bluuebunny/crossref_metadata_2025 huggingface dataset:
Adhesion of Photoresist Pattern Baked at 80 to 325°C in Tetramethyl-ammonium-hydroxide Aqueous Solution
Authors: Kawai Akira , Takata Hitoshi Nagata
Published: February 2005

Adhesion characteristics of a photoresist thin film baked onto a spin-on SiO2 layer at 80 to 325°C are studied in a tetramethyl-ammonium-hydroxide (TMAH) developer. The maximum value of adhesion strength is observed in the temperature range of 150 to 250°C. It is found that the surface energy model cannot explain all of the experimental results. The following two models are introduced as new adhesion factors: (i) decrease of surface energy of the TMAH developer due to dissolution of a photoresist into it above 250°C and (ii) decrease of mechanical strength of a photoresist pattern by swelling under 150°C.
Influence of Al Surface Modification on Selectivity in Via-Hole Etching Employing CHF3 Plasma
Authors: Ohiwa Tokuhisa , Arikado Tsunetoshi , Horioka Keiji , Hasegawa Isahiro , Matsushita Takaya , Kouji Shimomura Kouji Shimomura , Haruo Okano Haruo Okano
Published: February 2005

The Al etching characteristics in CHF3 plasma have been studied. The etching rate increased drastically with decreasing pressure. Analysis of the surface exposed to CHF3 plasma revealed that the Al surface was not covered with a fluorocarbon film, but was fluorinated. It has become evident that Al fluoride is sputtered much faster than Al. That is, fluorination of the surface results in the high etching rate of Al in a CHF3 plasma. Furthermore, the surface analyses of Si, Al, W and Ni exposed to CHF3 plasma made it clear that fluorocarbon films are formed on the materials whose etching products have high vapor pressure, and are not formed on the materials whose vapor pressure for the etching products is very low. The continuous fluorine consumption which is caused by evaporation of etching products through the fluorocarbon film, leads to formation of fluorocarbon film.
Formation of High-Density Etch Pits on a Si Surface after Low-Temperature Heating in an Ultrahigh Vacuum
Authors: Nakamura Nobuo , Takashi Ohshima Takashi Ohshima , Kiyokazu Nakagawa Kiyokazu Nakagawa
Published: February 2005

The effects of heat treatment in an ultrahigh vacuum on (111)Si crystallinity are investigated using Si substrates and molecular beam epitaxy films. On the heated substrates, a high density of etch pits is observed following Secco etching. The etch pit densities of specimens heated at 600°C, 700°C and over 800°C for 100 min are 6×107 cm-2, 1.4×108 cm-2 and 3-5×10-9 cm-2, respectively. However, if over 5 nm of the surface is removed by etching, no etch pits are formed. These defects affect the crystal quality of epitaxial layers. Films grown below 700°C on a substrate preheated to 850°C have defects in all regions. On the other hand, films grown above 700°C only have defects within 8 nm of the surface.
Transport Properties in Hexagonal Arrays of Antidots with Different Carrier Densities
Authors: Takahara Junichi , Gamo Kenji , Namba Susumu , Takaoka Sadao , Murase Kazuo
Published: February 2005

Magnetotransport measurement has been performed in two-dimensional electron gas with a hexagonal array of antidots. Several magnetoresistance peaks are observed and are analyzed with an extended Drude model. The calculation is in good agreement with experimental results. The carrier concentration is varied by gradual illumination and the dependence of magnetoresistance on carrier concentration is measured and discussed.
Control of Epitaxial Relation of GaAs Film on Fluoride/Si(111) Structure
Authors: Ono Atsuki , Kazuo Tsutsui Kazuo Tsutsui , Seijiro Furukawa Seijiro Furukawa
Published: February 2005

The X-ray diffraction measurements have revealed that the type B region, whose crystallographic orientation is rotated 180° about the surface normal with respect to the CaF2 film (rotational twin), partially exists in a GaAs film on CaF2(111). It is found that the fraction of the type B region increases as the GaAs growth temperature increases for good crystallinity in GaAs films. A decrease in temperature at the initial stage of growth followed by an increase in temperature, i.e., the two-step growth method, is found to be very effective for suppressing the generation of the rotational twins at the GaAs/CaF2 interface so as to grow high-quality GaAs on CaF2/Si(111).
Dependence of Offset Error on Overlay Mark Structures in Overlay Measurement
Authors: Kawai Akira , Watanabe Jinzou , Takata Hitoshi Nagata
Published: February 2005

Measurement precision, especially the offset error in the automatic measurement technique of overlay, was studied for sub-half-micron device manufacturing. Experimental data showed that the offset error depended on the cross-sectional structure rather than the reflectivity or the roughness of the measurement marks. Dependence of the offset error upon equipment factors, e.g., the incident angle of illumination, was also studied. The depth of focus was considerably increased up to 1.5 µm on the LSI wafers with well-aligned light. This paper also shows an offset error on critical levels in sub-half-micron device manufacturing.
Experimental Study of the Spectral Characteristics of a High Power, Pulsed D2O Laser for Application to Plasma Diagnostics
Authors: Nagatsu Masaaki , Tsubouchi Yuichi , Takada Noriharu , Sasaki Koichi , Tsukishima Takashige , Okada Tatsuo , Okajima Shigeki , Sato Kohnosuke , Sudo Shigeru , Tsunawaki Yoshiaki
Published: February 2005

Spectral characteristics of a high power, pulsed optically pumped far infrared D2O laser developed for the ion Thomson scattering on the Heliotron E have been studied using a high frequency resolution heterodyne detection system with a 1.35 GHz sampling digitizer. The temporal behavior of D2O laser emission spectra have been measured for various D2O gas pressures and different pumping intensities. Results apparently reveal the multiple line spectral structures which consist of several longitudinal modes with a mode spacing of about 36 MHz and a linewidth of less than 5 MHz. These results suggest the capability of utilizing the present D2O laser in the ion Thomson scattering experiment, provided the incident wave spectrum is measured simultaneously with the scattered wave spectrum.
Nondestructive Depth Profiling Using Soft X-Ray Emission Spectroscopy by Incident Angle Variation Method
Authors: Yamauchi Shoichi , Hirai Masaaki , Kusaka Masahiko , Iwami Motohiro , Nakamura Hatsuo , Minomura Shigeru , Watabe Hirokuni , Kawai Masao , Soezima Hiroyoshi
Published: February 2005

We constructed a sample reclining stage for soft X-ray emission spectroscopy (SXES), where we intended to carry out nondestructive depth profiling using an incident angle variation (IAV) method. The penetration depth of an incident electron decreases with a reclining sample stage. One of the characteristics of the IAV method is that the incident electron beam energy is constant; thus, it is easy to obtain information related to a quantitative analysis of the integrated intensity of soft X-ray emission spectra. This method has been applied for a specimen with NiSi2/Si(111) structure. We have analyzed the change in shape of the Si L2,3 emission band spectrum in a region of the Si substrate to the NiSi2 layer, and have shown that we can determine the distribution of the Si element from the integrated intensity of Si L2,3 emission spectra.
Deposition of Low Hydrogen Content Silicon Nitride Film Using High-Intensity Vacuum Ultraviolet Light Source in Windowless Photochemical Vapor Deposition Reactor
Authors: Ueno Tomo , Nagayoshi Hiroshi , Morinaka Haruji , Koichi Kuroiwa Koichi Kuroiwa , Yasuo Tarui Yasuo Tarui
Published: February 2005

Silicon nitride (SiN) films were deposited using a windowless photochemical vapor deposition reactor, a unified reactor with a lamp, at a substrate temperature of 200°C. For vacuum ultraviolet (VUV) light emission, H2/He mixture gas was introduced into the light source part of the reactor where 2.45 GHz microwaves were introduced through a discharge cavity. High intensity VUV light with the wavelength of 121.6 nm, which is due to Rydberg transition of electrons in H atoms from 22P to 12S, was irradiated into the deposition part of the reactor in order to dissociate source gases such as NH3 and SiH4 into higher order radicals of NH and SiH. Characterization of the deposited SiN film by means of Fourier transform infrared spectroscopy (FT-IR), electron spectroscopy for chemical analysis (ESCA), etc., reveals that low hydrogen content has been achieved in the SiN film with high density, high breakdown field, and high resistivity even at the low deposition temperature of 200°C.
Formation and Properties of Ferroelectric Bi4Ti3O12 Films by the Sol-Gel Process
Authors: Tohge Noboru , Yoshifumi Fukuda Yoshifumi Fukuda , Tsutomu Minami Tsutomu Minami
Published: February 2005

Ferroelectric Bi4Ti3O12 films have been prepared through the sol-gel process from corresponding metal alkoxides, which were chemically modified. The homogeneous films of the Bi4Ti3O12 single phase were obtained on Pt substrates by the heat-treatment at 500°C, under optimum conditions of process parameters such as concentration and aging time of a starting solution.
Single-Event Upset Test of Static Random Access Memory Using Single-Ion Microprobe
Authors: Matsukawa Takashi , Noritake Katsunori , Koh Meishoku , Hara Ken-ichi , Makoto Goto Makoto Goto , Iwao Ohdomari Iwao Ohdomari
Published: February 2005

A novel method for testing single-event immunity in VLSIs has been developed using a single-ion microprobe which is composed of an ion microprobe and a single-ion extractor. Testing of single-event upset has been performed in various sites of a 64 kbit static random access memory (SRAM) by hitting a micron-size device area with a single ion. Results of error address mapping agreed well with the hit sites. Through the experiment, no permanent radiation damage was introduced, which indicates the suitability of the current method for testing single-event immunity.
Maintenance Voltage Enhancement by Bias Fields in Repetitively Pulsed Discharges
Authors: Suzuki Mutsumi , Curzon Shigeo Mikoshiba
Published: February 2005

In various discharge devices, such as dc gas discharge displays, repetitive pulse discharges are maintained by pulses of amplitude V
pm. Static voltages are also frequently applied to electrodes in the discharge cells to produce bias fields which are intended to reduce the magnitude of V
pm. In this paper, it is shown that bias fields which are too weak to ignite inter-electrode discharges, nevertheless increase the magnitude of V
pm, and that this increase gets larger as the discharge cells are aged. The enhancement in V
pm is larger as the pulse widths are reduced. A suggested explanation of the effect is that transient currents driven by the bias fields create wall charges. The wall charges then create electric fields which oppose the effects of the applied voltage pulses, thereby increasing the magnitude of V
pm.
SiO2 Tapered Etching Employing Magnetron Discharge of Fluorocarbon Gas
Authors: Ohiwa Tokuhisa , Horioka Keiji , Arikado Tsunetoshi , Hasegawa Isahiro , Haruo Okano Haruo Okano
Published: February 2005

SiO2 tapered etching has been studied with special emphasis on the substrate temperature. A tapered etching profile was formed accompanying a polymer deposition on the side wall, and a high etching rate was obtained by lowering the substrate temperature. The polymer film deposited on the side wall was easily removed together with photoresist by O2 plasma ashing to yield a very smooth side wall in the via hole without any residual films. Experiments on polymer deposition revealed that the polymerization at as low a temperature as -70°C gives a fluorine-rich polymer film with poor durability in a plasma environment, and the etchants for SiO2 are released by ion bombardments at the interface between the polymer and the underlying SiO2 to enhance SiO2 etching.
Electron Energy Distribution Function in Neon-Nitrogen Mixture Positive Column
Authors: Takashi Kimura Takashi Kimura , Kazuyuki Ohe Kazuyuki Ohe
Published: February 2005

The electron energy distribution function (EEDF) is measured in a Ne-N2 mixture positive column, whose mixing ratio x (=Ne/Ne+N2) is varied from 0 to 1, keeping the gas pressure and the discharge current constant at 0.52 Torr and 40 mA, respectively. The EEDF drastically shifts to the N2-dominated one by mixing in a small amount of N2.
Adjoint Spectrum I: an Algorithm to Extract Target Spectra Under Spectral Interferences for Use in On-Line Spectrometry
Authors: Bouzidi Moncef , Kagawa Naoki , Osami Wada Osami Wada , Ryuji Koga Ryuji Koga
Published: February 2005

A spectrum measured with a sensitive device inevitably suffers from interference spectra which are both predictable and unpredictable. Amplitude of a target gas spectrum can be obtained as a result of the inner product of the measured spectrum and an “adjoint spectrum” generated by the algorithm proposed here. The result is independent of amplitudes of interference spectra as far as its profiles are known beforehand. The effectiveness is extended to unknown interferences if their profiles are gently sloping. Another important feature is that this algorithm can be executed in real-time on a microprocessor. Such features are favorable for field measurements of concentrations of atmospheric gases in real-time and in situ. If too many interference spectra are involved, the system becomes vulnerable to random noise included in the measured data. A compromise can be sought, but the solution depends on the intensity of the noise. A tunable diode laser absorption spectrometer (TDLAS) adopting this technique and designed to be used in field measurements of atmospheric methane, has shown an accuracy of 6 ppb in a laboratory test, which is more than one order better than the case without this algorithm.
X-Ray Mask Fabrication Process Using Cr Mask and ITO Stopper in the Dry Etching of W Absorber
Authors: Fujino Takeshi , Sasaki Kei , Marumoto Kenji , Yabe Hideki , Nobuyuki Yoshioka Nobuyuki Yoshioka , Yaichiro Watakabe Yaichiro Watakabe
Published: February 2005

An X-ray mask fabrication technology using a tungsten (W) absorber with a chromium (Cr) mask and indium titanium oxide (ITO) stopper was developed. When SF6 was used as the dry etching gas, substantial side etching occurred because the F radical reacts with W on the sidewall. In order to prevent side etching, a SF6 and CHF3 gas mixture was applied; however, the ratio of dry etching rate of W to that of resist is low. Furthermore, the underlying layer such as that of silicon dioxide (SiO2), which was used as the etching stopper, was easily damaged. Instead of a resist mask and SiO2 stopper, a Cr layer as the etching mask and ITO layer as the stopper layer were applied. By the use of these structures and etching procedures, high aspect ratio W patterns with vertical sidewalls have been successfully fabricated.
Analog Position Analyzer for Position-Sensitive Microchannel Plate Detector by Using an IC Divider
Authors: Kusakabe Toshio , Masaya Ohmiya Masaya Ohmiya , Kozo Wada Kozo Wada
Published: February 2005

Analog position analyzers for a position-sensitive microchannel plate detector (MCP-PSD) have been simply constructed by use of fast operational amplifiers and an IC divider such as AD534K or AD734B. The analog division circuit with the AD734B shows extremely fast response to input pulses and has a wide dynamic range from 30 mV to 10 V. This circuit is found to be applicable to atomic collision experiments.
Derivation and Simulation of Higher Numerical Aperture Scalar Aerial Images
Authors: Cole Daniel C. , Barouch Eytan , Hollerbach Uwe , Orszag Steven A.
Published: February 2005

The application of scalar diffraction theory to a projection optics system is examined here for somewhat higher numerical aperture conditions upon removing the paraxial, or small angle, approximation that is typically made. A detailed derivation is given that notes the key physical assumptions originally contained in work by others on vector imaging theory. The asymptotic limit of large lenses and focal length sizes to object and image sizes is explicitly carried out, while keeping numerical apertures and magnification fixed. Numerical results of the resulting equations are presented for a variety of imaging conditions, including phase shift masks and modified illumination.
Effect of Coherence Factor σ and Shifter Arrangement for the Levenson-Type Phase-Shifting Mask
Authors: Hashimoto Kohji , Kawano Kenji , Inoue Soichi , Nakase Shinichi Itoh
Published: February 2005

To apply the Levenson-type phase-shifting mask to actual ULSI devices, we have investigated the resolution limit and the depth of focus (DOF) for several shifter arrangements experimentally. Resist patterns were printed using a KrF excimer laser stepper of 0.42 NA. It was suggested that the σ value should be decreased for the various shifter arrangements to obtain higher resolution. Moreover, it was found that resolution capabilities of irregular shifter patterns were higher than those of conventional mask patterns under the condition σ=0.3. In addition, it was found that arrangements where the optical phases for both side apertures are equal should be avoided in the fabrication of 0.30 µm rule devices by a KrF excimer laser exposure with the Levenson-type phase-shifting mask.
Simulation of X-Ray Mask Distortion
Authors: Oda Masatoshi , Ohki Shigehisa , Ozawa Akira , Takashi Ohkubo Takashi Ohkubo , Hideo Yoshihara Hideo Yoshihara
Published: February 2005

X-ray mask distortion caused by membrane and absorber stresses is investigated by computer simulation using differential equations derived from thermal stress theory. A frame supporting the membrane is stretched toward its center by the membrane tension, and the amount of displacement increases with membrane size and depends on the uniformity of the stress. Distortion is also caused by frame bowing resulting from the membrane and the absorber stresses. These distortions can be reduced by using a thick frame. Stress variation in the membrane causes in-plane distortion of the membrane. To suppress the maximum displacement to less than 0.02 µm, this stress uniformity must be less than 1%. Out-of-plane distortion of the membrane caused by the absorber stress is very sensitive to pattern size.
Simulation of Chemical Amplification Resists
Authors: Hiroshi Yoshino Hiroshi Yoshino , Hiroshi Matsumoto Hiroshi Matsumoto
Published: February 2005

A simulation model for chemical amplification resists is proposed. This model includes a bulk acid loss reaction and an acid diffusion, as well as a crosslinking reaction. Good agreement with experimental patterns was achieved only when these reactions were calculated self-consistently. The calculation revealed that, for designing chemical amplification resists, one of the key factors is the crosslinking reaction sensitivity to post-exposure bake (PEB) temperature. However, in quarter-micron pattern formation, the acid diffusion was found to significantly affect pattern profile as well as the crosslinking reaction dose.
In Situ Growth of Bi-Sr-Ca-Cu-O Films by ac Sputtering in Pure Oxygen
Authors: Yang Hong-Chang , Horng Ming-Chu Kim
Published: February 2005

We have carried out the in situ growth of Bi-Sr-Ca-Cu-O films in pure O2 using an ac sputtering technique. The films were grown at different O2 pressures. We have obtained superconducting Bi-Sr-Ca-Cu-O(2212) films which show T
c (50% resistive)=84 K and a zero resistance at 74 K. The formation and superconductivity of the films prepared in pure O2 were compared with that prepared in a mixture of Ar and O2.
Investigation of Random and Channeling Ar+Implantation-Induced Damage in Al(In)GaAs/GaAs Quantum Wells
Authors: Kieslich Albrecht , Josef Straka Josef Straka , Alfred Forchel Alfred Forchel
Published: February 2005

Ar+ ion implantation at energies up to 170 keV in GaAs/GaAlAs and InGaAs/GaAs quantum wells is used in order to study the profile of the implantation induced damage as a function of the implantation parameters like the ion energy, the ion dose and the angle of incidence. The photoluminescence (PL) emission intensity of single quantum wells (SQW) at different positions in the layer structure is used as a local probe for the study of the damage. The influence of ion channeling on the damage is investigated by varying the angle of incidence of the ion beam systematically through the major crystallographic axes of the sample. In the experiment we observe even for random implantation an unexpectically wide extension of the defect profiles, which can be described by a characteristic decay length due to a long ranging exponential tail of the damage profile. Compared to the results of random incidence ion implantation along the (100), (110), (111), and (211) axis leads to effective extensions of the damage up to a factor of about four due to ion channeling.
An Area Selective and Anisotropic Etching of Si by Synchrotron Radiation Excitation: Effects of Introducing O2 Molecules
Authors: Goto Takashi , Kitamura Osamu , Terakado Shingo , Tanaka Shigeo Suzuki
Published: February 2005

Single crystalline silicon was photochemically etched by synchrotron radiation (SR) in the presence of reactive species produced by microwave discharge. The etching gases were a mixture of SF6 and Ar. We attempted to introduce O2 gas in order to increase the area selectivity by protecting the nonirradiated area. It was found that the introduction of O2 molecules was very effective in depressing the etching of a nonirradiated area resulting in high area selectivity. Also an anisotropic feature of c-Si was obtained by addition of O2 molecules and submicron patterning was successfully performed using a stencil mask. The effect of O2 molecules was investigated by the measurement of the spectra of total electron yield and Auger electrons. It seems that the formation of an oxide layer on c-Si surface played an important role in the area-selective etching.
A Focused He+ Ion Beam with a High Angular Current Density
Authors: Hiroshima Hiroshi , Komuro Masanori , Konishi Morikazu , Tsumori Toshiro
Published: February 2005

Focusing characteristics of an ion beam from a He field ion source were investigated. For a W emitter as installed, a beam with an ion current of 0.7 pA was focused into 0.2 µm because the angular current density did not exceed 0.02 µA/sr. Improvement of angular current density was attempted by using the emission from a cleaned W (111) facet treated by field evaporation. From observation of field ion microscope images, it was found that the angular current density in the axial direction is dependent on the size of the (111) facet. For a large facet, a ringlike emission was obtained and the angular current density in the axial direction was not improved by adjustment of the extraction voltage. It is necessary to fabricate a facet of less than a few tens of atoms to achieve high current beam of axial direction. A beam with an angular current density of about 1 µA/sr was applicable to a focused ion beam after appropriate field evaporation.
Quantum Wire Fabrication by E-Beam Elithography Using High-Resolution and High-Sensitivity E-Beam Resist ZEP-520
Authors: Nishida Toshio , Notomi Masaya , Ryuzo Iga Ryuzo Iga , Toshiaki Tamamura Toshiaki Tamamura
Published: February 2005

We have evaluated the resolution of the positive electron-beam (E-beam) resist ZEP-520 using finely focused E-beam exposure for the application of quantum wire fabrication in a large area. Compared with the poly-methylmethacrylate (PMMA) resist conventionally used for nanofabrication, ZEP resist shows almost the same resolution under sensitivity improvement of one order of magnitude, and the throughput is increased by a factor of more than 100 by introducing a highly bright Zr/O/W thermal field emitter as an E-beam source. Other excellent performance characteristics, such as high dry-etching durability and process stability, allow us to apply ZEP resist for larger-area, high-density quantum wire fabrication. By both wet chemical etching and dry-etching combined with CBE selective growth, InGaAs nanostructures as small as 15 nm can be obtained with a pitch of 70 nm over several hundred µm squares.
Dynamics of Rapid Phase Transformations in Amorphous GeTe Induced by Nanosecond Laser Pulses
Authors: Nakayoshi Yoshiaki , Kanemitsu Yoshihiko , Maeda Yasuaki Masumoto
Published: February 2005

We have studied laser-induced rapid transformations of GeTe from an amorphous phase to a crystalline phase by means of nanosecond time-resolved optical reflectivity and transmission measurements. Two different processes for crystallization were observed. One of the crystallization processes is that inhomogeneous melting occurs in a laser-heated volume and large grains of crystalline GeTe are formed in the amorphous matrix. The other crystallization occurs at laser fluences well above the melting threshold. The phase transformation from the amorphous to the crystalline phases via a homogeneous liquid phase is triggered by the bulk nucleation in a highly supercooled liquid.
Recording Mechanism of Overcoated Metallized Dye Layers on Polycarbonate Substrates
Authors: Holtslag A. H. M. , E. F. McCord E. F. McCord , G. H. Werumeus Buning G. H. Werumeus Buning
Published: February 2005

The recording mechanism of a so-called CD-Recordable is reported; the disc consists of a pregrooved polycarbonate substrate, a dye, a metal reflector and an overcoat. After recording, bumps on the pregrooved substrate and pits at the dye/metal interface are observed. A method to determine the complex refractive index of a dye is explained and it will be shown how to obtain both a high reflection and a high modulation. From optical and thermal calculations and from recording experiments it is shown that two threshold temperatures are involved, associated with the softening of polycarbonate at 170°C and with a transition of the dye at 265°C.
Electroluminescence of ZnF2 Thin-Films Doped with Rare-Earth Ions
Authors: Miura Noboru , Sasaki Takashi , Hironaga Matsumoto Hironaga Matsumoto , Ryotaro Nakano Ryotaro Nakano
Published: February 2005

Electroluminescent devices based on ZnF2 thin-films have been investigated. From the ZnF2 thin-films doped with rare-earth ions (except for Sc, Y, La, Pm, Yb and Lu), electroluminescence was observed. The emission in these devices was visible from the ultraviolet to the infrared region. The color and spectral region of these electroluminescences shifted to shorter wavelength compared with those of the same ions in the ZnS-based thin-film devices for many cases. To obtain information on the excitation process for rare-earth ions, the transient behavior has also been measured.
Feasibility Study of Ge-Sb-Te Phase-Change Optical Disk Medium for One-Pass Overwrite Digital Audio Recording
Authors: Nishiuchi Kenichi , Akahira Nobuo , Eiji Ohno Eiji Ohno , Noboru Yamada Noboru Yamada
Published: February 2005

A phase-change optical disk medium utilizing a Ge12Sb39Te49 memory film showed characteristics suitable for one-pass overwriteable digital audio disk system at a low linear velocity of 1.3 m/s. Applying the multipulse recording method, the eight to fourteen modulatlon (EFM) signals were successfully overwritten using only one laser beam with a small block error rate (BLER) of <50 counts/s. The laser irradiation power was typically 13 mW for the peak power level and 7 mW for the bias level. The available cycle number was observed to be more than 104 cycles with a practical sufficient laser power tolerance of + / -20%.
Error Propagation due to Dust on a Thin-Substrate Disk
Authors: Seo Katsuhiro , Kawashima Tetsuji , Tamotsu Yamagami Tamotsu Yamagami , Tetsu Watanabe Tetsu Watanabe
Published: February 2005

An optical disk generally has a substrate with a thickness of 1.2 mm, which makes it difficult to realize a compact read-write head and double-sided magneto-optical (MO) disk drive capable of direct overwriting using magnetic field modulation. We propose a system using a disk with a thinner substrate to overcome the problems. In the new system, a very small piece of dust on the surface of the substrate can cause data errors, but error length is shorter than in the conventional system. This paper clarifies the influence of dust on the thin substrate on error propagation.
Development of Compact Disk-Write-Once Hybrid Disk
Authors: Kawanishi Toshinori , Eiji Nakagawa Eiji Nakagawa , Makoto Itonaga Makoto Itonaga
Published: February 2005

We developed the new hybrid disk which has a read-only area (ROM), that is, a premastered area, and write-once area (WO), where writing is possible. To be compatible with a compact disk (CD), the disk is a single plate and organic dye is used for the recording layer. The disk has high productivity because there is the possibility of spin-coating the organic dye onto not only the WO area but to pits in the ROM area as well. Furthermore, the disk can have multiple ROM and WO areas as the user's option.
To satisfy the CD standards a high reflection rate is achieved by means of characterizing the shape of pits in the ROM area and pregrooves in the WO area. The disk yields good CD playback signals after recording.
Designing of Photochemical Hole Burning Materials: Burning Process in Hydrogen Bonding and Proton Transfer Molecular System
Authors: Toshiro Tani Toshiro Tani , Youichi Sakakibara Youichi Sakakibara
Published: February 2005

The burning process of persistent spectral holes in quinizarin and its hydroxy derivatives is investigated from the viewpoint of hydrogen bonding and proton transfer molecular systems. Correlations among molecular structure, electronic structure and hole forming ability are substantial. A possible underlying mechanism involving diabatic crossing of the ground state is proposed and a close comparison to that in free-base porphyrin is given.
Interference-Free Determination of the Absorption Coefficient of Amorphous Silicon Thin Films
Authors: N. Maley N. Maley
Published: February 2005

Hishikawa et al. [Jpn. J. Appl. Phys. 30 (1991) 1008] recently used transmission (T) and reflection (R) measurements on amorphous silicon films to show that interference-free absorption spectra (α) can be obtained by self-consistently solving T/(1-R). We show that if R is measured with the sample illuminated from the substrate-side T and R can be converted to T
f and R
f, the transmission and reflection of a film on a semi-infinite substrate. For weakly absorbing films this simplifies the data analysis considerably as α can be obtained from T
f/(1-R
f) without any iterative procedures.
Oxygen Behavior in the Superconductor (Bi, Pb)2Sr2Ca2Cu3Oy Phase Studied by X-Ray Photoelectron Spectroscopy
Authors: Um Woo Sik , Kim Duk Hee , Kwangsoo No Kwangsoo No , Ho Gi Kim Ho Gi Kim
Published: February 2005

Samples annealed in lower and higher oxygen partial pressure than P
O2
=10-2 atm show T
c shift to the lower temperatures compared with the sample annealed in P
O2
=10-2 atm, which shows the highest T
c, 107 K. X-ray Photoelectron Spectroscopy (XPS) measurement was carried out to study the behavior of oxygen and the change of chemical environments of each ion in the high T
c phase, dependent on the annealing atmosphere changes becoming the origin of
these phenomena. The tendency toward increasing binding energies of Bi 4f7/2 and Cu 2p3/2 with increasing oxygen partial pressures during the heat treatments indicates that the mobile oxygens are located in the (Bi, Pb)-O and the Cu-O layers. We know that the valence of Cu moves to +3 with increasing oxygen content in the structure, and this increase of Cu valence indicates the enhancement of hole creation.
Perpendicular Anisotropy of Ba-Ferrite Media Studied by Ferromagnetic Resonance
Authors: Kohmoto Osamu , Jr. Chester Alexander , Kubo Osamu , Cates James C.
Published: February 2005

The anisotropy of Ba-ferrite (BaFe10.4Co0.8Ti0.8O19) particulate media having a perpendicular orientation was studied using ferromagnetic resonance. An effective anisotropy field H
k of 2.87 kOe and a gyromagnetic ratio γ/2π of 2.76 GHz/kOe were obtained. Also, the magnetocrystalline anisotropy K
u of 1.2×106 erg/cm3 was obtained for the Ba-ferrite particles.
Influence of Cooling Rate on Electrical Properties of Zinc Oxide-Based Varistors
Authors: Shr-Nan Bai Shr-Nan Bai , Tseung-Yuen Tseng Tseung-Yuen Tseng
Published: February 2005

The influence of the cooling rate on the microstructure, the nonlinear parameter α, the breakdown voltage V
1mA/cm2
, the dielectric properties and the leakage current of the ZnO varistors was investigated. The morphology of the microstructure has different appearances under the effect of the varying cooling rates. The nonlinear parameter and the breakdown voltage reached a maximum as the cooling rate was adequately chosen. In the frequency range of 600∼1 MHz, the dielectric properties of the samples dealt with at different cooling rates showed a similar tendency. However, the leakage currents of the samples showed different behavior under a constant voltage stress. As a result, the physical and electrical properties of the ZnO varistors can be said to be affected by the cooling rate.
Effect of Rapid Thermal Annealing on Electron Trapping in Thin Oxide on n-Type GaAs
Authors: Ghader Eftekhari Ghader Eftekhari
Published: February 2005

Electron trapping in the thin oxide layer of Al and Ta-n-type GaAs Metal Insulator Semiconductor (MIS) structure was studied using the flat-band voltage shift. Three trap sites for the Al contact and two for the Ta contact were obtained. The rapid thermal annealing of oxide caused changes in trap characteristics and elimination of one trap site in the Al contact.
Vicinage Effects in Secondary Electrons Yields from the (001) Surface of SnTe Induced by MeV Hydrogen Clusters
Authors: Susuki Yasufumi , Fukui Syouichi , Kenji Kimura Kenji Kimura , Michihiko Mannami Michihiko Mannami
Published: February 2005

Yields of secondary electrons from the (001) surface of SnTe are studied at the impact of 0.3-0.8 MeV/amu H+, H2+and H3+ions. The yield per ion upon impact of the Hn+ion is more thanntimes as large as that of isotachic proton impact. The observed molecular effects in the yields are explained as being the result of increased stopping power for fragment protons and of electrons released from the molecular ions upon their dissociation. It is also shown that the scaling relation, γ3=2γ2-γ1, remains roughly constant at oblique incidence angles up to 10° to the surface, where γnis the yield at Hn+incidence.
Measurement of the Bunch Length on the UVSOR Storage Ring
Authors: Lin Akihiko , Hama Hiroyuki , Takano Shiro , Isoyama Goro
Published: February 2005

We have measured the bunch length in single-bunch operation of the UVSOR (Ultraviolet Synchrotron Orbital Radiation) storage ring in a beam current region from 0.1 to 70 mA at energies ranging from 500 to 750 MeV. The momentum compaction factor of the present operation point is determined experimentally from the bunch length and the synchrotron oscillation frequency measured simultaneously at a low beam current. The bunch length increases gradually as the beam current increases, and bunch lengthening is larger when the beam energy is lower. This behavior of bunch lengthening agrees well with a prediction of the potential-well distortion theory. Based on the theory, the effective longitudinal coupling impedance is estimated as a function of bunch length.
Reactive Ion Etching Using Electron Cyclotron Resonance Hydrogen Plasma with n-Butyl Acetate Reactive Gas
Authors: Miyata Toshihiro , Minami Tadatsugu , Hirotoshi Sato Hirotoshi Sato , Shinzo Takata Shinzo Takata
Published: February 2005

Electron cyclotron resonance hydrogen plasma reactive ion etching (RIE) with n-butyl acetate reactive gas has been demonstrated. The etching mechanism is discussed for RIE of transparent conducting oxide films. The RIE technique exhibits excellent material selectivity resulting from the ability to control the etching mechanism by altering the accelerating voltage frequency. To demonstrate the practical application of RIE, an electroluminescent display fabrication is described.
Fabrication of Au Fine Patterns by Ar Sputter Etching Using MoO3 Mask
Authors: Baba Mamoru , Okamoto Masaaki , Kei Kumagai Kei Kumagai , Toshio Ikeda Toshio Ikeda
Published: February 2005

A new fabrication technique of fine Au patterns using a bilevel MoO3 film is proposed. In this process, the MoO3 film is used as an electron resist for patterning, followed by Au layer etching with Ar-ion sputtering, using the bilevel MoO3 layer as a mask. The upper layer of the bilevel MoO3 resist is suitable for use as a mask layer. The lower layer, which is sputter-deposited with lower rf power, is useful for easy removal of the MoO3 mask after sputter etching of the Au layer.
ESR of Tb3+ Ion in CuAlS2
Authors: Aksenov Igor , Yuki Kudo Yuki Kudo , Katsuaki Sato Katsuaki Sato
Published: February 2005

Electron spin resonance (ESR) of the Tb3+ ion (4f8-electronic configuration) has been studied in the crystals of wide band gap ternary semiconductor CuAlS2, grown by the chemical vapour transport technique. A Tb3+-related resonance line with g-value of about 4.0 and asymmetrical line shape has been observed and interpreted as arising from transitions within the lowest non-Kramers doublet split from the Tb3+ ion ground state by the effect of the tetragonal crystal field.
Reappraisal of Si-Interlayer-Induced Change of Band Discontinuity at GaAs-AlAs Heterointerface Taking Account of Delta-Doping
Authors: Akazawa Masamichi , Hasegawa Hideki , Hidemasa Tomozawa Hidemasa Tomozawa , Hajime Fujikura Hajime Fujikura
Published: February 2005

X-ray photoelectron spectroscopy reinvestigation is done for the recently reported Si-interlayer-induced change of the valence band discontinuity (ΔE
v) at GaAs-AlAs interfaces. The XPS measurements reproduced the large apparent change of ΔE
v caused by the Si interlayer. However, it also led to anomalous increases of separations between the core level peak and the valence band edge as well as anomalous increases of full width at half maximum of the core level spectra. It is concluded that the observed change of ΔE
v is only an apparent one. The anomalies were explained quantitatively by a new model based on the surface Fermi level pinning and interface delta-doping.
Dependence of Magnetic Field Penetration Depth on Resistivity and Critical Temperature in c-Axis-Oriented YBaCuO Thin Films
Authors: Kisu Takanobu , Iinuma Tadashi , Enpuku Keiji , Takeo Keiji Yoshida
Published: February 2005

Properties of magnetic field penetration depth λ in c-axis-oriented YBaCuO thin films were studied from inductance measurements. It was shown that the temperature dependence of λ was consistent with the local limit Bardeen-Cooper-Schrieffer (BCS) theory, and that the value of the London penetration depth was estimated to be 148 nm. Moreover, the relationship among zero-temperature penetration depth λ(0), resistivity ρ and critical temperature T
c in YBaCuO films was shown to be consistent with that obtained for conventional superconductors. By using that relationship, λ(0) could be deduced from ρ and T
c of the film.
Anisotropy in D.C. Magnetization in Textured Y0.9Ca0.1Ba2Cu4O8 Superconductors
Authors: Kumakura Hiroaki , Kitaguchi Hitoshi , Togano Kazumasa , Hasegawa Takayo , Takeshita Fumio
Published: February 2005

D.C. magnetisation curves of the textured Y0.9Ca0.1Ba2Cu4O8 (Y-124) and YBa2Cu3O7 (Y-123) were measured at various temperatures and the results were compared each other. For B⊥c-axis, no significant difference was observed in magnetization curves between these two oxides. For B//c-axis, however, Y-124 shows much larger field dependence of ΔM than Y-123 at elevated temperatures. This difference in parallel fields may be related to the twin boundary pinning and/or the two dimensionality of the oxides.
Observation of the Vortex-Glass Transition in the Tl-Based Superconducting Thin Films
Authors: Wang Chungyung , Chang Hung-Lun , Juang Jenh-Yih , Gou Yih-Shun , Uen Tzeng-Ming
Published: February 2005

The current-voltage characteristics (IVC) of Tl-based superconducting thin films as well as the magnetization of the Tl-based bulk sample were investigated. A crossover similar to the prediction of the vortex-glass to vortex-liquid phase transition in the IVC of Tl-based superconducting thin films was clearly demonstrated. More significantly, striking scaling behavior was found in the IVC which is only sample dependent and is irrelevant to the applied magnetic fields. By comparison to dc magnetization measurements on similar bulk samples, it is found that the phase boundary is not the irreversibility line commonly encountered in the flux-creep scenario.
A Magnetic Force Microscope Using an Optical Lever Sensor and Its Application to Longitudinal Recording Media
Authors: Honda Yukio , Hosaka Sumio , Kikugawa Atsushi , Tanaka Shinji , Matsuda Yoshibumi , Mikio Suzuki Mikio Suzuki , Masaaki Futamoto Masaaki Futamoto
Published: February 2005

A magnetic force microscope (MFM) is developed, which is capable of operation in both DC and AC detection modes, to allow observation of topographic and magnetic structures in the same sample area. An optical lever sensor is introduced to measure the cantilever displacement. DC detection senses the repulsive atomic force between the tip and a sample to provide surface topography information. AC detection senses the force gradient acting on an oscillating tip in the stray magnetic field emanating from the sample to provide magnetic information. A fabrication method for a sharp magnetic tips is also described. A comparison of the magnetization and surface structure images of a thin film medium observed by the MFM shows that nanometer-level roughness on the medium surface can affect the magnetic recording process.
Nonlinear Optical Properties of Carbohydrazono-Pyrazole Derivatives with Excellent Transparency
Authors: Ozaki Masanori , Daido Kazuhiro , Yoshino Katsumi , Nakagawa Mineo , Suzuki Takashi
Published: February 2005

Nonlinear optical properties and crystal characteristics of carbohydrazono-pyrazole derivatives have been studied. Many hydrazone derivatives have been synthesized and their second-harmonic generation efficiencies have been screened by means of the powder technique. Among them, it is found that 1-methyl-4-nicotinic aldehydecarbohydrazono-5-aminopyrazole (MNACAP) has a large second-order nonlinear efficiency. The MNACAP crystal belongs to the space group P21. The nonlinear coefficient of crystalline MNACAP is predicted using X-ray diffraction results and the molecular hyperpolarizability derived from the molecular orbital theoretical calculation. It is also confirmed that MNACAP has a short cut-off wavelength around 390 nm and has the high melting point of 265°C.
Photoluminescence Studies in CuAlS2 Crystals
Authors: Shirakata Sho , Aksenov Igor , Sato Katsuaki , Shigehiro Isomura Shigehiro Isomura
Published: February 2005

Photoluminescence (PL) measurements have been carried out at low temperature (77 and 10 K) on CuAlS2 crystals grown by the chemical vapor transport method. Seven sharp PL lines have been observed near the band edge. Based on the photoreflectance measurements, the PL line at 3.550 eV has been assigned to a free exciton emission. The lines at 3.540, 3.532, 3.500 and 3.475 eV are tentatively assigned to the bound excitons, and they are discussed in terms of the crystal composition and the annealing conditions. This study also refers to the PL lines and peaks at about 2.9 eV.
Effect of Surface Pretilt Angle on Optical Properties of Surface-Stabilized Ferroelectric Liquid Crystals
Authors: Itoh Nobuyuki , Kido Masami , Tagawa Akira , Koden Mitsuhiro , Shuji Miyoshi Shuji Miyoshi , Tomio Wada Tomio Wada
Published: February 2005

Surface-stabilized ferroelectric liquid crystals (SSFLC) used with high-pretilt aligning film rubbed in a parallel direction showed three states, C1U, C1T and C2, which exhibited different optical properties. The temperature dependence of the memory angles of these states was measured for eight kinds of SSFLC sample cells which were prepared using two FLC materials and four aligning films. The increase in the surface pretilt angle made the memory angle of the C1U state greater, but did not affect that of the C2 state. The experimental results were quite consistent with the calculated relationships between the memory angle and the surface pretilt angle.
Space Group Determination of Decagonal Quasicrystals of an Al70Ni15Fe15 Alloy Using Convergent-Beam Electron Diffraction
Authors: Saito Masakazu , Tanaka Michiyoshi , Tsai An Pang , Inoue Akihisa , Masumoto Tsuyoshi
Published: February 2005

Clear space group determination of a decagonal quasicrystal has been performed for the first time by convergent-beam electron diffraction (CBED) about Al70Ni15Fe15. The space group of the alloy has been revealed to be noncentrosymmetric P1̄0̄m2. The alloy is the first quasicrystal to belong to a noncentrosymmetric space group, and has been found to have a lattice period of 0.4 nm in the direction of the decagonal axis, and to accompany structural modulation waves.
Reflection High-Energy Electron Diffraction Intensity Oscillations during Si MBE Growth on HF-Treated Si(111) Surface
Authors: Kumagai Yoshinao , Fujii Kunihiro , Matsumoto Hisashi , Fumio Hasegawa Fumio Hasegawa
Published: February 2005

Reflection high-energy electron diffraction (RHEED) intensity oscillations were observed when Si was directly grown at 450°C on the Si(111) surfaces treated with pH-modified (pH=9-10) buffered HF (BHF) solution without a conventional high-temperature cleaning step in ultrahigh vacuum (UHV). On the other hand, a 5% HF-treated Si(111) surface showed weak RHEED intensity oscillations even if a 800°C, 20 min heat treatment was performed before growth in UHV. These results indicate that the Si(111) surface treated with pH-modified BHF is flat and clean enough for direct Si molecular beam epitaxy (MBE) growth on it.
Large-Area Milky Transparent Conducting Al-Doped ZnO Films Prepared by Magnetron Sputtering
Authors: Minami Tadatsugu , Sato Hirotoshi , Takata Shinzo , Ogawa Norihiro , Mouri Takashi
Published: February 2005

Large-area milky transparent conducting Al-doped ZnO (AZO) films with a wedgelike textured surface have been prepared by dc magnetron sputtering. Total transmittances of 84 and 77% and haze ratios of 10 and 53% at a wavelength of 550 nm were obtained in 1.2-µm- and 3-µm-thick milky AZO films, respectively: films were prepared at a substrate temperature of 350°C and a sputter argon gas pressure of 12 Pa. A resistivity of 5.5×10-4 Ω·cm and a sheet resistance of 1.8 Ω/sq were obtained in a large-area 3-µm-thick AZO film postannealed at 300°C for 30 min in a hydrogen atmosphere.
Atomic Image Observation of Hydrogen-Saturated Si(100) Prepared by Atomic Hydrogen Irradiation
Authors: Okada Yoshitaka , Hirofumi Shimomura Hirofumi Shimomura , Mitsuo Kawabe Mitsuo Kawabe
Published: February 2005

Atomic images of hydrogen-saturated Si(100) surface have been successfully observed by scanning tunneling microscope in ultra high vacuum. Prolonged exposures of Si(100) surface to atomic hydrogen irradiation have produced ordered hydrogen-terminated structures such as the (1×1) dihydride phase, and the (3×1) structure which was comprised of the dihydride and (2×1) monohydride phases alternately repeated. Domains of the (3×1) phase separated by anti-phase boundaries were also observed on a given (100) terrace.
Effect of Atomic Hydrogen on GaAs (001) Surface Oxide Studied by Temperature-Programmed Desorption
Authors: Yamada Masamichi , Yuichi Ide Yuichi Ide , Kiyoshi Tone Kiyoshi Tone
Published: February 2005

Atomic hydrogen (H·)-induced modification of Ga2O3-like oxide on GaAs (001) was studied by temperature-programmed desorption. H· treatment at 300°C caused a new Ga2O desorption starting at around 400°C, whereas a sample treated with molecular hydrogen gave simultaneous desorption of Ga2O and elemental As only above 500°C, the same as observed in the untreated sample. X-ray photoelectron spectroscopy showed a reduction in O1s intensity after the H· treatment. These results indicate that atomic hydrogen converts Ga2O3-like oxide into volatile Ga2O-like oxide and consequently lowers the oxide-removal temperature.