bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of Highly Conductive p-Type ZnSe Using Li3N Diffusion
Authors: Honda Tohru , Lim Sung Wook , Yanashima Katsunori , Inoue Kousuke , Hara Kazuhiko , Munekata Hiro , Kukimoto Hiroshi , Fumio Koyama Fumio Koyama , Kenichi Iga Kenichi Iga
Published: October 2002

We have achieved high concentration p-type doping of ZnSe grown by metalorganic vapor phase epitaxy using a Li3N diffusion technique. The average hole concentration in the ZnSe : (Li, N) layer formed at a diffusion temperature of 470° C was as high as 1×1018 cm-3, and the layer exhibited a resistivity of ρ=0.3 Ω· cm and a hole mobility of µ p=18 cm2/V·s.
Photoreflectance and Photoluminescence Characterization of GaAs Quantum Wells Grown by Molecular Beam Epitaxy on Flat and Misoriented Substrates
Authors: Meléndez-Lira Miguel , Máximo López-López Máximo López-López , Isaac Hernández-Calderón Isaac Hernández-Calderón
Published: October 2002

Photoreflectance (PR) and photoluminescence (PL) spectroscopies were employed in the characterization of molecular beam epitaxially grown GaAs/AlGaAs quantum wells grown on nominally flat (100) oriented and (100) misoriented GaAs substrates. Four quantum wells with nominal thickness of 100, 75, 50 and 25 Å were grown employing different temperatures between 600 and 650° C and growth rates of 0.5 and 1 µ m/h. Room temperature PR allowed us to obtain the actual aluminum composition (x=0.27), and obtain the magnitude of the interfacial electric field ( ∼106 V/cm). An evaluation of the abruptness of the quantum well interfaces was done from the analysis of PL and PR spectra in terms of the finite quantum well theory. The overall results clearly indicated that the step-flow growth mode on the misoriented substrate produced superior crystallinity of the heterostructures. In the case of growth on flat substrates higher temperatures and slower growth rates gave broader interfaces and thinner wells.
Sol–Gel Derived Pb(Zr,Ti)O3 Thin Films: Effects of PbTiO3 Interlayer
Authors: Jiin-Jyh Shyu Jiin-Jyh Shyu , Po-Chien Lee Po-Chien Lee
Published: October 2002

Pb(Zr,Ti)O3 films with PbTiO3 interlayers between the film and Pt/Ti/SiO2/Si(100) substrate were fabricated by using a sol–gel spin-on process. Effects of the PbTiO3 interlayer on the phase formation and electrical properties were investigated. A thin PbTiO3 interlayer of about 0.05 µ m is required to effectively enhance the perovskite formation of the Pb(Zr,Ti)O3 films, while a thicker PbTiO3 interlayer limits the perovskite formation. The glass-to-pyrochlore transformation is not significantly influenced by the PbTiO3 interlayer. Doping of La into the PbTiO3 interlayer elevates the perovskite formation temperature. The characteristics related to morphotropic phase boundary of the films are significantly weakened by the PbTiO3 interlayer. The fatigue behavior of the films is generally improved by the PbTiO3 interlayer. It is suggested that atomic diffusion between the Pb(Zr,Ti)O3 film and PbTiO3 interlayer influences the observed electrical properties.
Polymer Network Formed in Liquid Crystals: Polymer-Network-Induced Birefringence in Liquid Crystals
Authors: Fuh Andy Ying-Guey , Ming-Shann Tsai Ming-Shann Tsai , Chi-Yen Huang Chi-Yen Huang
Published: October 2002

A monomer with reactive double bonds was mixed with a liquid crystal and polymerized under UV irradiation in various phases of the liquid crystal. The polymer networks formed are found to be anisotropic and fiber-like, if the monomer is polymerized in an oriented liquid crystal state. The orientational order of the polymer network is shown to depend on that of the liquid crystal. After polymerization, the polymer network, in turn, is found to affect the orientation of the liquid crystal significantly. It induces birefringence in nematics at temperatures just above the nematic-isotropic phase transition.
Orientation of Liquid Crystal Molecules on Side-Chain Polyimide Alignment Layer Studied by Second-Harmonic Generation Interferometry
Authors: Takahiro Sakai Takahiro Sakai , Koichiro Shirota Koichiro Shirota , Toshiki Yamada Toshiki Yamada , Hajime Hoshi Hajime Hoshi , Ken Ishikawa Ken Ishikawa , Hideo Takezoe Hideo Takezoe , Atsuo Fukuda Atsuo Fukuda
Published: October 2002

Second-harmonic generation (SHG) interferometry has been applied to determine the phase of SHG from an SHG-active side-chain polyimide (PI) alignment layer with SHG-active liquid crystal molecules evaporated onto it. The phase difference between SH waves from the PI layer and from the PI layer with evaporated LC molecules monotonically increases with increasing evaporation time, while the SHG intensity increases after an inital decrease. These two facts indicate that LC molecules are adsorbed with an antiparallel polar orientation with respect to the polar side-chain orientation. The applicability of this method in studying the orientational relationship between an alignment layer and a LC monolayer is pointed out.
Micromechanics in Solder Materials Used for Microelectronic Applications
Authors: Seong-Min Lee Seong-Min Lee
Published: October 2002

In my previous articles I reported that, in solder materials subjected to mechanical fatigue under low-frequency conditions (f<10-3/ s) where intergranular failure occurs, there is some evidence that the grain, or colony, boundaries undergo sliding. To develop a better understanding of this phenomenon, the correlation between grain boundary orientation and intergranular cracking was investigated by examining cross sections of cracked grain boundaries in eutectic bulk solders subjected to tension-compression. A statistical picture of crack propagation was developed to provide evidence for the shear mechanism, which showing that there is a favored boundary orientation with respect to the surface of the specimen and the stress axis.
Photobleaching Process in Polysilane Films
Authors: Hideki Hayashi Hideki Hayashi , Tetsuya Kurando Tetsuya Kurando , Kunio Oka Kunio Oka , Takaaki Dohmaru Takaaki Dohmaru , Yoshikazu Nakayama Yoshikazu Nakayama
Published: October 2002

The thermally assisted photoscission model has been formulated to explain the photobleaching of polysilane films due to the photoinduced annihilation of σ bonds. In the model, σ bonds are photoexcited and then scissored with thermal assistance, and the photobleaching by means of a prolonged exposure to ultraviolet light leads to the formation of a sponge-like structure. The model predicts that (i) the decay of the photon flux absorbed in the films after t
T, defined as the time when the transmittance of the films begins to increase significantly, obeys a power law with an exponent of γ=k
T/ε
0, where ε
0 is the exponential width of the activation-energy distribution and k
T is the thermal energy; (ii) t
T is inversely proportional to the incident photon flux and obeys a power law against the film thickness with an exponent of 1/γ; and (iii) the temperature dependence of t
T provides the cross section of the photoexcitation of σ bonds C
r. It has been confirmed that these predictions are fairly consistent with the experimental results. The parameters of ε
0 and C
r for the photobleaching of poly(methylphenylsilane) films by 325 nm light have also been estimated to be 28 meV and 1.1×10-16 cm2, respectively.
Down to 0.1 µm Pattern Replication in Synchrotron Radiation Lithography
Authors: Yamashita Mitsuaki Morigami , Nishino Junichi , Yamaoka Yoshikazu , Nakao Masao
Published: October 2002

We studied sub-quarter- to sub-0.1-µ m pattern replication characteristics in synchrotron radiation (SR) lithography using a highly accurate low-contrast mask. AZ-PN100 (a chemical amplification negative-type resist) has a wide exposure latitude of more than ±10% for lines and spaces down to 0.12 µ m at a post exposure baking temperature of 110° C. Lines and spaces down to 0.1 µ m were clearly replicated in AZ-PN100. Sub-0.1-µ m lines and spaces and various types of pattern with 0.1 µ m features were successfully replicated in ZEP-520. These results indicate that SR lithography has potential for 0.1-µ m pattern replication. Insufficient mask linearity reduced the common exposure latitude. However, the mask feature bias technique can be used to expand the common exposure latitude.
Influences of Cu and Fe Impurities on Oxygen Precipitation in Czochralski-Grown Silicon
Authors: Shen Bo , Jablonski Jaroslaw , Takashi Sekiguchi Takashi Sekiguchi , Koji Sumino Koji Sumino
Published: October 2002

Characteristics of oxygen precipitation in Czochralski-grown silicon (CZ-Si) intentionally contaminated with Cu or Fe are investigated by means of Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), electron-beam-induced-current (EBIC) mapping and etch pit observation. It is found that oxygen precipitation is not influenced by the presence of Cu impurities, while it is enhanced significantly by the presence of Fe impurities even if the concentration of Fe is much lower than that of Cu. Precipitations of supersaturated Cu and O impurities are found to proceed independently of each other in Si crystals. Oxygen precipitates in an Fe-contaminated specimen are much denser and smaller than those in a noncontaminated specimen. Fe impurities seem to react with minute Si oxide particles which are present in as-grown CZ-Si crystals and reduce the nucleation barrier for oxygen precipitation.
Readout Scheme by Pulsed Irradiation Center Aperture Detection on Magnetically Induced Super Resolution Magnetooptical Disks
Authors: Yang Bor-Wen , Wein-Kuen Hwang Wein-Kuen Hwang , Han-Ping D. Shieh Han-Ping D. Shieh
Published: October 2002

Magnetically induced super resolution (MSR) is used to read “below-diffraction-limit” recording marks on magneto-optical (MO) media. A nanosecond-order laser pulse irradiated onto MO media can create a quasi-circular temperature profile, thereby yielding a quasi-circular sub-µ m aperture to effectively derive a readout signal from sub-µ m marks recorded on the disks. In this study, the pulsed irradiation and conventional DC readout methods are applied to a MO disk with a center aperture detection (CAD) structure to quantitatively evaluate their readout performance. The size and shape of the effective aperture, jitters due to readout parameters, and aperture wall width generated are studied. The feasibility of the pulsed irradiation readout is then assessed.
Properties of S Implanted in GaAs Activated Using As-Doped a-Si:H Encapsulant Films
Authors: Masanori Sakaguchi Masanori Sakaguchi , Katsuhiro Yokota Katsuhiro Yokota , Akira Shiomi Akira Shiomi , Kiyohito Hirai Kiyohito Hirai , Hiromichi Takano Hiromichi Takano , Masao Kumagai Masao Kumagai
Published: October 2002

Implantation of S+ ions into GaAs was performed under the conditions of energy of 120 keV and doses of 3×1013–1×1015 cm-2. The GaAs was capped with an 80 nm thick a-Si:H film into which As was doped at a concentration of 2×1020 cm-3. Then, the samples were annealed in Ar gas at 850–1000°C for 15 min. The As-doped a-Si:H film did not crack even after it was heated to a high temperature such as 1000°C. The sheet carrier concentrations were approximately proportional to the square root of the implantation dose. The diffusivity of S can be represented by the equation D
e=D
1 [ K'Q
2/(1 + K'Q
2 )] , where K' is a constant,Q is the implantation dose, and D
1 is the diffusivity of a mobile complex.
Diffusion Barrier Property of Molybdenum Nitride Films for Copper Metallization
Authors: Jeong-Youb Lee Jeong-Youb Lee , Jong-Wan Park Jong-Wan Park
Published: October 2002

Diffusion barrier characteristics of sputtered molybdenum nitride films in copper metallizations for silicon were investigated in terms of interlayer reactions under various conditions of annealing treatments. The Cu/γ-Mo2N/Si structure remained stable upon annealing at 600° C for 30 min, but failure of the diffusion barrier occurred after the heat treatment of 650° C–30 min, when molybdenum silicides and copper silicides were thought to be formed. On heating, the stress of the Cu/γ-Mo2N/Si films decreased due to the agglomeration of the films. Furthermore, interlayer interactions between copper and silicon increased with increasing annealing temperature. These results were investigated by Rutherford backscattering spectrometry, Auger electron spectroscopy, Nomarski microscopy and electrical measurements.
Effect of O2
+ and O+ on the Growth of Bi2Sr2Can-1CunOy Superconducting Films in RF Magnetron Sputtering
Authors: Harada Kanji , Kishida Satoru , Matsuoka Takeru , Maruyama Takafumi , Heizo Tokutaka Heizo Tokutaka , Kikuo Fujimura Kikuo Fujimura
Published: October 2002

We investigated the effect of ionized oxygen molecules ( O2
+) and atoms ( O+) on the film growth of Bi2Sr2Ca

n
-1Cu

n

O

y

(BSCCO). O2
+ and O+ were effectively produced using He+O2 sputtering gas, and O2
+ mainly sputtered the target. The maximum O2
+ content was obtained at a He gas mixture ratio of about 80%, at which BSCCO films with the highest critical temperature (T
c) and a (2223)-phase were obtained. By supplying O2
+ and O+ during the deposition of the films, the superconductivity of the films was improved and the optimum substrate temperature for obtaining the film with the highest T
c in He+O2 sputtering gas became lower than that in Ar+O2 sputtering gas.
Photocurrent and Photoluminescence in InGaAs/GaAs Multiple Quantum Well Solar Cells
Authors: Kitatani Takeshi , Yazawa Yoshiaki , Watahiki Seiji , Tamura Katsumi , Junko Minemura Junko Minemura , Terunori Warabisako Terunori Warabisako
Published: October 2002

We have simultaneously measured photocurrent (PC) and photoluminescence (PL) in GaAs solar cells, including InGaAs/GaAs multiple quantum wells (MQWs) in order to clarify the optimum structure for MQW solar cells. MQW solar cells with shallow wells, for which the carrier escape probability η is calculated to be unity, exhibit a sharp rectifying PC profile. On the other hand, those with deep wells, in which η is nearly zero, exhibit degraded PC-voltage curves and strong PL from the MQWs. From these experimental results, it was found that the introduction of shallow wells with η=1 is essential to prevent degradation of cell performance and is expected to improve the conversion efficiency of MQW solar cells.
Exciton-Related Photoluminescence in 4H-SiC Grown by Step-Controlled Epitaxy
Authors: Itoh Akira , Tsunenobu Kimoto Tsunenobu Kimoto , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

The temperature dependence of exciton-related photoluminescence in 4H-SiC grown by step-controlled epitaxy has been studied in detail. In the low-temperature region, luminescence by recombination of free excitons and excitons bound to neutral nitrogen donors could be observed. From the energy of luminescence peaks by bound excitons, the temperature dependence of the exciton energy gap in 4H-SiC was obtained. The luminescence spectra of free excitons could be explained using a theoretical Maxwellian distribution of the kinetic energy of free excitons, based on a law for indirect-band semiconductors. In thermal quenching properties, the intensity of luminescence by bound excitons decreased with temperature. The quenching energy for luminescence by bound excitons was about 25 meV which was almost coincident with the previously reported binding energy of 20 meV. On the other hand, the intensity of luminescence by free excitons increased to 50 K, and after showing the maximum, it became quenched. From a rate equation analysis using transfer processes among free excitons and bound excitons, the above behavior is explained semiquantitatively.
Realization of Giant Optical Rotatory Power for Red and Infrared Light using III 2VI 3 Compound Semiconductor (GaxIn 1-x) 2Se 3
Authors: Jiping Ye Jiping Ye , Tadashi Yoshida Tadashi Yoshida , Yoshio Nakamura Yoshio Nakamura , Osamu Nittono Osamu Nittono
Published: October 2002

Giant optical rotatory power for red and infrared light is realized along the c-axis using single crystals of the III2VI3 compound semiconductor ( Gax In1-x
)2 Se3 by application of anomalous optical rotatory dispersion occurring at their absorption edges. By changing the composition x within the solid solution range from 0.03 to 0.70, the appropriate band gaps between 1.73 and 2.06 eV are selected and great rotatory power for light with specific wavelength longer than 600–700 nm is obtained. It is found that the greater the proportion of In atoms in the spirally ordered group-III atoms, the greater the optical rotatory power becomes. For single crystal ( Ga0.03 In0.97)2 Se3, a maximum rotatory power of 210°/mm is obtained at λ= 715 nm; the optical rotatory power is always above 90°/mm, being more than 8–15 times that of α-quartz.
Impurity Diffusion in Silicon Based on the Pair Diffusion Model and Decrease in Quasi-Vacancy Formation Energy. Part Two: Arsenic
Authors: Arai Masayuki Yoshida
Published: October 2002

One of the experimental characteristics of As diffusion in Si is that the As diffusion coefficient is independent of its surface concentration but increases approximately linearly with electrically active As concentration. From the viewpoint of the pair diffusion model (PDM), this means that the excess vacancies are not generated and vacancies are in the thermal equilibrium state. Arsenic diffusion is studied on the basis of PDM, taking account of the decrease in quasi-vacancy formation energy. With the decrease in quasi-vacancy formation energy, the binding energy between an As atom and a vacancy also decreases. Fermi level obtained from the Boltzmann statistics is used. Using the literature data for the self-diffusion coefficient of vacancy mechanism and the As diffusion coefficient, the experimental arsenic concentration profile can be well explained.
Below Band-Gap IR Response of Substrate-Free GaAs Solar Cells Using Two-Photon Up-Conversion
Authors: Gibart Pierre , Auzel François , Jean-Claude Guillaume Jean-Claude Guillaume , Khaled Zahraman Khaled Zahraman
Published: October 2002

We have developed a device based upon the concept of two-photon up-conversion to use a part of the IR photons otherwise lost by transparency in a GaAs cell. An ultra thin GaAs cell has been fabricated using the technique of epitaxial lift-off (ELO). This thin cell is placed on top of a 100 µ m thick vitroceramic doped with Yb3+ and Er3+. The two photon upconversion process involved here is based on sequential absorption and energy transfer of two IR photons from Yb3+ to Er3+, which then emit one photon in the green. This green light then produces a photoresponse in the GaAs cell. This cell coupled to the vitroceramic was lighted by an Ti-sapphire IR laser at 1.391 eV, a photon energy below the band gap of GaAs, with an input power able to reach ∼1 W. The GaAs cell photoresponse increases quadratically with the input excitation. For an input excitation of 1 W at 1.39 eV on a 0.039 cm2 substrate-free GaAs cell, the measured efficiency was 2.5%.
Influence of Hydrogen Content and Si-H Bond Structure on Photocreated Dangling Bonds in Hydrogenated Amorphous Silicon Films
Authors: Qing Zhang Qing Zhang , Takayuki Nishino Takayuki Nishino , Hideki Takashima Hideki Takashima , Minoru Kumeda Minoru Kumeda , Tatsuo Shimizu Tatsuo Shimizu
Published: October 2002

Formation and dark annihilation of dangling bonds (DBs) photocreated at 77 K and room temperature have been studied in three types of hydrogenated amorphous silicon (a-Si:H) sample with different hydrogen contents and Si–H bond structures. By comparing the results for the three types of sample, we conclude that the easier photocreation and annihilation of the DBs in the sample with higher hydrogen content are due to the higher flexibility.
Measurement of Temperature Dependence of Dielectric Permittivity of Sapphire Window for High Power Gyrotrons
Authors: Takahashi Koji , Kasugai Atsushi , Sakamoto Keishi , Masaki Tsuneoka Masaki Tsuneoka , Tsuyoshi Imai Tsuyoshi Imai
Published: October 2002

It was measured that the dielectric permittivity of sapphire window changed with temperature rise at the frequencies of 110.0 GHz and 170.0 GHz. The permittivity ε varied from 9.4 to 10.0 at 170.0 GHz with temperature rise from 300 K to 630 K, which can cause a significant rf reflection at the surface of the window and degrade gyrotron oscillation. The permittivity change should be considered for the window design of high power, long pulse gyrotrons and transmission.
Molecular Orientation and Growth Direction of Polydiacetylene Single-Crystal Monolayer at Air-Water Interface
Authors: Shimoyama Susumu Yamada
Published: October 2002

A large single crystal of polydiacetylene monolayer (20×7 mm) was fabricated and the surface structure at the air-water interface analyzed. The surface expansion and unidirectional supply of the film material promoted alignment along the growth direction and crystalline order. Interfacial in-situ microscopy revealed the surface structure of the monolayer to be associated with the facilitated monomer growth and the solid-state polymerization. A novel detection system enabled the observation of polarized fluorescence from the conjugated chain of the polydiacetylene monolayer at the interface. Long-range ordering in the conjugated polymer chains persists along one direction throughout a domain.
Time-Resolved Spectroscopic Measurements of Plasmas after Pulsed Discharges in Liquid Helium
Authors: W. DeSilva Wenhong Qin , Fumihiro Tomimoto Fumihiro Tomimoto , Kuninori Sato Kuninori Sato
Published: October 2002

The densities and electron temperatures in transient plasmas produced by high-voltage pulsed discharges in liquid helium below 4.2 K, at 1 atm, and cryogenic helium gas near 4.2 K, at 1 atm, have been measured by time-resolved emission spectroscopy up to 3.8 µs after the discharges. The densities are measured using Stark broadening of line profiles. The electron temperatures are deduced from the ratios of total spectral line intensities to continuum intensities. Gaseous plasmas with relatively high density and low electron temperature are obtained in cryogenic environments. Typical density and electron temperature at 0.2 µs after breakdown are 1018 cm-3 and 35,000 K, respectively. Mechanisms of the dominant spectral line broadening at an early stage after the discharges in liquid helium are discussed in detail.
Anomaly in Sputtering of Aluminum under N2
+ Ion Bombardment
Authors: Mitsuhashi Riichirou , Hyung-Ik Lee Hyung-Ik Lee , Ryuichi Shimizu Ryuichi Shimizu
Published: October 2002

Sputtering yield measurement of Al for N2
+ ion bombardment with different primary energies has revealed that the sputtering yield at a primary energy of 500 eV is nearly zero, whilst the yields for primary energies greater than 1 keV appear to be similar to those for inert gas ion sputtering which has been described well theoretically and by computer simulations. The sputtering yields are negative for primary energies below several hundred eV at the initial stage of sputtering, which indicates that incident ions are trapped in the specimen and collision cascade results in very little sputtering. Computer simulations for these sputtering processes have also been carried out in order to understand the mechanism of sputtering with reactive ions.
Accelerometer Application of the Modified Moonie (Cymbal) Transducer
Authors: Koc Burhanettin , Dogan Aydin , Fernandez Jose F. , Robert E. Newnham Robert E. Newnham , Kenji Uchino Kenji Uchino
Published: October 2002

The modified Moonie (Cymbal) transducer has been investigated for an accelerometer application. High effective piezoelectric charge coefficients (d
33) of the Cymbal transducer was observed around 15000 pC/N, which is much higher than that of the piezoelectric ceramic itself (∼550 pC/N). With this feature the Cymbal trasducer is a good candidate for high sensitive accelerometer applications. The sensitivity of the Cymbal accelerometer was measured as a function of driving frequency and compared with the single plate ceramic disk which was used as driving component in the transducer. Besides, the geometry of the transducer such as endcap thickness, the effect of different Lead Zirconate Titanate (PZT) compositions and metal endcaps on sensitivity was investigated. The sensitivity 50 times higher than the PZT disk was obtained.
Electrooptic Measurement of Three-Dimensional Nonuniform Electric Field Mapping in Nitrobenzene
Authors: Ihori Haruo , Uto Sadahito , Kiyomitsu Arii Kiyomitsu Arii
Published: October 2002

An electrooptic method is useful for measuring electric fields without disturbing them. Our investigations have been concerned with measurements of electric field distribution. Three-dimensional nonuniform electric field distributions were measured in nitrobenzene using the Kerr electrooptic measurement. The field distributions to be measured were produced in a sphere-to-sphere electrode system. The optical system consisted of a He–Ne laser, a polarizer, a quarter-wave plate, an experimental cell, an analyzer, and a photodetector. When a negative high voltage pulse was applied to the electrode system, the light intensity transmitted to the analyzer was measured using the photodetector. Intensity measurements were carried out at many points from θ= 0 to π around the electrode system. From the data obtained, the electric field distribution, i.e., the strength and direction of each electric field vector in the measured plane, was reconstructed using a computed tomography (CT) technique. The measured distributions were compared with the theoretical ones calculated using an analytical method.
Characterization of Cleaning Technology for Silicon Surfaces by Hot Pure Water Containing Little Dissolved Oxygen
Authors: Hayami Yuka , Suzuki Miki T. , Okui Yoshiko , Hiroki Ogawa Hiroki Ogawa , Shuzo Fujimura Shuzo Fujimura
Published: October 2002

We introduce new cleaning technology using pure water containing little dissolved oxygen (LDO water). To maintain the concentration of dissolved oxygen in water, we performed experiments in a glove box, controlling the ambient between the water and the ambient gas so as to satisfy Henry's law. In the experiment using intentionally contaminated wafers and LDO water containing 1 ppb of dissolved oxygen at room temperature, the amount of residual metallic contaminants, except copper, on a Silicon surface decreased from 1014 atom/cm2 to 1011 atom/cm2 after hot LDO water treatment for 30 min at the boiling point. The cleaning ability depends on the dissolved oxygen concentration, temperature of LDO, and treatment time. The ability to eliminate aluminum during the 30 min hot LDO water treatment was lower than for the other metals. Moreover, the adsorption velocity of aluminum from hot LDO water on the wafer surface was much larger than that of the other metals. Since this hot LDO water treatment simultaneously etched silicon and silicon dioxide with the removal of metal, we also investigated the morphology and chemical structure of the wafer surface after this cleaning process.
Real-Time Ellipsometric Measurement during Growth of (AlXGa1-X)0.52In0.48P Thin Films
Authors: Yoshioka Yoshifumi , Hashimoto Toyoyuki , Yorikazu Shigesada Yorikazu Shigesada , Tamio Yoshida Tamio Yoshida
Published: October 2002

We obtained ellipsometric data during the growth of (Al

X

Ga1-
X

)0.52In0.48P thin films in real time. We have developed a rotating-analyzer ellipsometer and applied it to an MBE system. It is confirmed that ellipsometry is a good system for monitoring thin film quality and that it can be used to determine the composition ratio from the optical constants of (Al

X

Ga1-
X

)0.52In0.48P films grown on GaAs. The thickness and optical constants of a Ga0.52In0.48P/(Al0.4Ga0.6)0.52In0.48P superlattice structure were calculated from ellipsometric data. The average thickness of Ga0.52In0.48P multi-quantum well layers determined by ellipsometry and that determined by photoluminescence showed good agreement. From observation of the surface roughness, it is suggested that a surface roughness of about 6 monolayers was present immediately after the start of growth, and that the surface became planar with time.
Considering the Dependence of the Light-Induced Effect on Carbon Content in Boron-Doped Amorphous Silicon-Carbon
Authors: Isomura Masao , Makoto Tanaka Makoto Tanaka , Shinya Tsuda Shinya Tsuda
Published: October 2002

The inverse Staebler-Wronski effect is observed in boron-doped amorphous silicon (a-Si:H), in which the dark conductivity increases with prolonged light-soaking and recovers with thermal annealing. This effect is suppressed by the incorporation of carbon, and the conventional Staebler-Wronski effect is observed in boron-doped amorphous silicon-carbon (a-SiC:H) with a high carbon content. It is found that the dependence on carbon content is due to the variation of the inverse effect. The inverse effect in a-Si:H shows significant recovery to the initial state even at room temperature, but the conventional effect in a-SiC:H is stable near room temperature. The conventional effect in p-type a-SiC:H is probably similar to that in intrinsic a-Si:H but the inverse effect in p-type a-Si:H has a different mechanism, such as unstable boron activation.
Tunable Near-Infrared and Visible All-Solid-State Optical Parametric Oscillator Amplifier System Based on Potassium Titanyl Phosphate Crystal
Authors: Srinivasan Narayanan , Kimura Takashi , Kiriyama Hiromitsu , Nishida Kanji , Owaki Shigehiro , Yamanaka Masanobu , Izawa Yasukazu , Yamanaka Sadao Nakai
Published: October 2002

We present the design details and performance characteristics of a low-energy all-solid-state near-infrared optical parametric oscillator amplifier (OPOA). The pump source is a laser diode (LD) pumped frequency-doubled Nd:YAG laser with a single mode energy of 4 mJ in 8 ns, 50 Hz pulses. The OPOA system, based on potassium titanyl phosphate (KTP) crystal, features a low pump energy threshold at 532 nm of less than 0.4 mJ, broad tunability from 750 to 1040 nm for the signal and a conversion efficiency of 27% at 920 nm. External cavity second harmonic conversion of the idler to visible green-red light in a type II KTP crystal and of the signal to visible blue-green light in a type I BBO crystal was performed with efficiencies up to 10%. We have used the near-infrared output for wavelength-dependent fluorescence lifetime studies in ytterbium-doped laser materials. We have also used the second harmonic wavelengths between 565–600 nm to measure the transmission of Nd:YAG in a preliminary experiment to demonstrate the utility of the system.
Evaluation of Coupling Coefficients for Laterally-Coupled Distributed Feedback Lasers
Authors: C. Chen Woo-Young Choi , G. Fonstad Clifton
Published: October 2002

Dependence of coupling coefficient, κ, on laterally-coupled distributed feedback (LC-DFB) laser structure is investigated. In LC-DFB lasers, gratings are fabricated on and around the ridge after ridge-waveguide formation and, thus, neither epitaxial regrowth nor growth on corrugated substrates is required. For κ calculation, coupled-mode theory is used with the two-dimensional field intensity calculated using the imaginary-distance beam propagation method. Comparisons are made for LC-DFB lasers with different layer, ridge and grating structures and parameters that affect κ are identified. In addition, it is shown that LC-DFB structure is less sensitive to processing variations and, thus, more manufacturable than a conventional buried heterostructure DFB structure.
State-Space Intercept Method for Seek Control of Optical Disk Drives
Authors: A. Fennema Tetsuo Semba
Published: October 2002

This paper proposes a novel digital seek control method which guarantees a disk drive head moves to the desired trajectory at the next sample. Comparison of the performance with that of a conventional optimal control method by computer simulation showed that this method is more robust to disturbances and unmodeled dynamics, and that the seek time is shorter. This digital control method was implemented on a 5.25-inch MO disk drive of a half-high form factor by using a conventional microprocessor, and it was confirmed that the tracking performance is good and that the average seek time is less than 29 ms.
Phase Change Optical Disks Having Recording Marks with Large Optical Phase Difference Suitable for Mark Edge Recording
Authors: Ide Tatsunori , Syuichi Ohkubo Syuichi Ohkubo , Mitsuya Okada Mitsuya Okada
Published: October 2002

We have developed a novel absorptivity control method for phase change optical disks with the aim of reducing overwriting jitter in mark edge recording without degradation of overwriting cyclability. To control absorptivity more easily, we have designed a disk with a small difference in reflectivity between the amorphous and the crystalline states, and with a large optical phase difference between the reflected light from those two states, which produces a high carrier-to-noise ratio. We have obtained significantly reduced overwriting jitter, down to 2.5 ns for the leading edge, as well as a sufficient overwriting cyclability of up to 105 times.
Hole Mobility in Ge:Ga Far-Infrared Photoconductive Semiconductors at Low Temperatures
Authors: Norihisa Hiromoto Norihisa Hiromoto , Mikio Fujiwara Mikio Fujiwara
Published: October 2002

We have examined drift mobility of holes in Ge:Ga semiconductor crystals with low compensation at low temperature (2–4 K) through the measurement of magnetoresistance. The hole mobility of Ge:Ga with Ga concentration of 2×1014 cm-3 is 5.1–6.6×105 cm2 V-1s-1 at bias field of 1.2 V/cm at 2–4.2 K and that with Ga concentration of 1×1014 cm-3 is larger by a factor of 1.5. The dependence of the hole mobility on temperature is small. These experimental results clearly show that the mobility of holes is mainly determined by neutral-impurity scattering. The dependence of the hole mobility on bias electric field is also small. Ge:Ga crystal uniaxially stressed at about 6×103 kg/cm2 shows larger hole mobility by a factor of 1.5 than the unstressed Ge:Ga when they are compared at nearly zero bias field at 2 K, but they have almost the same value when compared at the bias field of a half of each breakdown field. The hole lifetime of the stressed Ge:Ga, which is derived from the photoconductive gain using the measured hole mobility, is 60 times longer than that of the unstressed Ge:Ga.
Novel Method for Producing Ultrafine Oxide Grains from Metallic Particles
Authors: Suzuki Chihiro Kaito , Noritoshi Tsuda Noritoshi Tsuda , Chiyoe Koike Chiyoe Koike , Yoshio Saito Yoshio Saito
Published: October 2002

Metallic oxide particles have been produced by introducing oxygen gas into a flow of metallic particles. γ-Al2O3, Fe3O4 and Cu2O particles were produced easily by the reaction of metallic particles in a stream of metallic smoke.
Oxide Thin Film Diode Fabricated by Liquid-Phase Method
Authors: Yutaka Ohya Yutaka Ohya , Masayoshi Ueda Masayoshi Ueda , Yasutaka Takahashi Yasutaka Takahashi
Published: October 2002

A p-type oxide thin film, NiO, and an n-type thin film, ZnO, were fabricated by a liquid phase method using metal acetates as starting reagents. Both the films were transparent, uniform in thickness and porous. By repetition of coating of the n- and p-type films a p–n contact was formed. The contact exhibited nonlinear and rectifying I–V characteristics. A Mott-Schottky plot of the p–n contact revealed that the carrier concentration in each film was constant throughout the thickness and the carrier concentration in NiO was much lower than that estimated from the results obtained using the van der Pauw method. The very low carrier concentration may be due to the existence of interface and surface states in the multilayered porous film.
Surface Characterization of Chemically Treated Cu(In, Ga)Se2 Thin Films
Authors: Hashimoto Yasuhiro , Kohara Naoki , Negami Takayuki , Mikihiko Nishitani Mikihiko Nishitani , Takahiro Wada Takahiro Wada
Published: October 2002

The surfaces of Cu-rich and stoichiometric (slightly [In, Ga]-rich) Cu(In, Ga)Se2 (CIGS) thin films were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). At the surface of the Cu-rich and stoichiometric CIGS films, Cu2-
x

Se and Cu(In, Ga)3Se5 exist, respectively. The films were treated using KCN and NH3 aqueous solutions. In the Cu-rich film, the treatment in the KCN solution completely eliminated the Cu2-
x

Se impurity and the treatment in the NH3 solution removed Cu2-
x

Se only at the front surface. In the stoichiometric CIGS film, the NH3 treatment removed Cu(In, Ga)3Se5 from the surface. The recombination of the carriers occurs more in the heterojunction of the CdS/NH3-treated CIGS system than in that of the CdS/as-deposited CIGS system.
Microdegree Azimuth Polarimeter using Optical Heterodyne Detection
Authors: Takahisa Mitsui Takahisa Mitsui , Katsumi Sakurai Katsumi Sakurai
Published: October 2002

We have developed a highly accurate azimuth polarimeter using an optical heterodyne technique with a single-mode laser diode as a light source. Its minimum detectable rotation angle is 0.198 µdeg √ W/Hz ; i.e., it is inversely proportional to the square root of the laser power. Using a glass cell of 1-mm optical path length, we have also successfully observed the optical rotatory power of an aqueous glucose solution whose density is close to that of glucose in human blood.
Evaluation of a Quantum Hall Effect System of Small Size for Use as Resistance Standard
Authors: Masakazu Nakanishi Masakazu Nakanishi , Joji Kinoshita Joji Kinoshita , Toshiaki Sakuraba Toshiaki Sakuraba
Published: October 2002

A quantum Hall effect system (QHE system) of small size has been developed for use as a resistance standard. A QHE sample installed in the system was cooled to about 0.5 K and a magnetic field of up to 9 T was applied to the sample. The system had sufficiently high performance for use as a resistance standard because of the flat plateau (i=4) of the quantized Hall resistance and the wide range of magnetic field for the plateau.
c-Axis Oriented PbTiO 3 Thin Films on MgO and Their Microstructure
Authors: Toshiyuki Mihara Toshiyuki Mihara , Shoichi Mochizuki Shoichi Mochizuki , Ryoji Makabe Ryoji Makabe
Published: October 2002

PbTiO3 thin films were prepared on MgO(100) substrates using a conventional rf magnetron sputtering system with a powder target.
By optimizing the deposition conditions, highly c-axis oriented PbTiO3 epitaxial films were obtained.
The c-axes of the domains in the films were normal to the substrate, but some a-axes were tilted from the normal towards <100> directions with a particular angle and fourfold symmetry.
From the tilt angle and the tilt directions, it is concluded that 90° domain structures were formed by twins, the domain walls of which were {101} twin boundaries.
Time-Dependent Leakage Current Behavior of Integrated Ba0.7Sr0.3TiO3 Thin Film Capacitors during Stressing
Authors: Shimada Yasuhiro , Inoue Atsuo , Nasu Toru , Nagano Yoshihisa , Matsuda Akihiro , Arita Koji , Uemoto Yasuhiro , Eiji Fujii Eiji Fujii , Tatsuo Otsuki Tatsuo Otsuki
Published: October 2002

Time-dependent leakage current behavior of integrated Ba0.7Sr0.3TiO3 capacitors
accelerated by stresses in excess of operating temperature and voltage was studied.
Current-voltage (J-V) studies revealed that the time-dependent leakage current behaviors
are different according to the initial conduction process. When the initial leakage current of
a fully processed integrated capacitor at high voltages at elevated temperatures is of the
Frenkel-Poole emission type, the leakage current increases rapidly with time. The
difference in the initial leakage currents is related to the difference in film growth
conditions which determine the formation of defects in the films. The time-dependent
increase in leakage current is ascribed to a change in the conduction mechanism from the
interface-controlled Schottky type to the bulk-related space-charge-limited type due to the
accumulation of oxygen vacancies near the cathode as a result of interface barrier lowering
and the migration of distributed oxygen vacancies across the film.
Ba2NaNb5O15 Thin Films Prepared by the Pulsed Laser Ablation Method
Authors: Ando Shizutoshi , Nakamura Yoshitaka , Togami Takashi , Okamura Soichiro , Baba Akira , Masuda Youichiro , Takeyo Tsukamoto Takeyo Tsukamoto
Published: October 2002

Ferroelectric thin films of barium sodium niobate, Ba2NaNb5O15
(BNN), were prepared on platinum (Pt) substrates by the pulsed laser
ablation technique using a BNN ceramic target. Crystallographic
properties and the surface morphology of the BNN thin films prepared
were investigated by X-ray diffraction (XRD) and scanning electron
microscopy (SEM). Single-phase BNN thin films were prepared at O2
gas pressure of 1.0×10-1 Torr with marked (00l) plane orientation.
The surface morphology of BNN thin films improved with increasing
O2 gas pressure.
Gas Pressure Dependence of AlN Film Properties in Alternating Sputtering System
Authors: Tominaga Kikuo , Ao Takahiro , Mori Ichiro , Kazuya Kusaka Kazuya Kusaka , Takao Hanabusa Takao Hanabusa
Published: October 2002

AlN films were prepared in N2 and N2/Ar gas by the alternating DC
sputtering method wherein two Al targets facing each other were
sputtered alternately, and the mechanism of film damage in AlN film
preparation was investigated. When the gas pressure was lower than 3 mTorr, the crystalline orientation of the film inclined slightly toward the
direction of incidence of depositing atoms. In this system, the influence
of plasma exposure on the film properties was decreased. This was due to
the decrease of electron flow into the substrate. Degradation of the c-axis
orientation was ascribed to both the tilt of the growth direction of the (00·2) plane at low gas pressures and film bombardment by positive ions
with energies above 60 eV.
Compact Disc Erasable (CD-E) with Ag–In–Sb–Te Phase-Change Recording Material
Authors: Kageyama Yoshiyuki , Iwasaki Hiroko , Makoto Harigaya Makoto Harigaya , Yukio Ide Yukio Ide
Published: October 2002

The compact disc erasable (CD-E) disc has been developed with Ag–In–Sb–Te phase-change recording material. The disc has been designed for recording at a speed twice that of conventional CD's. The CD-E disc has high modulation, high sensitivity, wide power margin after 1000 overwrite cycles and high reliability. It is readable using CD-ROM players and recordable using CD-R recorders with minimum modification.
Construction of Megatorque Hybrid Transducer Type Ultrasonic Motor
Authors: Jun Satonobu Jun Satonobu , Norikazu Torii Norikazu Torii , Kentaro Nakamura Kentaro Nakamura , Sadayuki Ueha Sadayuki Ueha
Published: October 2002

A large hybrid transducer type ultrasonic motor has been studied for the purpose of achieving large output torque.
The goal of our research is to realize a megatorque (i.e., 1000 kgf·cm) ultrasonic motor.
The key to accomplishing this goal lies in obtaining sufficient longitudinal vibration in order to control the frictional force between the rotor and the stator.
In this paper, a motor of 120 mm in diameter using the second longitudinal vibration mode is fabricated and investigated, as a preliminary step toward realization of the megatorque ultrasonic motor.
As a result of our experiments, the maximum torque of 400 kgf·cm was achieved.
Growth of Twinned Lithium Tetraborate Crystal and its Application to Bimorph Actuator
Authors: Komatsu Ryuichi , Iizuka Hiroyuki , Satoshi Uda Satoshi Uda
Published: October 2002

Twinned Li2B4O7 crystals have been successfully grown by the
Czochralski (CZ) method. Parameters necessary for the reproducible
growth of twinned Li2B4O7 crystal have been also investigated. A
piezoelectric bimorph actuator using twinned Li2B4O7 crystal has
been produced. It is confirmed that this actuator shows an excellent
linearity between the applied voltage and displacement.
Digital Optical Deflector Using (Pb, La)(Zr, Ti)O3 Ceramics
Authors: Toshio Utsunomiya Toshio Utsunomiya
Published: October 2002

Optical deflectors are mainly used in the field of optical scanning. Most
optical deflectors utilize the mechanical rotation of mirrors or holograms,
which are suitable for applications such as laser printers. This type of
deflector has two advantages; the deflection angle is large and the
resolution is high. On the other hand, this type of deflector does not
have high-speed response and is not suitable for random access function.
Considering the forthcoming applications of deflectors to optical
communication and optical data processing, the electrooptic deflectors should
be reconsidered. Especially in considering the random access function,
digital optical deflectors are more hopeful than analog ones. One type of
digital optical deflector has already been proposed, which has a discrete
deflection angle due to control of the plane of polarization and the
birefringence of optical crystals. However, this type of deflector is
complex, because it consists of many polarizers and crystals in series.
Aiming at a simpler construction, we propose a new type of digital optical
deflector which consists of an optical divider and a parallel optical shutter
made of (Pb, La)(Zr, Ti)O3 (PLZT) ceramic, and its deflection properties are
investigated theoretically and experimentally.
Nonlinear Optical Study of Phase Transition in Lead Magnesium Niobate
Authors: Fujishiro Kohji , Tazawa Hidehisa , Uesu Yoshiaki , Yamada Yasusada , Yamashita Yohachi
Published: October 2002

The second harmonic (SH) intensity generated in relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 (PMN) was measured using ceramic samples in field-cooling and field-heating after zero-field-cooling processes in the temperature range from 100 to 300 K. Even in the zero-field-cooling process, the SH intensity was observed to increase steeply at about 240 K and saturate near 150 K. This phenomenon can be interpreted by the incoherent summation of the SH amplitude due to scattering by grain boundaries. The behavior also confirms that a polar rhombohedral region develops in the cubic perovskite matrix with decreasing temperature. The non-ergodic behavior was also observed in different cooling/heating paths under an electric field.
Grating Polarizing Beam-Splitter Using Oriented Polydiacetylene Thin Film
Authors: Nakao Satoru , Suzuki Takaaki , Takeda Tadashi , Hayashi Yoshio , Ishikawa Ken , Hideo Takezoe Hideo Takezoe , Atsuo Fukuda Atsuo Fukuda
Published: October 2002

We demonstrated a new type of grating polarizing beam-splitter (GPBS), which is made of an oriented thin film of polydiacetylene (PDA) and has the advantages of light weight and easy fabrication. The extinction ratios of the 2.5-µm-thick element were -8.7 dB and -7.4 dB for the 0th-order and the 1st-order diffraction beams, respectively. The problems that must be solved prior to practical use are discussed.
Possibility of New Mixed Bismuth Layer-Structured Ferroelectrics
Authors: Takenaka Tadashi , Kyo Komura Kyo Komura , Koichiro Sakata Koichiro Sakata
Published: October 2002

Possibilities of new ferroelectrics, Bi5Nb3O15 (BIN) and
Bi5Ta3O15 (BTA), where A=Bi5+, B=Nb5+ and Ta5+ and k=1,
in the general formula of mixed bismuth layer-structured oxides
(MBLSO), Bi4A2
k
-1B2
k
+1O6
k
+9 (k=1, 2, 3, 4), are discussed
using ordinary fired, hot-pressed and hot-forged ceramics. The
lattice constants are a=5.464, b=5.340 and c=21.01 Å for BIN
and a=5.434, b=5.394 and c=20.82 Å for BTA. The D-E
hysteresis loop of hot-pressed BIN at 150° C indicates that BIN
may be a new ferroelectric. The dielectric constant, ε
s, of BTA
shows a peak at about 550° C in the temperature-dependence
curve of ε
s.