in the theory, excitons bound to the isolated Te atoms exist in ZnS1-x
Se
x
:Te for 0 ≤x < 0.85 and excitons bound to the Te–Te pairs exist throughout the entire composition range. The emission band observed at 2.61 eV in ZnSe:Te was shown to be due to the excitons bound to the Te–Te pairs.
Macrostructure of Melt-Crystallized Vinylidene Fluoride /Trifluoroethylene Copolymers (37/63, 65/35, 73/27 mol%)
Authors: Sunao Sasaki Sunao Sasaki , Akira Funato Akira Funato , Kohji Kubo Kohji Kubo , Akio Chiba Akio Chiba 
Published: October 2002

Macrostructures of melt-crystallized vinylidene fluoride/trifluoroethylene (37/63), (65/35) and (73/27) mol% copolymers have been studied using a scanning electron microscope (SEM) and small-angle X-ray scattering (SAXS). The SEM images show stacks of lamellar crystals with thicknesses of about 1000 Å. However, experimental SAXS intensities do not show diffraction peaks that are sufficiently distinct to suggest the presence of the lamellar stacks; rather, they decrease almost monotonically as the scattering angle increases. Two structural models are introduced to calculate theoretical SAXS intensity, and the degree of agreement between theoretical and experimental SAXS intensities is examined for each model. The first model is the finite lamellar stack model, which presents a good approximation of the macrostructures shown in the SEM images. However, this model yields poor agreement in higher angular regions, which indicates that the lamellar stack model is not valid for analyzing the experimental SAXS intensities of melt-crystallized copolymers. Thus, a second model is proposed: crystalline blocks cohere and constitute quasi lamellae, which are then stacked. The theoretical SAXS intensity based on the second model gives a satisfactory description of the experimental SAXS intensity.
Formation of Silicon and Cobalt Silicide Nanoparticles in CaF 2
Authors: Masahiro Watanabe Masahiro Watanabe , Fumitaka Iizuka Fumitaka Iizuka , Masahiro Asada Masahiro Asada 
Published: October 2002

We have demonstrated a method of forming silicon and cobalt silicide nanoparticles (<10 nm) in CaF2 grown on a Si(111) substrate using codeposition of Si, Co and CaF2. It is shown that the size and density of silicon and silicide particles can be controlled by the substrate temperature and the evaporation rate of CaF2 and Si. At a growth temperature of around 200°C and a flux ratio of Co:Si:CaF2 of about 1:2:2, an average diameter of 7 nm was obtained.
Nano-Optical Studies of Individual Nanostructures
Authors: Lars Samuelson Lars Samuelson , Niclas Carlsson Niclas Carlsson , Pedro Castrillo Pedro Castrillo , Anders Gustafsson Anders Gustafsson , Dan Hessman Dan Hessman , Joakim Lindahl Joakim Lindahl , Lars Montelius Lars Montelius , Anders Petersson Anders Petersson , Mats-Erik Pistol Mats-Erik Pistol , Werner Seifert Werner Seifert 
Published: October 2002

Optical techniques play a significant role in studies of nano-structures. The electronic structures of quantum dots, for example, vary with the geometric sizes in an ensemble, resulting in broadened spectral lines. Recently, different forms of local spectroscopic techniques have been applied to investigate such inhomogeneously broadened emission lines. In this paper we report on three methods for local spectroscopy: cathodo-luminescence, luminescence induced by a scanning tunnel microscope and microphotoluminescence. Each of these techniques is shown to have the capacity to investigate single quantum dots, with linewidths in the range 40–1000 µeV. Besides demonstrating the possibility of imaging and spectroscopically studing individual dots, we also demonstrate the possibility of investigating single impurity atoms, in imaging as well as in emission spectroscopy modes.
Evaluation of Hot Electron Coherent Length Using Well Width Dependence of the Resonance Characteristics of Resonant Tunneling Diodes
Authors: Young Cheul Kang Young Cheul Kang , Michihiko Suhara Michihiko Suhara , Kazuhito Furuya Kazuhito Furuya , Ryuya Koizumi Ryuya Koizumi 
Published: October 2002

In order to evaluate the hot electron coherent length from the resonance characteristics of resonant tunneling diodes (RTDs), the dependence of the resonant level width on various broadening mechanisms is investigated. From the dependence of the resonant level width on the well width, it is shown that the individual contributions to resonant level broadening (phase relaxation and well width variation) can be analyzed separately. The resonant level widths were measured experimentally and compared with theoretical results, and the coherent length was evaluated to range from 80 to 120 nm at 4.2 K in GaInAs at hot electron energies of 50 to 100 meV.
Nanoscale Lithography with Electron Exposure of SiO 2 Resists
Authors: Thomas K. Whidden Thomas K. Whidden , John Allgair John Allgair , Angela Jenkins-Gray Angela Jenkins-Gray , Maroun Khoury Maroun Khoury , Michael N. Kozicki Michael N. Kozicki , David K. Ferry David K. Ferry 
Published: October 2002

We report on electron-beam patterned hydrocarbon residues on silicon dioxide as chemical initiators in high temperature HF vapor etching for the production of nanolithographic masks (∼20 nm feature size). These are of utility in reactive ion etching based pattern transfer to the underlying substrate and, potentially, as dielectric components in nanoscale devices. Metallic cobalt, deposited through the oxide mask, has been used to generate 12–20 nm wide lines of cobalt silicide.
Difference of Si Selective Growth on Al 2O 3 and SiO 2 Substrates by Electron Beam Irradiation Method
Authors: Makoto Ishida Makoto Ishida , Hirosi Tayanaka Hirosi Tayanaka , Shunichi Yanagiya Shunichi Yanagiya , Tetsuro Nakamura Tetsuro Nakamura 
Published: October 2002

Based on a proposed growth model of Si selective epitaxy on Al2O3, the selective epitaxy of Si on both Al2O3 and SiO2/Si substrates was investigated. It is clarified that the incubation time for the Si growth on Al2O3 depends on electron dose density and growth conditions. The incubation time increased with increasing electron dose density from 1015 to 1018 electrons/cm2. Thickness of the selectively grown layer is determined by taking the product of the growth rate and the incubation time difference. Selective Si deposition on SiO2/Si substrates was studied using an electron-beam irradiation method, because SiO2 is also the oxide material as Al2O3, and the same phenomena could be expected from our proposed mechanism. It was confirmed that the selective growth of Si was possible on the SiO2/Si substrate modified by electron beam irradiation. However, Si deposition on SiO2 occurred on the irradiated area, in contrast to the case of Si on Al2O3.
Low-Energy Focused Ion Beam Doping during Molecular Beam Epitaxial Growth for the Fabrication of Three-Dimensional Devices: The Effect of Dopant Surface Segregation
Authors: James H. Thompson James H. Thompson , Pier J. Sazio Pier J. Sazio , Harvey E.Beere Harvey E.Beere , Geraint A. C. Jones Geraint A. C. Jones , David A. Ritchie David A. Ritchie , Edmund H. Linfield Edmund H. Linfield , Gilbert W. Smith Gilbert W. Smith , Michael Houlton Michael Houlton , Colin R. Whitehouse Colin R. Whitehouse 
Published: October 2002

An extreme example of surface segregation is found in Sn-doped GaAs grown by molecular beam epitaxy (MBE). Abrupt changes in the doping profile are not possible, instead the dopant concentration decreases exponentially towards the wafer surface from the point at which doping was terminated. In this work it is shown that segregation can be suppressed by implanting the Sn from a very-low-energy (50 to 300 eV) ion beam during growth. The effect of ion implantation energy is studied using secondary ion mass spectroscopy (SIMS) to measure the depth profile of the implanted Sn. It is found that the level of incorporation can be increased by up to a factor of eight using a 300 eV ion energy.
Platinum as Recombination-Generation Centers in Silicon
Authors: Bei Deng Bei Deng , Hiroshi Kuwano Hiroshi Kuwano 
Published: October 2002

The general equations of steady-state lifetime in semiconductors with multiple deep impurity levels are derived based on the recombination theory. From the obtained equations the six capture cross sections of three Pt-induced levels in silicon are experimentally determined. The behaviors of minority carrier lifetime and leakage current in Pt-diffused devices are also discussed. It is found that the minority carrier lifetime is influenced by the three Pt-related levels and that the major contribution to the leakage current arises from the level ofEc-0.52 eV.
Preparation of Rutile TiO2Films by RF Magnetron Sputtering
Authors: Kunio Okimura Kunio Okimura , Akira Shibata Akira Shibata , Naohiro Maeda Naohiro Maeda , Kunihide Tachibana Kunihide Tachibana , Youichiro Noguchi Youichiro Noguchi , Kouzou Tsuchida Kouzou Tsuchida 
Published: October 2002

TiO2films were prepared by rf (13.56 MHz) magnetron sputtering using a mixture of Ar and O2gases. At a total pressure of 2 mTorr, 100% rutile TiO2films were successfully obtained on non heated substrates with rf power of 200 W, while 100% anatase TiO2films were deposited at a pressure of 20 mTorr. Spatial profiles of both emission of excited species and plasma parameters were measured by optical emission spectroscopy (OES) and the Langmuir probe method. At a pressure of 2 mTorr, it was found that high-energy electrons are generated at a certain radial position near the cathode surface where the transverse magnetic field is maximum, and the strong localization of plasma was observed. It was proven that the energetic species impinging on the growing film are responsible for the formation of the rutile phase even if the substrate is at room temperature.
Metal (CoSi 2)/Insulator (CaF 2) Hot Electron Transistor Fabricated by Electron-Beam Lithography on a Si Substrate
Authors: Wataru Saitoh Wataru Saitoh , Takashi Suemasu Takashi Suemasu , Yoshifumi Kohno Yoshifumi Kohno , Masahiro Watanabe Masahiro Watanabe , Masahiro Asada Masahiro Asada 
Published: October 2002

We fabricated a small-area metal (CoSi2)/insulator (CaF2) hot electron transistor using electron-beam lithography. The transistor is composed of a CoSi2/CaF2 (1.9 nm)/CoSi2 (1.9 nm) tunnel emitter and a CaF2 (5 nm) collector barrier on an n-Si(111) substrate. The emitter mesa area is 0.9 × 0.9 µm2. Although the measured characteristics show, for the first time, clear transistor action with a curve similar to those of semiconductor HETs, the collector current increases without saturation due to leakage current through the SiO2 film under the external electrode pads. The intrinsic device characteristics (zero leakage current) exhibited saturation, and a current gain β ≥ 36 was obtained at 77 K.
Electron-Energy-Loss Spectroscopy of Oxide Superconductor Bi2Sr 2CaCu 2O 8
Authors: Terauchi Masami , Tanaka Michiyoshi , Takahashi Takashi , Katayama-Yoshida Hiroshi , Mochiku Takashi , Kadowaki Kazuo 
Published: October 2002

Transmission electron-energy-loss spectra of the oxide superconductor Bi2Sr2CaCu2O8 have been taken from perfect crystalline areas (100 nmφ) in an energy range of 0–60 eV at temperatures of 30 K, 100 K and 300 K. A peak at about 0.6 eV was observed at these temperatures instead of a peak at about 1 eV which was reported to be a free-carrier plasmon peak. The dielectric function derived from the loss-function indicates that the peak at about 0.6 eV can be attributed not to a collective excitation (plasmon) but to an interband transition. The electron density which contributes to the peak has been calculated to be 2 ×1019 electron/cm3. The peaks and shoulders of the spectra (the loss-function) are assigned to individual interband transitions. The temperature dependence of ε
2 has been found around 2.5 eV and 5.5 eV.
CFX (X=1-3) Radical Measurements in ECR Etching Plasma Employing C4F8 Gas by Infrared Diode Laser Absorption Spectroscopy
Authors: Miyata Koji , Takahashi Kunimasa , Kishimoto Shigeru , Hori Masaru , Toshio Goto Toshio Goto 
Published: October 2002

CF, CF2 and CF3 radical densities were investigated in electron cyclotron resonance (ECR) plasma employing C4F8 (octafluoro-cyclobutane) and C4F8/H2 gases using infrared diode laser absorption spectroscopy.
It was found that CF2 radical density in ECR C4F8 plasma was on the order of 1013 cm-3 at microwave power below 300 W and pressure of 0.4 Pa, which was quite high compared to CF and CF3 radical densities. With addition of H2 to C4F8 plasma, CF radical density increased markedly and the CF radical became dominant along with the CF2 radical. The mechanisms of these behaviors of radicals are discussed on the basis of these experimental results.
Temperature Dependence of Power Reflectivity of the First-Wall Materials in the Synchrotron Radiation Range
Authors: Noriharu Takada Noriharu Takada , Masaaki Nagatsu Masaaki Nagatsu , Michiya Shimada Michiya Shimada 
Published: October 2002

The temperature dependence of power reflectivity in the synchrotron radiation range was measured for candidate first-wall materials of the fusion reactor, such as B4C-coated isotropic graphite, C/C composite material, silicon carbide (SiC), tungsten (W), molybdenum (Mo) and SUS-316. The measurements were carried out using a vacuum vessel with a pressure of about 3 mTorr to avoid oxidation. Distinct temperature dependence of reflectivity was observed only for B4C-coated isotropic graphite. For the other materials, power reflectivities were insensitive to temperature in the range from 300 K to ∼900 K. Theoretical analysis of the results is also presented.
Magnetically Excited Plasma Oxidation of InP
Authors: Akihiro Funyu Akihiro Funyu , Shingo Sato Shingo Sato , Hideaki Ikoma Hideaki Ikoma 
Published: October 2002

High-quality oxide of InP having an excellent interface with InP was successfully grown with magnetically excited plasma oxidation of InP and annealing at 260°C for 15 min in \morO ambient. Outstanding capacitance-voltage (C-V) characteristics were obtained, which clearly showed both inversion and accumulation behaviors. The C-V curves at 300 K and 80 K coincided well with each other, indicating the absence of frequency dispersion. X-ray photoelectron spectroscopic measurements showed that InPO4, the perfect oxide of InP, was the dominant component species in the oxide with a small amount of In2O3.
New Fabrication Technology for Integrating Field Effect Transistors and Diodes
Authors: Jung Jong-Wan , Song-Cheol Hong Song-Cheol Hong , Young-Se Kwon Young-Se Kwon 
Published: October 2002

We demonstrated a new integration technology for field effect transistors (FETs) and diodes. This technology uses selective-area metalorganic chemical vapor deposition (MOCVD) for FET and diode layers. FETs (called FECFET) fabricated by this technology have very short distances between the drain and source, so that the characteristics such as knee voltage and transconductance are superior to those of conventional FETs with the same gate length. Because this structure has an n+-doped contact layer under an n-doped active layer, it is easy to integrate with a high-quality diode having low series resistance. By this approach, diodes with low series resistance and low junction capacitance have been fabricated. To demonstrate the integration of the diode and FECFET, a 36 GHz single balanced diode mixer and an intermediate frequency (IF) amplifier have been fabricated on a GaAs wafer.
Near-infrared Intersubband Transitions in InGaAs/AlAs Quantum Wells on GaAs Substrate
Authors: Takashi Asano Takashi Asano , Susumu Noda Susumu Noda , Tomoki Abe Tomoki Abe , Akio Sasaki Akio Sasaki 
Published: October 2002

We report intersubband transitions in InGaAs/AlAs quantum wells on GaAs substrate. The intersubband-transition wavelength and absorption coefficient are investigated as functions of sample structure and growth conditions. It is shown that a decrease in well width leads to a shorter transition wavelength but a reduction in the absorption coefficient. The reduction in the absorption coefficient can be recovered by increasing the In composition of the well and by suppressing the segregation of In during growth. With these optimizations, a very short intersubband-transition wavelength of 1.9 µm is achieved.
Characterization of Czochralski Silicon Wafers Grown at a Low Growth Rate by Photoluminescence Spectroscopy
Authors: Mototsugu Hamada Mototsugu Hamada , Takashi Katoda Takashi Katoda 
Published: October 2002

Microdefects in silicon wafers were characterized based on photoluminescence measurements obtained with a high sensitivity Fourier-transform (FT)-Raman spectrometer. Some luminescence peaks were obtained from a crystal which was pulled at a low growth rate while they were not observed from a crystal which was pulled at a normal rate. The luminescence peaks were observed in the region of the wafers where ring-oxidation-induced-stacking-faults (ring-OSF) were formed and inside the ring. By comparing the behavior of annealing-induced defects, that is D-line and P-line defects, and the grown-in defects observed in low-growth-rate crystals, it was concluded that the grown-in defects were P-line defects. Based on the PL intensity of the peak at 0.75 eV which was observed from a crystal pulled at a low growth rate, it was found that the effect of the thermal history of a crystal pulled at 0.8 mm/min was equivalent to an annealing at 500°C for 3 h.
Effects of Sol–Gel Processing Variables on the Texture Growth of LiNbO3 Thin Film
Authors: Won Dong Hoon , Hur Nam Hwi , Kwangsoo No Kwangsoo No 
Published: October 2002

Highly oriented lithium niobate ( LiNbO3) thin films were fabricated using the sol–gel spin coating method. The effects of the sol–gel processing variables, such as reflux time, crystallization temperature and substrate, on the development of texture on the thin film were investigated. The film made from the solution refluxed for 5 h and deposited on a sapphire (012) substrate showed highly oriented growth at the crystallization temperature of 500° C. The film had homogeneous and pore-free microstructure. The film made from the solution refluxed for 1 h showed only preferred orientation and porous microstructure under the same processing conditions. The thin films deposited on MgO(100) substrates were polycrystalline. The crystallization temperature and the film thickness significantly affected the crystallinity and the orientation of the films.
Characteristics of Bleustein-Gulyaev-Shimizu Wave Resonators on Ceramics at High Frequencies
Authors: Kazuhiko Morozumi Kazuhiko Morozumi , Michio Kadota Michio Kadota , Seigo Hayashi Seigo Hayashi 
Published: October 2002

At frequencies above 60 MHz , tuning-free surface acoustic wave (SAW) resonators with many reflectors using Rayleigh SAW are generally used. However, Rayleigh SAW resonators for use in the 60–150 MHz range have some disadvantages such as cost. We have already developed a BGS wave resonator, which is being used commercially in the 30–60 MHz range. When we improved the characteristics of BGS wave resonators by using small-particle , poreless ceramic substrates developed for high-frequency BGS waves, we obtained good resonance characteristics up to 160 MHz. We also obtained good characteristics when we tested the resonator in a DECT demodulator circuit.
10 GHz Surface Acoustic Wave Filters with Narrow-Gap Interdigital Transducer Structure
Authors: Kazuhiko Yamanouchi Kazuhiko Yamanouchi , Kazuo Aoki Kazuo Aoki , Takatoshi Tsuji Takatoshi Tsuji , Yasuo Wagatsuma Yasuo Wagatsuma 
Published: October 2002

Controllable well-insulated gaps between electrodes can be obtained by anodic oxidation of the edges of the regions of an Al film covered by photo resist. This technique is used to fabricate surface acoustic wave narrow gap interdigital transducers (NG-IDTs) and narrow gap floating electrode type unidirectional transducers (NG-FEUDTs). Experimental results indicate that the SAW NG-IDTs and NG-FEUDTs operate in the 10GHz range and have an electrode width of less than 0.2 µm.