bluuebunny/crossref_metadata_2025 huggingface dataset:
Dissolution Behavior of Novolak/Dissolution Inhibitor Resist Systems in an Aqueous Base Developer
Authors: Schlegel Leo , Ueno Takumi , Shiraishi Hiroshi , Hayashi Nobuaki , Hesp Simon , Iwayanagi Takao
Published: February 2005

In order to understand the basic mechanisms working in the dissolution of novolak/dissolution inhibitor systems model compounds have been studied in terms of their dissolution inhibition capabilities. The influences of the structure of small size molecules on the inhibition effect were examined as well as the effects of the intramolecular composition and of the molecular weight of polymeric dissolution inhibitors. The role of the novolak type in the inhibition mechanism was also investigated. It was found that an amphiphilic character of the inhibitor molecule and an appropriate structure of the novolak matrix polymer are the most important features for systems with high dissolution inhibition capability. The intramolecular composition of polymeric dissolution inhibitors also has a strong effect, whereas the molecular weight of polymeric dissolution inhibitors has less influence.
A Study on Radical Fluxes in Silane Plasma CVD from Trench Coverage Analysis
Authors: Yuuki Akimasa , Matsui Yasuji , Tachibana Kunihide
Published: February 2005

The precursors of the a-Si:H film in SiH4 plasma-enhanced CVD are investigated by use of trench coverage analysis. The cross sectional profile of deposited film in a trench is simulated by a direct Monte-Carlo method using the radical sticking probability β as an adjustable parameter. A comparison with the experimental results has shown that the trench coverage profiles are reproduced well by the model if two kinds of radicals, i.e., SiH3 and SiH2, are deposited independently on the substrate with the respective sticking probabilities of 0.1 and 1.0. The experimentally observed dependence of the trench profile on the plasma condition can be explained by the change in the radical deposition ratio, which becomes SiH3/SiH2=1/1 in pure SiH4 at low rf power and decreases to 1/2-1/3 in SiH4 diluted in Ar at high rf power. The above change in the contribution of two kinds of radicals to the deposition is also supported by the chemical kinetic calculation of the gas phase reactions and the radical transport to the substrate.
Sulfonamide-Phenolic Resin Negative Resist for KrF Excimer Laser Lithography
Authors: Yamaoka Tsuguo , Nishiki Masashi , Jin Shun Ji , Kitamura Jun , Koseki Ken'ichi
Published: February 2005

It was found that aromatic sulfonamides offer a novel category of photosensitive compounds for negative resists. A photosensitive layer consisting of m-cresol novolak resin and an aromatic sulfonamide such as p-(tolyl sulfonyl)-aniline, benzene sulfonyl aniline, p-toluene sulfonamide or 4,4'-methylene-di(p-tolyl sulfonyl)-aniline is insolubilized in an aqueous base by exposure to deep-UV lights involving KrF excimer laser light. The negative resists exhibited the sensitivities (D
g

0.5) from 25 mJ/cm2 to 80 mJ/cm2 depending on the structure of sulfonamide. By exposure with a KrF excimer laser stepper 0.8 and 0.35 µm line patterns were transferred. The mechanism of the photoinsolubilization is also discussed.
Properties of Aluminum-Doped ZnO Thin Films Grown by Electron Beam Evaporation
Authors: Kuroyanagi Akio
Published: February 2005

Highly conductive thin films of ZnO have been prepared by conventional electron beam evaporation on glass substrates. The Al2O3 content of 0–5 wt% was added as dopant into ZnO to decrease resistivity of ZnO films. An Al-doped ZnO film with a resistivity of 1.0 × 10-3 Ωcm is obtained at a substrate temperature of 300°C with 1.0 wt% Al2O3 content; transmittance of this film is above 90% in the visible range with 100 nm thickness. The ZnO source material doped with Al2O3 is evaporated efficiently by a lower electron beam power compared to the case of nondoped ZnO. The c-axis orientation of ZnO films is facilitated by the addition of Al2O3 and the c-axis of Al-doped ZnO films is oriented perpendicular to glass substrates in the substrate temperature range of 60°C–350°C.
Structures and Nonlinear Optical Properties of Long-Alkyl MNA Films Prepared by the PVD Method
Authors: Inoue Takahito , Yase Kiyoshi , Okada Masakazu , Matsuda Hiro , Okada Shuji , Nakanishi Hachiro , Kato Masao
Published: February 2005

N-octadecyl-2-methyl-4-nitroaniline was evaporated onto KCl and glass substrates under a vacuum. Molecular orientation against the substrate surface was found to vary from lateral on KCl to normal on glass, and fine epitaxial crystal growth over the entire surface of KCl was observed at the substrate temperature of 50°C. It has been demonstrated that by third harmonic generation measurements using a polarized laser beam, the tilt angle of the 2-methyl-4-nitroaniline moiety in the unit cell can be determined.
Preparation and Electrical Conductivity of Li2O-V2O5-SiO2 Thin Films
Authors: Ohtsuka Hideaki , Yamaki Jun-ichi
Published: February 2005

Li2O-V2O5-SiO2, thin films were fabricated by the rf sputtering method. The X-ray diffraction patterns of the film annealed at 500–600°C agreed with the γ-Li3VO4 phase powder pattern. The as-sputtered film had an orientation of the (001) plane parallel to the substrate. The electrical conductivity of the annealed film was higher than that of the as-sputtered film. The conductivity was 4.8×10-3 S/m at 100°C, and the activation energy was 0.52 eV. The electronic transference number is 1.5×10-4.
Radiation Chemical Reaction and Submicron Pattern Fabrication on 10,12-Pentacosadiynoic Acid LB Films Using X-Ray Irradiation
Authors: Ogawa Kazufumi , Mino Norihisa , Tamura Hideharu
Published: February 2005

X-ray induced polymerization of 10,12-pentacosadiynoic acid (PDA) Langmuir-Blodgett (LB) films has been studied in relation to the molecular density or arrangement for use in X-ray resists. Two typical PDA LB films of different molecular densities were polymerized to form different polymer LB films by X-ray irradiation. The low-density PDA LB films (A type) were more sensitive than the high-density PDA LB films (B type) when X-ray was irradiated in helium atmosphere and the polymerization was caused topochemically on A-type film but not on B-type film. Decomposition of polymerized films was observed by excessive irradiation of X-ray for A-type film, but not for B-type film. Using both types of PDA LB films, 0.4 µm patterns could be fabricated by X-ray exposure.
A Method to Compensate Decay of Power in SR Lithography
Authors: Hasegawa Shinya , Atoda Nobufumi , Matsuo Koji , Itoh Junji
Published: February 2005

A method to compensate the synchrotron radiation power decrease due to the stored current decay by increasing the stored electron energy is described. The absorbed power in a resist can be held constant by about a 10 percent increase of the electron energy, compensating the beam current decrease of 50 percent. The throughput decrease is 10 percent owing to power suppression in order to maintain constant absorbed power.
X-ray Lithography: Novel Fabrication Process for SiC/W Steppermasks
Authors: Lüthje H. , Harms M. , Matthiessen B. , Bruns A.
Published: February 2005

This paper deals with the fabrication of an X-ray stepper mask based on a rigid SiC membrane and an almost stress free W absorber. As a result of extensive process optimization the poly-crystalline SiC membranes can be fabricated with a smooth surface (Rt<15 nm) and a Young's modulus as high as the bulk value (4.6×1011 N/m2). Membranes of 2.5 µm in thickness are being prepared routinely with excellent transparency for synchrotron and optical radiation. A proper stress adjustment of the SiC membrane can be either realized by an implantation of e.g. boron at a dose of 1015 cm-2 or by a thermal oxidation at 1100°C.
The W absorber technology enables absorber stresses of less than 1.107 N/m2, resulting in mask distortions of <100 nm for 25×25 mm2 step fields. Precise sub-0.5-micron pattern have been generated by use of e-beam lithography and RIE techniques. High doses SOR experiments indicate an excellent long-term stability of these SiC/W masks.
Simulation of X-Ray Mask Repair by Means of FIB-Technology
Authors: Müller Karl Paul
Published: February 2005

The angular dependence of the sputter yield of a 100 keV gallium FIB (focused ion beam) on gold was determined by evaluating the sufficient ion dose for complete removal of a 0.8 µm thick electroplated gold layer. For two angles of incidence (0°, 45°), the redeposition characteristics of sputtered gold particles were measured. They can be approximated by a cos2 function. With these data included, simulations of FIB-processes were carried out, both concerning the structuring of III-V compounds and the repair of opaque defects in X-ray masks. By parameter variation in the simulations, the sticking coefficient of sputtered gold particles was found to be µ=0.5±0.1.
MOS Gate Etching Using an Advanced Magnetron Etching System
Authors: Noda Shuichi , Nishikawa Satoshi , Ohno Seigo
Published: February 2005

A new type of magnetron etching system, RAMRIE, has been developed. Its characteristics for poly-Si gate etching with Cl2 has been investigated as a function of RF power and etching pressure in comparison with those for RIE whose structure and operating conditions are the same as those of RAMRIE. It was found that the profile of etched poly-Si is determined only by the etch selectivity of poly-Si to SiO2 (S
SiO) and that the pattern profile changes from an overhung shape to an undercut shape with increasing S
SiO for both systems. Good anisotropy was obtained with RAMRIE when S
SiO is about 20, which is two times as large as that with RIE. Under this condition, a 0.2 µm gate pattern was successfully delineated with RAMRIE. The characteristics of MOS capacitors prepared with RAMRIE and RIE have also been studied, but no etching-induced damage has been observed.
Induced Defects in GaAs Etched by Low Energy Ions in Electron Beam Excited Plasma (EBEP) System
Authors: Yu Jin-Zhong , Masui Norio , Yuba Yoshihiko , Hara Tamio , Hamagaki Manabu , Aoyagi Yoshinobu , Gamo Kenji , Namba Susumu
Published: February 2005

Ion beam etching (IBE) of GaAs with a source gas of Cl2 or Ar was carried out at a low energy ranging from 5 to 130 eV by using an electron-beam-excited-plasma system, and residual defect centers were investigated by means of deep-level transient spectroscopy (DLTS). Foul kinds of defect centers labeled L1 L2, L3, L5 with activation energies of 0.31, 0.45, 0.58, 0.48 eV, respectively, were resolved. Three of them were associated with damages induced by IBE and it was found that they have different thresholds for their generation, i.e., 60, 40 and 20 eV for L1, L2 and L3, respectively. It is necessary to reduce ion energy to less than 20 eV for perfect damage-free IBE of GaAs.
High-Quality p-Type a-SiC Films Obtained by Using a New Doping Gas of B(CH3)3
Authors: Tarui Hisaki , Matsuyama Takao , Okamoto Shingo , Dohjoh Hiroshi , Hishikawa Yoshihiro , Nakamura Noboru , Tsuda Shinya , Nakano Shoichi , Ohnishi Michitoshi , Kuwano Yukinori
Published: February 2005

High-quality p-type a SiC films can be fabricated by using a new type of doping gas, B(CH3)3, instead of B2H6 in a photo-CVD method and a glow discharge method. The photoconductivity and doping efficiency of a-SiC films fabricated by the photo-CVD method are improved by using B(CH3)3. A reduction of tail state density and an increase in photoluminescence are also observed. Furthermore, a bandgap narrowing in highly B-doped a-SiC films fabricated by the glow discharge method can be prevented by using B(CH3)3. A conversion efficiency of 10.0% (total area efficiency of 9.02%) is obtained for a 100 cm2 integrated-type a-Si solar cell whose p-layer was fabricated by the glow discharge method with B(CH3)3.
Vacuum UV Photoabsorption Spectra of Silane and Disilane: Molecular Orbital Calculation of Electronic States
Authors: Kawai Eikichi , Kasatani Kazuo , Kawasaki Masahiro , Sato Hiroyasu , Hirao Kimihiko
Published: February 2005

Ab initio molecular orbital calculations have been performed for the assignment of vacuum ultraviolet photoabsorption spectra of SiH4 and Si2H6. Strong peaks in the absorption spectra are primarily due to Rydberg transitions of the Si–H and Si–Si bonding electrons to the 4s, 4p, and 4d orbitals. Substantial contributions of the valence excitations are revealed.
Noncollinearly Phase-Matched Second Harmonic Generation in Stilbene-Dye-Attached Polymer Thin Films
Authors: Shuto Yoshito , Takara Hidehiko , Amano Michiyuki , Kaino Toshikuni
Published: February 2005

Noncollinearly phase-matched second harmonic generation (SHG) of Nd:YAG-laser light (1.064 µm) has been measured in a thin-film waveguide of stilbene-dye substituted methacrylate polymer on a glass substrate. The second-order nonlinear optical coefficient d
33 of the corona-poled film is 1.6×10-8 esu (at 1.064 µm). The phase-matching crossing angle of two guided fundamental beams is about 3.6° in the 1.38±0.02 µm-thick polymer waveguide. The SHG efficiency has been estimated to be about 5×10-5% for the fundamental peak power of about 130 W. The broad angular dependence of SH power has resulted from the short interaction length (0.1∼1 mm order) of two fundamental beams.
Third Harmonic Distortion of Dielectric Resonator Materials
Authors: Tamura Hiroshi , Hattori Jun , Nishikawa Toshio , Wakino Kikuo
Published: February 2005

Microwave dielectric materials must have a low third harmonic distortion when they are used for high-power applications. This is because the third harmonic distortion produces a third-order intermodulation distortion which generates interference between signals. In this paper, the measurement results of the third harmonic distortion levels for three types of dielectric resonator materials, (Zr, Sn)TiO4, MgTiO3-CaTiO3 and BaO-PbO-Nd2O3-TiO2, are reported and the equations derived to combine the distortion level and the fourth anharmonic term in the crystal's Hamiltonian. The measured distortion levels have a strong correlation with dielectric loss tangents of the materials. This relationship is also explained in connection with the anharmonic terms in the crystal's Hamiltonian.
Electrostatic Capacitance in Ferroelectric Smectic Liquid Crystal Cells
Authors: Kuwahara Michio , Minami Kouji , Kawata Yasushi , Onnagawa Hiroyoshi , Miyashita Kazuo
Published: February 2005

Contributions of spontaneous polarization (P
s) to capacitance (C) in ferroelectric liquid crystal (FLC) cells are analyzed in the present paper. Reorientation properties of FLC molecules have been studied on the basis of capacitance vs applied voltage characteristics. In the course of polarization reversal, C increases as the component of P
s parallel to the substrate of the cell becomes large.
AES Study of the Reaction between a Thin Fe-Film and β-SiC (100) Surface
Authors: Mizokawa Yusuke , Nakanishi Shigemitsu , Miyase Sunao
Published: February 2005

The solid state reaction between thin Fe-films and β-SiC (100) in UHV has been studied using AES. Even at room temperature, the reaction between the thin Fe-film and SiC occurred and formed Fe-silicide and graphite with a minor product of Fe-carbide (Fe3C). The reaction proceeded with an increase of Fe-coverage to some extent. With annealing of 15 Å-Fe-film/SiC below 540°C, the Fe-silicide formation was accelerated, but because the amount of available Fe was small, the dissolved carbon atoms were forced to form not the Fe-carbide but the graphite phase. Above 640°C, the Fe-silicide started to decompose and the carbon atoms diffused to the surface and formed surface graphite layers. With annealing at 1080°C, the free-Si segregated at the surface and formed Si-Si bonds, as well as the Si-C bonds consuming the surface graphite phase.
Numerical Studies on Divertor Plasmas in Helical Systems
Authors: Ueda Noriaki , Itoh Kimitaka , Itoh Sanae-I.
Published: February 2005

Scrape-off layer and divertor plasmas in helical systems are studied by using the two-dimensional (2D) numerical simulation code. Unified edge divertor analysis code (UEDA code) is applied to the straight helical model of torsatron/helical heliotron configurations. 2D profiles of plasma parameter, neutrals and impurities are obtained. Erosion rate and neutral back flow rate to the core plasma are also evaluated. Various shapes of the buffle plate are examined from the view point of the establishment of “dense-cold divertor plasma” by which we can avoid the damage of the target plate.
Simulation of Three-Dimensional Positive Photoresist Images
Authors: Barouch E. , Bradie B. , Babu S. V.
Published: February 2005

The least-action dissolution algorithm (LEAD) is applied to simulate three-dimensional positive photoresist images on reflective substrates. This algorithm avoids the ambiguities of the string algorithm and its modifications by utilizing the local validity of the eikonal description of the underlying diffusion equation to describe developer penetration with a moving boundary. The electric field and the concentration of the photoactive compound (PAC) within the photoresist film in the presence of standing waves in three dimensions are obtained from the numerically efficient WKB procedure proposed recently. The PAC concentration profile is combined with the LEAD algorithm to simulate a three dimensional one micron diameter contact hole in a single layer resist.
A Line Cathode Electron Gun of the Pierce-Type Design
Authors: Sugiyama Norio , Yokose Toyoji , Iwamoto Eiji , Uchikawa Yoshiki
Published: February 2005

An electron gun of the Pierce-type configuration with a line cathode of the same size as the electron beam required has been developed. A line-shaped beam measuring 1.1 mm×6.0 mm with a current efficiency of more than 99% was obtained. The electron gun was designed by computer simulation based on the electrolytic-tank method. Calculation within the gun revealed that a negatively biased focus electrode and a line cathode with a rectangular cross section are appropriate to obtain a line-shaped electron beam. Beam uniformity along the line is within ±6% in the middle part 5.0 mm long. The influence of the magnetic field due to the cathode heating current on the beam uniformity was investigated by beam trajectory tracing.
Field Enhancement of Photocurrent in a-SiN0.7:H
Authors: Maeda Keiji
Published: February 2005

Two kinds of centers with different barrier heights contribute to the Poole-Frenkel current in a-SiN0.7:H in a high electric field. Based on the characteristics of these centers, a field enhancement of photocurrent was expected and actually observed in the field where the Poole-Frenkel current flows in the dark. This phenomenon is due to field-assisted thermal ionization of the shallow center, which is occupied under the photoexcitation.
Effect of Depositing a-Si Thickness on Characteristics of Electric Double Probe Exposed to a Silane Plasma
Authors: Kudo Kouichi
Published: February 2005

To study the change in characteristics of a double probe exposed to silane plasma, we measured the V–I characteristics of a double probe for various a-Si thicknesses, and compared the experimental results with results calculated by a simple model. It is found that the change in V–I characteristics of the double probe was caused by the deposition of resistive material on probe surface, and it is expected that the change in the V–I characteristics of a double probe will be utilized to monitor the thickness of a-Si deposition.
Amphoteric Property of Electrically Active Nickel in Silicon
Authors: Kitagawa Hajime , Nakashima Hiroshi
Published: February 2005

Deep levels in nickel-doped n- and p-type silicon have been studied by the Hall effect and deep level transient spectroscopy (DLTS) under various diffusion and isothermal annealing conditions. It was found that nickel introduces an acceptor level of 0.47±0.04 eV from the conduction band and a donor level of 0.18±0.02 eV from the valence band, and that the concentrations of the two levels are practically identical. Isothermal annealing experiments have revealed stable behaviors of the two levels. The results suggest that the two levels are different charge states of the same substitutional nickel atoms in silicon.
Optimum Cell Design for High-Performance A-Si:H Solar Cells Prepared by Photo-CVD
Authors: Kim Woo-Yeol , Shibata Akio , Kazama Yoshiyuki , Konagai Makoto , Takahashi Kiyoshi
Published: February 2005

We have optimized the preparation conditions of p-i-n type a-Si:H solar cells prepared by photo-CVD. The pyramid-shaped SnO2 with haze ratio of 25% was chosen as the best TCO (transparent conductive oxide). The best efficiency obtained for a glass/TCO/p/buffer/i/n/Al structure of this type was 11.4% (V
oc=0.90 V, I
sc=17.86 mA/cm2, FF=0.706) for a 3×3 mm2 cell; the thicknesses of the p-, buffer-, i-, and n-layers were 50 A, 150 A, 7800 A, and 600 A, respectively.
Role of Rare Earth Ions (Gd, Dy, Ho and Er) in Phase Formation and Superconducting Properties of Ba1-xLnxCuO3-y Compounds
Authors: Ohshima Shigetoshi , Ishida Hiroyuki , Wakiyama Tokuo
Published: February 2005

Ba–Ln–Cu–O compounds (Ln=Gd, Dy, Ho and Er) were prepared by a solid-state reaction. The optimum sintering temperature for obtaining a single phase of Ba2LnCu3O7-δ was different for each Ln element, and this temperature decreased with increasing atomic number of Ln. A single phase with the perovskite structure was obtained only around the Ba2LnCu3O7-δ composition. T
c's of these compounds prepared by a solid-state reaction in air increased with increasing atomic number of Ln. T
c's of samples prepared in oxygen atmosphere were almost the same. The magnetic moment of Ba1-x
Ln
x
CuO3-y
compounds is associated with each Ln, and its value is in good agreement with the Ln3+ Hund rules free ion values.
High-Energy Ion Beam Analysis of YBa2Cu3Ox Thin Films
Authors: Watamori Michio , Oura Kenjiro , Shoji Fumiya , Yotsuya Tsutomu , Ogawa Soichi , Hanawa Teruo
Published: February 2005

The composition and crystalline structure of high-T
c superconducting YBa2Cu3O
x
thin films formed on MgO(100) and Si(100) substrates have been investigated by Rutherford backscattering and channeling techniques. Y, Ba, Cu contents have been analyzed by employing a high-energy (over 4.5 MeV) 4He ions and large scattering angle (near 170°) condition, where Y, Ba and Cu peaks are clearly separated from each other. Oxygen concentration has been obtained through the use of low primary energy (below 2.5 MeV) and small scattering angle (below 150°) conditions, where the O peak is separated from the background. The crystalline quality of the films has also been investigated by ion channeling techniques.
Soft Magnetic Properties and Magnetic Anisotropy Dispersions of Fe–Ni/Ni–Fe Multilayered Films
Authors: Nakatani Ryoichi , Kobayashi Toshio , Ootomo Shigekazu , Kumasaka Noriyuki
Published: February 2005

Fe–2 at.%Ni/Ni–20 at.%Fe multilayered films are formed by the ion beam sputtering method. Their magnetic properties and magnetic anisotropy dispersions are examined. The Fe–Ni/Ni–Fe multilayered film of a 25 nm period displays a relative permeability of 1300 and a saturation magnetic flux density of 1.9 T. As the period of Fe–Ni/Ni–Fe multilayered films is reduced, the Fe–Ni crystallite size and the magnetic anisotropy dispersion become smaller, resulting in good soft magnetic properties.
Segregated Microstructure and Crystal Structure in Sputter-Deposited Co–Cr Carbon-Added Films
Authors: Masuya Haruko , Awano Haruo
Published: February 2005

The compositionally segregated microstructure and the crystal structure of sputter-deposited Co–Cr films to which various percentages of carbon were added are studied by transmission electron microscopy. The results are as follows:
(1)  The degree of segregation in the microstructure increases as amount of carbon added increases. The segregated pattern is changed by the amount of carbon added.
(2)  The saturation magnetization increases as the degree of the segregation increases. The perpendicular coercivity depends on the perpendicular magnetic anisotropy, and magnetic anisotropy is related to the degree of segregation and the refinement of the segregated pattern.
(3)  The plane defects perpendicular to the C-axis in sputter-deposited Co–Cr films are grown by carbon addition.
Molecular Motions and Mechanical Relaxations of Poly(Carbonate) in the Glassy State
Authors: Kakizaki Maeko , Tanimoto Morimasa , Hideshima Teruo
Published: February 2005

In order to determine the characteristics of the glassy-state relaxations of poly(bisphenol-A carbonate) which are closely overlapping each other, shear relaxation modulus was measured from 10 sec to 900 sec at temperatures ranging fromca. -180°C to 0°C. Three relaxations named β, γ and δ in the order of descending temperature were observed separately and master curves were determined by the method of reduced variables. The activation energies of the β, γ and δ relaxations were estimated to beca. 30, 25 and 9 kcal/mol, respectively. Theoretical considerations suggest that the molecular motions for the β, γ and δ relaxations are the local-mode motion of main chain, the flip motion of a phenylene with a carbonate group, and the rotational motion of a pair of methyl groups belonging to neighboring chains and coupled by van der Waals force.
Epitaxial Lateral Overgrowth of Si by LPE with Sn Solution and Its Orientation Dependence
Authors: Suzuki Yoshiyuki , Nishinaga Tatau
Published: February 2005

A single crystal Si layer was grown over SiO2 film by epitaxial lateral overgrowth (ELO) using LPE, and the dependence of the ratio of the lateral to the vertical growth rates on crystal orientation was investigated. Sn was used as a solution, and it was found that the growth surface was flat and completely mirror like. The lateral growth had a singularity when the line seed was aligned in just the <110 > orientation, but it was almost constant when the orientation was varied around the <112 > orientation. The time dependence of the growth was investigated, and it was found that both the lateral width and the vertical thickness were approximately proportional to t
1/2, and the volume of the growth was proportional to t
0.9. Sirtl etch revealed that almost no etch pits were observable on the ELO layer. This result shows that ELO by LPE yields SOI films with an extremely good crystal quality.
Boundary and Initial Conditions of Approximate Diffusion Equation for Gold in Silicon
Authors: Morooka Masami , Yoshida Masayuki
Published: February 2005

In the basic partial differential equations for diffusion of gold in dissociative and kick-out mechanisms, substitutional gold, interstitial gold, vacancies and self-interstitials are taken into consideration. It takes a long time to solve these equations numerically. It is therefore convenient to solve the approximate partial differential equation for substitutional gold, which is obtained after the reactions between these four elements have reached their local equilibrium states and the interstitial gold has reached its thermal equilibrium state, under suitable boundary and initial conditions.
In the in-diffusion process, the conditions of the approximate equation are different from those of the basic equations. In the annealing process, the conditions are the same for the basic and the approximate equations.
Quick Deposition of ZuS:Mn Electroluminescent Thin Films by Intense, Pulsed, Ion Beam Evaporation
Authors: Shimotori Yutaka , Yokoyama Meiso , Harada Shigetoshi , Masugata Katsumi , Yatsui Kiyoshi
Published: February 2005

Electroluminescent ZnS:Mn thin films have been guickly deposited by a high-density, high-temperature plasma produced by the irradiation of an intense (>GW/cm2), pulsed (∼tens of ns) ion beam onto a ZnS:Mn target. The films prepared on a glass substrate have a polycrystalline hexagonal structure. The temperature of the target plasma was estimated to be ∼2.7 eV, where the plasma was highly ionized. The instantaneous deposition rate was estimated to be ∼4 cm/s, which is at least five orders of magnitude higher than that of any other conventional evaporation techique. We have prepared a ZnS:Mn electroluminescent device with a luminescent layer having a thickness of ∼200 nm. The device has a threshold voltage of ∼80 V0p (zero to peak value). The maximum luminance of 195 cd/m2 has been obtained under 10 kHz sinusoidal excitation at 144 V0p.
Temperature Dependence of Photoacoustic and Photoluminescence Signals for CdSxSe1-x Microcrystals
Authors: Umezu Ikurou , Ogawa Tsutomu , Arai Toshihiro
Published: February 2005

Temperature dependence of absorption, photoacoustic(PA), photoluminescence excitation(PLE) and photoluminescence(PL) spectra were measured for filter glasses which include sulfur-rich CdS
x
Se1-x
microcrystals. Absolute quantum efficiency for radiative recombination was obtained by comparing photoacoustic spectra with photoluminescence spectra. Quantum efficiency of radiative recombination for small microcrystals is found to be higher than that for large microcrystals. By solving the rate equations, very small band-to-band nonradiative transition was suggested in these microcrystals. We regarded this as the main reason for the large quantum efficiency.
Effect of Size Confinement on the Electronic States of CdS Cluster in a Germanium Oxide Matrix
Authors: Arai Toshihiro , Fujumura Hidehiko , Umezu Ikuro , Ogawa Tsutomu , Fujii Americo
Published: February 2005

Change in the electronic state due to size confinement was studied for the CdS cluster embedded in GeO2 glass by photoacoustic, optical absorption and photoluminescence spectroscopies. The cluster size increases with increasing annealing temperature and time. The activation energy of ion diffusion during cluster growth is 0.45 eV. When the cluster size becomes less than about twice the exciton size, the energy bands become discrete. The energies of 1st and 2nd excited states increase with decreasing cluster size. The size dependence of the ist excited state determined experimentally coincides with the calculation. The energy of the surface state also shifts in parallel with the shift of the 1st excited state. When the cluster size decreases, the intensity of the edge emission decreases faster than that of the surface emission.
Timing Properties of a Time-of-Flight Detector
Authors: Nakagawa Takahide , Yuasa-Nakagawa Keiko
Published: February 2005

The time resolution of a time-of-flight (T.O.F.) detector which consists of a channel plate detector (CPD) with a central hole and a surface barrier detector (SBD) was measured. A time resolution of 80 psec fwhm was obtained for 8.78 MeV alpha particles. The influence on fast timing of the SBD of alpha particles was carefully studied. The plasma delay time and time resolution of the SBD were found to strongly depend on the electric field strength and properties of the SBD.
Investigation of Switching Behavior in a Ferroelectric Liquid Crystal Aligned on Obliquely Deposited SiO Films
Authors: Yamada Yuichiro , Yamamoto Norio , Inoue Tetsuya , Orihara Hiroshi , Ishibashi Yoshihiro
Published: February 2005

The effect of oblique evaporation of SiO on the chevron structure and the switching behavior in a ferroelectric liquid crystal have been investigated by means of the X-ray diffraction and the stroboscopic micrographs. It is found experimentally that the chevron direction and the domain structure appearing during the switching are determined by the direction of incidence of evaporated SiO. On the basis of the experimental results, it is clarified that the bow and the stern of the boat-shaped domain correspond to +2π and -2π internal disclinations, respectively. The structure of the zig-zag defect is determined.
Electrical Conductivity of Polypyrrol-Films as Affected by Adsorption of Vapors
Authors: Rabe Johann Georg , Bischoff Gerlinde , Schmidt Werner F.
Published: February 2005

Chemically prepared polypyrrole films were exposed to vapors of sulfur dioxide, methyl amine, ammonia, and water. The resulting increase in electrical conductivity was measured as a function of the partial pressure. The results are discussed on the basis of the modification of the polymer surface layer by adsorption of molecules and subsequent electron transfer.
Ferroelectric Liquid Crystal Display with High Contrast Ratio
Authors: Yamamoto Norio , Yamada Yuichiro , Mori Kahoru , Orihara Hiroshi , Ishibashi Yoshihiro
Published: February 2005

To obtain zig-zag defect-free liquid crystal cells by means of a standard rubbing technique, the effect of a new polyimide film on pretilt angle at a surface has been investigated. This new polyimide imposes the high pretilt over wide rubbing density, and good orientation of liquid crystals without zig-zag defects can be obtained for rubbing densities higher than 0.5×103. A new driving scheme to realize display devices with a high contrast ratio is proposed. This scheme is devised by utilizing anomalous switching behavior and AC-stabilized effect. The prototype of the ferroelectric liquid crystal display device shows the maximum contrast ratio of 40:1.
Activation Energies for Electrode Reaction of Metal Hydride in Alkaline Aqueous Solution
Authors: Yayama Hideki , Tomokiyo Akihisa , Hirakawa Kazuyoshi
Published: February 2005

Electrolyses by a TiMn1.5Hxelectrode in alkaline aqueous solution were carried out at various temperatures under constant-current and constant-potential conditions. The electrode resistance increased with decreasing temperature. The activation energies for the charge transfer process and for the diffusion of hydrogen were obtained. The increase in electrode resistance with decreasing temperature was attributed largely to the temperature dependence of the charge transfer rate rather than to that of the diffusion rate of hydrogen.
High-Aspect-Ratio Alkaline Surface Treatment Method of Dyed Photoresist
Authors: Endo Masayuki , Sasago Masaru , Matsuoka Kouji , Nomura Noboru
Published: February 2005

Contrast enhancement by alkaline surface treatment of dyed photoresist is characterized. A surface-modified layer formed by the alkaline surface treatment prevents unexposed areas of the resist from being dissolved and acts as a barrier during development. Utilizing alkaline surface treatment, high-aspect-ratio submicron patterns on a highly reflective substrate are successfully delineated with negligible resist thickness loss. It is found that this modified process is enhanced by baking before exposure.
Photoluminescence from Highly Be-Doped AlGaAs Grown by MBE
Authors: Morita Masahiko , Kobayashi Kikuo , Suzuki Takeo , Okano Yoshimichi
Published: February 2005

The photoluminescence (PL) of Be-doped Al
x
Ga1-x
As grown by MBE for Al contents 0.20<x<0.88 and hole concentrations 5×1018<N
h< 1.5×1019 cm-3 has been measured at 77 K. PL spectra for higher x's suggest the presence of deep levels. The formation of deep levels associated with interstitial Be is discussed.
Assessment of the Method for Determining the Elastic Constant Ratios in Nematics by Angular Dependence of Scattered Light Intensity
Authors: Chen Guo-Ping , Takezoe Hideo , Fukuda Atsuo
Published: February 2005

To assess the Rayleigh light scattering method as a means to determine the elastic constant ratios, we have first reviewed the de Gennes formula for the differential cross section, reexamining the assumptions used and the corrections at the interfaces. Then we have summarized optimum scattering geometries, proposing a new geometry suitable for obtaining K
11/K
33 directly. Finally we have described experimentals; considerable emphasis has been laid on the stray light level and the delicate adjustment of the experimental setup in determining K
11/K
22 and K
33/K
22. The data in each measurement showed a roughly ±3% deviation and there were systematic differences between the three independent measurements.
The de Gennes formula appears to be reliable and suitable scattering geometries do in fact exist for obtaining each K

i
i
/K

j
j
. Accurate determination is prevented by experimental annoyances. The method is inherently susceptible to stray light and the measurement requires delicate critical adjustments of the optical system. The delicacy required for the operation and the susceptibility to stray light may cause the introduction of systematic errors. Photon correlation spectroscopy expected to be resistant to these errors has been suggested for use in determining not only viscosity but also elastic constant ratios.
Improvement in Detection Limit of Electric Field Measurement Using Optogalvanic Signals by Laser Excited Rydberg Atoms
Authors: Yamagata Yukihiko , Suenaga Kiyoyuki , Muraoka Katsunori , Maeda Mitsuo , Akazaki Masanori
Published: February 2005

Optogalvanic signals, caused by laser-excited Rydberg atoms, were measured to estimate the electric field in a DC glow discharge in helium. With a careful analysis of the various factors limiting the detection limit and an experiment to check the analysis, the detection limit of an electric field of 21.5 V/mm was obtained which was limited by the laser spectral width.
Polycrystalline Silicon Film Formation at Low Temperature Using a Microcrystalline Silicon Film
Authors: Nakazawa Kenji , Tanaka Keiji , Yamauchi Noriyoshi
Published: February 2005

Polycrystalline silicon (polysilicon) films are formed from the recrystallization of microcrystalline silicon films with different crystalline nucleus densities. The films are deposited by plasma CVD using a gas mixture of SiH2F2, SiH4, and H2. The SiH2F2 flow rate can successfully control the crystalline nucleus density of an as-deposited film. The recrystallization is carried out by annealing at 600°C. The TEM observation shows that recrystallization proceeds from the nucleus until the neighboring grains face each other. Therefore, the grain size in the annealed films and the field effect mobility of thin film transistors using polysilicon films completely depend on the crystalline nucleus density in the starting films. The largest grain sizes and highest field effect mobilities can be obtained from microcrystalline silicon films with the lowest nucleus densities.
Interconnection Technology for Three-Dimensional Integration
Authors: Mitsuhashi Katsunori , Yamazaki Osamu , Ohtake Koui , Koba Masayoshi
Published: February 2005

The technology of thermally stable and fully planarized multilevel interconnections with selective CVD-W vias and 31P+/11B+ implanted WSi
x
/TiN/Si contacts has been developed for three-dimensional VLSIs. Via holes with high aspect ratios (about 3) and different depths (0.8–3.0 µm) were completely filled by selective W-CVD and subsequent etch-back, and the surface was planarized to below 0.2 µm using a previously reported interlevel insulation planarization technology. Metal-silicon reactions during high-temperature annealing were eliminated by the use of a TiN thin film (0.08 µm) containing oxygen as a diffusion barrier. By performing an additional 31P+ and 11B+ implantation into the interconnection, the ohmic contacts to n
+ and p
+ Si in this structure were also maintained even after annealing at 900°C for 6 hours.
Photoluminescence Centers in VAD SiO2 Glasses Sintered under Reducing or Oxidizing Atmospheres
Authors: Kohketsu Masami , Awazu Koichi , Kawazoe Hiroshi , Yamane Masayuki
Published: February 2005

Two types of diamagnetic luminescence centers were found in VAD SiO2 glass sintered under reducing atmospheres. One of the PL centers, which had an excitation band at 5.17 eV (240 nm) and two emission bands, at 4.2 eV (295 nm) and 3.1 eV (400 nm), was mainly detected in the glasses sintered under H2/He atmosphere. The intensity of the luminescence increased with the partial pressure of hydrogen of the atmosphere. The other PL center, which had an excitation band at 5.06 eV (245 nm) and at least two emission bands at 4.2 eV (295 nm) and around 3.0 eV (413 nm), has been predominantly observed in the sample melted under vacuum. On the basis of the atmosphere dependence of PL and optical absorption measurements in the VUV region, the former was assigned to Si (II) dissolved in a silica network. The Si cluster, in which the number of direct Si-Si bonds exceeded 4, was proposed as a possible candidate for the latter.
Photoluminescence in VAD SiO2:GeO2 Glasses Sintered under Reducing or Oxidizing Conditions
Authors: Kohketsu Masami , Awazu Koichi , Kawazoe Hiroshi , Yamane Masayuki
Published: February 2005

The atmosphere dependence of photoluminescence (PL) centers produced in SiO2:GeO2 glasses was examined by preparing VAD SiO2:GeO2 preform rods with changing the sintering atmosphere systematically from reducing to oxidizing. Four types of luminescence centers could be detected for samples sintered under H2/He=1/20, He or O2/He=1/10 atmospheres. The atmosphere dependence of luminescence intensity suggests that reduced species of Ge and/or Si are responsible for the luminescence centers. Ge(II) dissolved in a SiO2 network, which was characterized as a lone pair of electrons located on a Ge atom with 2 or 3 oxygen neighbors. Si(II) dissolved in a silica network, and the Si and/or Ge cluster and [chemical formula] or [chemical formula] were proposed for the possible structural models of PL centers.
Extremely Long-Lived Residual Photocurrent in Amorphous In2Se3 Films
Authors: Watanabe Ichiro , Sekiya Toshiyuki
Published: February 2005

A large photoconduction has been observed in amorphous In2Se3 films. The films exhibit residual photocurrent with an extremely slow decay rate after stopping of a steady illumination by band gap light. They also exhibit photocurrent with an extremely slow rising rate after initiation of the illumination. The extremely slow decay and rising are explained by a model in which the illumination creates neutral defects through any structural change, the photocurrent is derived from the variable range hopping between the photocreated defect levels, and the photocreated defects decay according to the monomolecular reaction with a thermally activated decay rate.
Al Impurity Purification in Quartz Grown by the Hydrothermal Method
Authors: Iwasaki Fumiko , Iwasaki Hideo , Suzuki Carlos K.
Published: February 2005

Al impurity purification in synthetic quartz grown by the hydrothermal method was studied by atomic absorption spectroscopy. The purification process can be expressed by the equation. Alsq=a· exp
(b·Allasca), with Alsq and Allasca representing the respective Al contents in synthetic quartz and lascas used as the nutrient. a and b are constants which depend on the growth condition. Analytical data showed different Al content depending on growth region: it was highest in the S-region and lowest in the Z-region. Al content in the Z-region did not significantly differ (∼10 ppm), when the nutrient used for crystal growth had an Al content of between 29 ppm and 240 ppm. S-regions were not purified when the nutrient with Al content of less than 30 ppm was used. Influence of Al content on crystal morphology in the purification process was discussed.
Ultraviolet Light Irradiation Effects on Silicon Doping of GaAs Grown by the Triethylgallium-Arsine OMVPE Method
Authors: Mashita Masao
Published: February 2005

The silicon doping of low-pressure OMVPE GaAs has been studied using disilane (Si2H6) as a doping source. Triethylgallium (TEG) and arsine (AsH3) are used as starting materials. A 240–300 nm ultraviolet (UV) light irradiation has been found to enhance silicon doping, though the UV light wavelengths are longer than the absorption edge (200 nm) of Si2H6. The doping enhancement increases with a decrease in the substrate temperature below 700°C. The temperature dependence of the doping enhancement strongly differs from that for the case using trimethylgallium (TMG). From quadrupole mass spectrometer (QMS) analysis of gases in the reactor, it has been found that the doping enhancement corresponds closely to the amount of reaction products, (C2H5)
n
SiH4-n
(n=1–3). A doping enhancement mechanism, including radical generation, is discussed.
Self-Development Properties of Nitrocellulose (Dependence on Ion Species)
Authors: Kaneko Hidehiko , Yasuoka Yoshizumi , Gamo Kenji , Namba Susumu
Published: February 2005

Self-development properties (etch rate and formation of non-volatile residue) of nitrocellulose when it was exposed to various 50 keV ions (N+, Ne+, Ar+, Kr+ and Xe+) were studied. A maximum etch rate was obtained for the irradiation of Ar+. It was found from the results of the Auger electron spectroscopy that the irradiation of ions lighter than Ar+ (N+ and Ne+) caused a carbon-rich residue. The relationship between the experimental results and the calculated ion penetration depth and the energy deposition density is discussed.
Effects of Dipping in an Aqueous Hydrofluoric Acid Solution before Oxidation on Minority Carrier Lifetimes in p-Type Silicon Wafers
Authors: Shimizu Hirofumi , Honma Noriaki , Munakata Chusuke
Published: February 2005

A scanning photon microscope is successfully applied to measure ac surface photovoltages which correspond to apparent minority carrier lifetimes (τPCD) measured by the microwave-detected photoconductive decay (µ-PCD) method, using oxidized p-type silicon wafers pre-treated with or without dipping in an aqueous hydrofluoric acid (HF) solution. The dipping in HF solution causes a larger fixed oxide charge, resulting in a strongly inverted layer beneath the oxide. This situation gives longer τPCD than the bulk lifetime (τPV) by an ac photovoltaic method, while if the fixed oxide charge is small, τPCD gives an apparently smaller lifetime than τPV, implying that τPCD is influenced by the surface charge state or the surface potential. Hence, the process diagnosis by lifetime requires the measurements by both surface photovoltages and the µ-PCD method.
Copper-Related Deep Levels and Their Annealing Kinetics in Germanium
Authors: Kamiura Yoichi , Hashimoto Fumio
Published: February 2005

Four copper-related hole traps, H1(0.04), H2(0.09), H3(0.23) and H4(0.33), have been observed in heat-treated germanium by deep-level transient spectroscopy. H1 and H4 traps are identified as singly and doubly ionized acceptor levels of substitutional copper, Cus. Annealing around 200°C caused annihilation of H2 and H3 traps with a correlated increase in Cus density. Annealing kinetics have been studied by analyzing resistivity data by the reaction scheme, H2\rightleftharpoonsCus+H3 and H3→sinks (dislocations and the sample surface). This analysis has the yielded 6×10-3 exp
(-0.35[eV]/k
T) cm2s-1 for the diffusion coefficient of the H3 trap, which agrees well with that of the interstitial copper, Cui, determined by previous tracer experiments. From this and the donor character of the H3 trap, we have identified the H3 donor and H2 acceptor as Gui and the Gui–Gus pair, respectively.
Radicals' Emissions and Butane Diffusion Flames Exposed to Upward-Decreasing Magnetic Fields
Authors: Aoki Takashi
Published: February 2005

A diffusion flame of nonpremixed butane gas was exposed to upward-decreasing magnetic fields. Increases in emission intensities of OH*, CH* and C2
* radicals' transitions, an increase in the flame temperature, a decrease in the flame dimension, and a bluing tendency of the flame occurred. The magnetic gradient field affected C2
* the most, CH* somewhat less, and OH* the least. The emission intensity of a continuous spectrum decreased drastically with increasing magnetic gradient field. This means that the reaction liberating carbons decreased. The Lorentz force had no significant effect on flame shape changes. Magnetic forces originating from the magnetic gradients accelerated, stretched and squeezed the flame, resulting in a change in the flame shape. An attempt is made to explain the combustion changes by a simplified diffusion model based on changes in a mixing condition and a diffusion coefficient.