bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and properties of tantalum oxide films by sol‐gel method
Authors: Ōishi Tomoji , Nakazawa Tetsuo , Katou Akira 
Published: July 2007

AbstractThe preparation of tantalum oxide thin film by the sol‐gel method is discussed. The conditions of the film growth are investigated carefully to avoid pinholes and cracks. In particular, the effect of hydrochloric acid added to the sol solution is clarified.The spectral and electrical properties of the thin film are investigated. The as‐grown film was amorphous and became crystallized at 720°C. The relative dielectric constant increases with an increase of the heat‐treatment temperature and the breakdown voltage decreased rapidly when the heat‐treatment temperature exceeded 600°. The optimum heat‐treatment temperature to achieve both high relative dielectric constant and high breakdown voltage was 400°C.It was found by TEM observation that the rapid degradation of the breakdown voltage was due to pinholes created during crystallization process.
Low‐temperature formation of gate‐sio2 films for poly‐si tfts by o2‐ar sputtering
Authors: Suyama Shiro , Okamoto Akio , Shirai Seiiti , Serikawa Tadashi 
Published: July 2007

AbstractHigh‐quality gate‐oxide films for poly‐Si TFTs are obtained successfully by oxygen‐argon sputter deposition at low temperature (200°C). SiO2 films deposited in an oxygen‐argon mixture on poly‐Si have higher resistivities and breakdown fields than those deposited only in argon and thermal oxides grown on poly‐Si, resulting in the same film characteristics as thermal oxides grown on single‐Si. Moreover, poly‐Si TFT mobilities are improved considerably by mixing oxygen, resulting in very high mobility of 383 cm2/V · s. This high mobility is caused by reduction in SiO2/Si interface states and in barrier heights at the poly‐Si grain boundaries in addition to the improvement of poly‐Si films.These characteristic improvements result from migration enhancement of sputtering particles on film surface and the reduction of plasma damage by oxygen mixture. These results confirm the usefulness of gate‐oxide films sputter‐deposited in an oxygen‐argon mixture for low‐temperature fabrication of high‐quality poly‐Si TFTs.
Characterization of interfaces of sio2and thin gaas active layers for gaas ics
Authors: Miyazaki Masaru , Imamura Yoshinori , Oda Hiroto , Saitoh Tadashi 
Published: July 2007

AbstractTo improve the controllability of threshold voltage of FETs for high‐performance GaAs ICs, it is necessary to establish a processing method of fabricating a surface‐protective SiO2layer without changing the thin active‐layer thickness.In this paper, a new method is proposed for evaluating the thickness of a removed GaAs active layer. This technique involves sheet resistance measurement of FET devices after surface treatment. Using this method, about a 5‐nm thick GaAs layer was found to be removed by the HF etching process for an SiO2film deposited by thermal CVD. This phenomenon is due to the formation of an intermediate layer between SiO2and GaAs interfaces. This intermediate layer consists of GaAs oxides and excess As.Spectroscopic ellipsometry has been applied to evaluate the thickness of the intermediate layer. Using this method, it was found that no intermediate layer is formed in the case of SiO2films fabricated by photo‐CVD, which is advantageous for low‐temperature processing. Furthermore, no removal of the GaAs active layer was found after HF etching of the SiO2films. SiO2films made by the photo‐CVD method are most suitable as protective layers for thin GaAs active layers of GaAs ICs.
Light coupling characteristics of a planar microlens
Authors: Oikawa Masahiro , Imanishi Hideki , Kishimoto Takashi 
Published: July 2007

AbstractThe two‐dimensional (2‐D) integrated planar microlens (PML) is expected to be used in connection with various 2‐D devices in parallel optical fiber communication systems. In this paper, we demonstrate recent progresses made for PML and its light coupling characteristics. The coupling characteristics between (1) LD and single‐mode fiber, (2) LED and GI‐50 fiber, (3) single‐mode fiber and single‐mode fiber, and (4) single‐mode fiber and detector were evaluated. In this paper, we evaluate coupling characteristics corresponding to single lens in an array.
Use of a modified mode‐matching method to analyze microstrip lines with thick strip conductors
Authors: Nakai Takashi , Tsuji Mikio , Shigesawa Hiroshi 
Published: July 2007

AbstractThis paper proposes an analytical method for microstrip lines with finite metallization thickness of the strip. The reliability of solution for such lines depends greatly on the treatment of the behavior of electromagnetic fields near the conductor edges of the strip. For example, when the conventional mode‐matching method is used for the analysis, considerable modal functions are required to represent the field behavior near the conductor edge, making it difficult to obtain accurate results.An alternative method is presented for microstrip lines with finite metallization thickness of the strip. This method is based on the mode‐matching method already presented by the authors where singularities of the electromagnetic field at the conductor edges are taken into account. The effectiveness of the present method is verified by investigating the convergence of solution and the edge effect in detail and also by comparing the results with others reported in the literature.
Advanced analyses for reduction of contamination in ulsi manufacturing line
Authors: Mizogami Yasuo , Ajioka Tsuneo 
Published: July 2007

AbstractAnalytical methods applied for clean ULSI manufacturing lines are discussed. Traced metals of such transition metals as Fe and light elements such as Al and Na, which influence device performance, can be detected with high sensitivity and reproducibility through a combination of both total reflection X‐ray fluorescence (TRXRF) and polysilicon encapsulation secondary ion mass spectroscopy (PC‐SIMS) methods. High‐resolution analytical electron microscopy (AEM), together with Auger electron spectroscopy (AES) and electron probe microanalysis (EPMA), is powerful for analyzing a nanoscale microscopic region (where a diffusion and re‐excitation of secondary electrons cannot be neglected). A method of chemical analysis for ULSI manufacturing process line is proposed, that is, TRXRF with TRXRF + HF condensation and PC‐SIMS for traced metallic contamination and wafer EPMA with AES and AEM for particles and device defects. The metallic contamination in almost all processes has been evaluated, and it was found that those analytical techniques are very effective and useful.
Observation of magnetic domains of magnetic recording medium
Authors: Sakurai Tomoaki , Shimada Yutaka , Sueyoshi Toshinobu , Okuwaki Toyoji 
Published: July 2007

AbstractUsing the colloid‐SEM technique for observing minute magnetic domains, combined with the gas evaporation method where high resolution was needed, an attempt was made to observe the magnetization profile through a magnetically recorded S‐VHS tape in order to analyze the recording magnetization pattern produced by the application of an external magnetic field.From this, simultaneously with the first observation of the magnetization pattern of a dual wavelength superimposed recording, it was found that, with the short wavelength of the recorded magnetization, the observed magnetization decreases and, moreover, it became clear that, with respect to the short wavelength region, it is of the same magnitude as the recorded wavelength.
The effects of post‐hydrogenation on amorphous‐silicon thin‐film transistors
Authors: Ahn Byung‐Chul , Usami Koh‐Ichi , Kanoh Hiroshi , Sugiura Osamu , Matsumura Masakiyo 
Published: July 2007

AbstractThe characteristics of amorphous silicon thin‐film transistors fabricated by chemical vapor deposition method is discussed in detail in conjunction with posthydrogenation. As the hydrogenation around an active interface starts, the transistor performance is abruptly improved and then does not change with further hydrogenation. A critical condition for hydrogenation for such an abrupt improvement may be accounted for based on a simple formula using a transit time of hydrogen atoms. A desirable thickness of amorphous silicon films for high performance TFT is thicker than 100 nm. In addition, it is recommended that hydrogenation is to be made at a temperature as low as possible as long as it can be possible.
Dynamic characteristics of leakage current in amorphous silicon thin‐film transistors
Authors: Motai Tomonobu , Suzuki Kouhei , Suzuki Kouji 
Published: July 2007

AbstractThe transient off‐currents of thin‐film transistors (TFTs) have been characterized. The authors connected the TFT to a capacitor equivalent to an actual pixel capacitance and made accurate measurements of the voltage at the capacitor under a drive condition actually used for the TFT‐LCDs. The currents were calculated from the measured voltages. Inverted staggered‐type TFTs were used with the gate on‐voltageVgs= 20 V and the drain voltageVsig=Vsigc± 5 V (Vsigc= 4 ± 10 V). It has been found that the off‐current shows an increase or decrease with a time delay of a few milliseconds. The change in the off‐current has been characterized as a relation between the gate bias voltageVgsand the off‐currentIds. Comparing the results with the dc characteristics, it has been found that theIdsvs.Vgscurves approach the dc curves from the positive side ofVgs'i.e., the transient current curves shift from their dc curves in the positive direction ofVgs. The authors have verified that this behavior of the off‐current with time delay can be explained by introducing a trap level inside the TFT.
High‐performance polycrystalline silicon tfts using self‐aligned grain boundary control technique
Authors: Shinohara Toshiro , Tarui Yasuo 
Published: July 2007

AbstractTo improve the reproducibility of the properties of thin‐film transistors (TFTs) formed by using solid‐phase grown polycrystalline silicon, a self‐aligned grain boundary control technique was developed. In this technique, the gate electrode of a coplanar TFT serves as a mark for ion implantation to the source and drain regions. At the same time, it limits amorphization of polycrystalline silicon only to the channel region. The channel region becomes amorphized by a high‐energy silicon ion beam through the gate electrode and oxide. However, since the silicon ions penetrate through the source and drain regions, crystalline seeds remain in the regions. Then the solid‐phase growth is carried out in the regions from the source and drain regions to the center of the channel before the crystalline nuclei are formed in the channel region.By this process, the presence of the grain boundary is limited to the center of the channel. When this technique is used, the mobility is improved by 60 percent and the scattering of the mobility value is reduced to half.
Application and study of the wiener‐hopf technique from filtering viewpoint
Authors: Uchida Kazunori , Noda Takeaki , Matsunaga Toshiaki 
Published: July 2007

AbstractThis paper introduces a filtering operation in the spectral domain which extracts the spectrum corresponding to semiinfinite or finite range in the original space. Its application to electromagnetic problems also is considered.First, it is demonstrated that for a semiinfinite boundary value problem, the rigorous Wiener‐Hopf solution can be obtained in terms of algebraic filtering operations.Second, it is shown that for finite boundary value problems, the rigorous solutions cannot, in general, be obtained only through algebraic filtering operations. Three approximate methods also are proposed for the latter problems: a direct numerical method; an approximation based on the formal solutions; and an iterative method. As an application of the iterative method, the electromagnetic wave scattering by a conducting strip is considered and an analytic expression is derived for surface currents which holds in the high‐frequency region. Numerical examples also are given for the surface current distributions.
History and Trend of Giant Microelectronics
Authors: Morozumi Shinji 
Published: July 2007

AbstractGiant microelectronics is defined as technology which forms electronic devices with fine structures on a large‐area substrate such as a glass. They are applied to image input/output (I/O) devices of active‐matrix liquid‐crystal displays, printer heads, and image sensors. The thin‐film transistor (TFT) is the typical device formed on such a large‐area substrate. It has been developed since the 1960s, realized for practical applications in the 1980s, and will be used widely in the 1990s.For active‐matrix liquid‐crystal displays, amorphous Si TFTs which are formed at low temperature by plasma CVD have been used. Recently, these displays have begun to be used for personal computers. However, the cost reduction of these displays must be achieved by increasing the size of the substrate and throughput of the products. At the same time, the integration of the driver circuits using the low‐temperature polycrystalline Si TFT must be carried out.Japan is a leader in the production of giant electronics devices. However, to establish this technology, international cooperation will be important.
Layered structure devices with a‐Axis‐Oriented YBa2Cu3O7 ‐ x films
Authors: Fujimaki Akira , Terai Hirotaka , Hayakawa Hisao 
Published: July 2007

AbstractTo clarify the characteristic of contact between a‐axis‐oriented YBa2Cu3O7 ‐ x (YBCO) and normal conduction material, two types of SNS junctions were formed. In the YBCO/Au/Nb junction, the Josephson coupling was confirmed from the magnetic field characteristic. In addition, the London penetration depth in a‐axis‐oriented YBCO was calculated to be around 800 nm. It was found that this large penetration depth causes an increase in kinetic inductance, resulting in the influence on the current flow distribution in the junction.The current density and IcRn product were estimated to be two orders of magnitude larger than those in the c‐axis‐oriented junction (1.0 × 109 A/cm2 and 100 μ V, respectively) and anisotropic electrical conduction in YBCO was confirmed. It was found also that the order parameter of YBCO attenuated drastically at the YBCO/Au interface. In the PrBa2Cu3O7 ‐ x (PBCO)/Au/Nb junction, a Josephson junction with a good junction planar uniformity was formed when PBCO was less than 20‐nm thick.The coherence length of PBCO was estimated to be 4 nm from the PBCO thickness dependence of the IcRn product. Even when the PBCO film was as thick as 300 nm, the abnormal decrease of the junction resistance due to the superconductivity of YBCO was observed. The mechanism of the forementioned symptoms must be clarified in the future.
Fabrication and properties of high Tc superconductor tunnel junctions using organic film as a barrier
Authors: Okabe Hiroshi , Moriya Masataka , Usami Koichi , Kobayashi Tadayuki , Goto Toshinari 
Published: July 2007

AbstractUsing hexamethyldisilane (HMDS), high Tc super‐conductor/HMDS/metal superconductor junctions were fabricated. First, a YBa2Cu3O7 ‐ x YBCO film was made by dc hollow cathode sputtering or rf off‐axis sputtering. Then HMDS was absorbed in the film. In this case, one molecular layer (about 1 nm) was formed; Pb (Tc = 7.2 K) was deposited as a counterelectrode. Measurements of current‐voltage characteristics were made for this tunnel junction thus obtained. As a result, an energy gap and Josephson current were observed. Also, a microwave response and a magnetic field dependence of Josephson current were investigated.
A superconducting‐base transistor using Ba1‐xKx BiO3 Superconductor
Authors: Usuki Tatsuro , Suzuki Seiji , Iyori Masahiro , Yamano Kouji , Suzuki Hiroshi , Yamamoto Tetsuya , Yoshisato Yorinobu 
Published: July 2007

AbstractAn analysis of the performance of a superconducting‐base transistor using Ba1‐xKxBiO3 (BKBO) has been made. Also, an Au/natural barrier/BKBO/SrTiO3 (Nb‐doped) superconducting‐base transistor has been fabricated and its performance has been examined.The analysis of a quasi‐particle transmission in an interface of base/collector or superconductor/semiconductor, which is the most important factor for its device characteristics, has been carried out. When the interface barrier is of Schottky type, the transmission probability depends significantly on the barrier height (U0). If U0 · Δ (superconducting energy gap), a transmission of more than 0.9 can be obtained even for low‐energy quasiparticles of about 3Δ.It was confirmed experimentally that about 2 percent of low‐energy quasi‐particles can reach a collector and they are injected through a tunnel junction (common‐base current gain α = 0.02). Experimental results of common‐base characteristics are well founded based on the assumption that a barrier height of a BKBO/SrTiO3 (Nb‐doped) is U0 = 280 me V and that a collector is a superconductor degenerated at about 30 me V.
Design of a low‐power universal literal circuit
Authors: Tsuhako Shin‐Ichiro , Afuso Chushin , Zukeran Chotei 
Published: July 2007

AbstractIn the universal literal circuit (ULC) previously proposed, since the two threshold values of the literal circuit are variable by external control signals, four‐valued logic circuits have attracted considerable attention. However, to realize LSI, there was room for improvement from the viewpoint of power consumption.In this paper, as a literal, with the other characteristics remaining the same, a new low‐power ULC circuit with power consumption decreased by 1/285 is proposed. Also, the threshold voltage variation due to the body‐effect of MOS transistors, having a critical influence on the level discrimination characteristics of the circuit, is solved by introducing body‐effect compensating transistors. Moreover, by SPICE simulation, it is verified that the low‐power ULC works satisfactorily.
Electro‐optic effect of phase‐transition liquid crystals separated by polymer network
Authors: Fujikake Hideo , Takizawa Kuniharu , Kikuchi Hiroshi 
Published: July 2007

AbstractA new light‐scattering liquid crystal device of chiral nematic liquid crystal dispersed in three‐dimensional polymer network is proposed. The liquid‐crystal device has been fabricated, and its fundamental electrooptic properties have been examined. Each cholesteric domain of focal conic texture, whose helical axis orients randomly but is fixed by a polymer wall, exhibits phase transition to nematic phase by an applied voltage. Therefore, the device has a high‐speed response (less than 500 μ ms) and high contrast ratio (100 : 1). Also, the device can perform as a stable gray‐scale memory because of its multidomain structure. It has an advantage of self‐supported structure, ease of fabrication of a large‐size device, and no requirement of sealing gap; thus, it is applicable for a full‐color projection display and a high‐speed, large‐area light shutter.
Evaluation of surface structure of cadmium arachidate langmuir‐blodgett films with atomic force microscope
Authors: Shibata Miki , Kataoka Akio , Okada Hiroyuki , Onnagawa Hiroyoshi , Miyashita Kazuo 
Published: July 2007

AbstractIn this paper, an atomic force microscope (AFM) observation is attempted for the surface structure of the cadmium arachidate Langmuir‐Blodgett (LB) film. The measurement region is on the order of micrometers and the vertical resolution is on the order of nanometers for the deposited film surface of one to five layers. Different surface structures were observed in the LB films with the hydrophobic tail at the surface and those with the hydrophilic head at the surface. The LB films with the hydrophobic tail at the surface are stable. The molecular area derived from the molecular image of the AFM was identical to 0.2 nm2 estimated from the μ‐A curve even if the deposition ratio is 0.7 to 0.8. There was no correlation between the surface orientation direction and the dipping direction.The LB film with the hydrophilic head at the surface has an unstable layered structure. Although the surface structure immediately after deposition is a flat layer of monomolecular films, it changes easily to a step structure associated with the bilayer structure of cadmium arachidate. This structure is considered to be caused by local peeling off of the film molecules deposited on the substrate and deposition to the surface with the hydrophilic head. The structural change observed by the AFM was in good agreement with the one due to the overturning model proposed by Honig.
Optical odor sensors using potential‐sensitive dye coatings
Authors: Yamakawa Shinzo 
Published: July 2007

AbstractThere have been many reports on odor recognition sensors based on multichannel semiconductor gas sensors but few on odor recognition using an optical fiber sensor.Using a fiber‐optic sensor array with potential‐sensitive dye coatings, this paper investigates a sensing system to recognize odor by an optical spectral pattern. The edges of a fiber were coated with films consisting of potential‐sensitive dyes and silicone resin to form a transmission‐type fiber‐optic sensor. When these sensors are exposed to organic vapor odorants, the absorption spectra of the dyes changed, depending on the differences of odorants, indicating that this type of sensor array can be used as an odor‐recognition sensor.Selecting six dyes from 16 dyes, a six‐channel optical fiber sensor array was fabricated. The changes of absorption spectra of dyes were measured and data were processed by a computer. Response patterns to organic vapors were measured and it was confirmed that pattern recognition could be achieved.
GaAs‐pin/ferroelectric liquid crystal spatial light modulator (GaAs‐pin/FLC‐SLM) and its applications
Authors: Hashimoto Masashi , Kitayama Ken‐Ichi , Ishibashi Shigeki , Fukuda Yukio 
Published: July 2007

AbstractA spatial light modulator GaAs‐pin/ferroelectric liquid crystal spatial light modulator (GaAs‐pin/FLC‐SLM) was developed in which a GaAs photodiode is used as a photodetector, and a ferroelectric liquid crystal is used as a modulator. In the present device, write‐in with visible light and a transmission‐type readout at infrared are possible. Other characteristics of this device include a high‐speed operation due to the use of a ferroelectric liquid‐crystal and no need for erasing light due to the use of a pin diode.In this paper, the configuration of the SLM is presented and the operating principle is explained by means of an operation model. Next, experimental examples as a switching device are described. Also, several examples of the system applications are presented.The first example is a self‐routing crossbar switch. In this switch, the 1.3‐μm signal light is switched by providing a header at a different wavelength to a connected output port. the present SLM is used as an optical switch section. the experimental results of the present switch with 2 × 2 ports are reported.The second example of the system application is an optical parallel processor which is based on the accumulative threshold characteristic of the present SLM. By means of this characteristic, logic operation is possible for time series parallel optical signals. It is presented that the sequential operation system can be constructed in a much simpler configuration. the experimental results for configuration of the principle are added.