bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of Metal-Oxide-Semiconductor Field-Effect-Transistor-Structured Silicon Field Emitters with a Polysilicon Dual Gate
Authors: Kanemaru Seigo , Ozawa Ken , Ehara Keigo , Hirano Takayuki , Hisao Tanoue Hisao Tanoue , Junji Itoh Junji Itoh
Published: October 2002

We have fabricated a new silicon field emitter that incorporates a metal-oxide-silicon field-effect transistor (MOSFET) structure with a dual gate. One gate is an extraction gate that extracts electrons from the emitter. The other is a control gate that controls the channel conductance in order to regulate the emission current. The fabrication process is simple and compatible with conventional LSI process. The present device exhibits excellent controllability and stability of the emission current. This is because electron emission from the emitter is precisely regulated by the channel current of the built-in MOSFET.
Microphotonic Devices Fabricated by Silicon Micromachining Techniques
Authors: Di Fabrizio Enzo , Baciocchi Marco , Gentili Massimo , Grella Luca , Mastrogiacomo Luigi
Published: October 2002

Silicon micromachining is an attractive technique for batch production of a wide class of miniaturised components and systems. In particular, micromachined components can be combined with semiconductor lasers, micro-lenses etc. to develop a class of Microsystems based on photonics (Microphotonics). This class of Microsystems founds applications in modern photonics, such as infra-cavity switches for q-switched lasers, and modulators for free-space optical interconnects. We have designed and fabricated several optical Microsystems based on surface and bulk micromachining techniques. Our process makes use of 100 nm thick Silicon Nitride membranes, which are patterned by electron beam (e-beam) lithography and removed after pattern metallization by reactive ion etching. The first of the fabricated devices is a nickel fine pitch grating driven electrically by the force which develops by the flow currents in two parallel conductors. This force results in a motion which alters the grating pitch and therefore the optical modulation of the device. The second device is a nickel micro-mirror which can be rotated around an axis by the same principle of the previous micro-grating. It is worthwhile to point out that the mirror curvature can be adjusted from convex to concave by controlling the residual stress of the electroplated nickel film; this gives to the optical designer an additional degree of freedom to perform even more sophisticated functions.
Nanometer Pattern-Mask Fabricated by Conventional Photolithography
Authors: Fujimaru Kouji , Ono Takashi , Ryuta Nagai Ryuta Nagai , Hideki Matsumura Hideki Matsumura
Published: October 2002

A novel method to fabricate a nanometer-size pattern-mask by conventional photolithography is proposed. In the method, titanium oxide (TiO2) grown laterally by anodic oxidation at the side-edge of a thin titanium (Ti) layer is utilized to fabricate nanometer-size patterns. The detailed processes and conditions for each process such as anodic oxidation are studied. It is found by scanning electron microscopy (SEM) that the nanometer-size patterns can be fabricated and the size is precisely controlled by the anodic voltage. It is also confirmed by atomic force microscopy (AFM) that a Ti pattern-mask with a slit of a few tens of nanometer width can be fabricated by the present method.
The Mean-Square Relative Displacement and Displacement Correlation Functions in Tetrahedrally and Octahedrally Coordinated ANB8-N Crystals
Authors: Yoshiasa Akira , Koto Kichiro , Maeda Hironobu , Ishii Tadao
Published: October 2002

The Debye-Waller factors of atoms in Ge, GaN, ZnO, CdS, CdSe, CuBr, CuCl, AgI, CdO, AgBr, KBr and RbCl in order of Phillips ionicity (f
i) are studied by both EXAFS and the diffraction method. The displacement correlation functions (DCF) are derived from the mean-square relative displacement (MSRD) and the mean-square displacement (MSD) at room temperature. The magnitudes of the MSRD and MSD correlate well with the coordination number and ionicity. The MSRDs of tetrahedrally coordinated compounds show a gradual approach to those of octahedrally coordinated ones as the ionicity increases. A divergent-like curve toward f
i=0.785 is observed for the MSD in the tetrahedrally coordinated compounds, which indicates the behavior of lattice instability. In the tetrahedrally coordinated covalent materials, the MSRD is nearly half the MSD cation or MSD anion and the ratio of the DCF to MSD given by 2DCF/(MSD cation+MSD anion) is about 80%. In the octahedrally coordinated ionic materials, the MSRD is comparable to the MSD and 2DCF/(MSD cation+MSD anion)=50%. An anharmonic contribution to the Debye-Waller factor determined by EXAFS appears pronouncedly when the magnitude of σ(2) is greater than 0.01 Å2. The MSRD for the tetrahedrally coordinated compounds of silver and copper halides obeys the systematic ionicity dependence and pronounced specificity of anharmonicity was not observed: AgI, CuBr and CuCl of which the high-temperature forms are typical superionic conductors have a broad interatomic potential which is similar to that of the octahedrally coordinated compounds and strongly correlated displacement in thermal vibration between cation and anion.
Formation of a Frozen Nitrogen Target and Characterization for the Application of Pulsed Laser Deposition
Authors: Hiroshima Yasushi , Ishiguro Takashi , Esaki Kotaro
Published: October 2002

ArF and/or KrF excimer laser irradiation on frozen nitrogen, formed on a Nb target using a refrigerator, has been performed. This technique makes it possible to effectively enhance the photo excited reaction between a laser beam and nitrogen because of the high density of nitrogen. The excitation and/or dissociation of nitrogen are examined using a spectroscope and a mass-spectrometer. As a result, the frozen nitrogen was excited via multiphoton processes and emissions of the transitions N2(A
3 Σ
u

+)→ N2(X
1 Σ
g

+), N2(C
3 Π
u
)→ N2(B
3 Π
g
) and N(2
D)→ N(4
S) were observed. Furthermore, it was clarified that both nitrogen molecules and atoms were emitted from the frozen nitrogen effectively by co-ablation with Nb target ablation at a higher laser irradiation energy density.
Optically Detected Cyclotron Resonance by Multichannel Spectroscopy
Authors: Kyoichi Suzuki Kyoichi Suzuki , Ken Saito Ken Saito , Tadashi Saku Tadashi Saku , Yoshiro Hirayama Yoshiro Hirayama
Published: October 2002

We developed a novel setup which includes a multichannel detector for optically detected cyclotron resonance. It can be used to record all photoluminescence (PL) spectra under far-infrared radiation at various magnetic fields. Using this setup, intensity changes can be monitored as a function of the magnetic field simultaneously for all recombination peaks. This system is useful not only for high-sensitivity and high-resolution measurement of cyclotron resonance, but also for studying recombination processes.
Cubic Dominant GaN Growth on (001) GaAs Substrates by Hydride Vapor Phase Epitaxy
Authors: Harutoshi Tsuchiya Harutoshi Tsuchiya , Kenji Sunaba Kenji Sunaba , Syogo Yonemura Takashi Suemasu Syogo Yonemura Takashi Suemasu , Fumio Hasegawa Fumio Hasegawa
Published: October 2002

GaN layers were grown on (001) GaAs substrates by hydride vapor phase epitaxy (HVPE) with buffer layers grown by HVPE under various growth conditions. The ratio of cubic to hexagonal components in the grown GaN layers was estimated from the ratio of the integrated X-ray diffraction intensities of the cubic (002) and hexagonal (1011) planes measured by ω scan. It was found that the cubic/hexagonal ratio greatly depended on the thermal cleaning prior to the buffer layer growth and growth conditions. A thick GaN layer whose cubic component was more than 85% was obtained with thermal cleaning at 600°C for 10 minutes, a ∼ 30 nm buffer layer grown at 500°C and a V/III ratio of 300 during growth at 800°C.
Loss Behaviors of Si Substrate during Growth of the SiC Films Prepared by Hydrogen Plasma Sputtering
Authors: Yong Sun Yong Sun , Tatsuro Miyasato Tatsuro Miyasato
Published: October 2002

Loss behaviors of Si substrates during the growth of β-SiC films, which are grown on the (111) Si substrates kept at 700°C by hydrogen plasma sputtering of the SiC target, are studied by changing the thickness of the obtained films. The Si loss results in hollow voids with a double-deck structure which are observed at the surface of Si substrate. The Si loss roughens the surface of the Si substrate, and influences the properties of the obtained SiC films.
Extremely Transparent and Conductive ZnO:Al Thin Films Prepared by Photo-Assisted Metalorganic Chemical Vapor Deposition (photo-MOCVD) Using AlCl3(6H2O) as New Doping Material
Authors: Myong Seung Yeop , Baik Seung Jae , Lee Chang Hyun , Woo Young Cho Woo Young Cho , Koeng Su Lim Koeng Su Lim
Published: October 2002

Extremely transparent and conductive ZnO:Al thin films were successfully prepared by a photo-assisted metalorganic chemical vapor deposition (photo-MOCVD) technique at a temperature of 140° C using diethylzinc and H2O as source materials. The vapor from an aqueous solution of aluminum chloride hydrate ( AlCl3(6H2O)) was used as a doping gas. ZnO:Al thin films with a minimum resistivity of 6.22×10-4 Ω cm were obtained. Their total transmittance at 550 nm was 91%. Moreover, the average transmittance in the wavelength region of 400 nm to 1200 nm was over 91%. The new Al-doping method using AlCl3(6H2O) by the photo-MOCVD, proposed for the first time in this study, is economical as well as safe, and high-quality ZnO:Al can be successfully applied to a transparent conductive electrode for large area thin-film solar cells.
Interdiffusion between InAs Quantum Dots and GaAs Matrices
Authors: Tetsuya Haga Tetsuya Haga , Mayako Kataoka Mayako Kataoka , Naoki Matsumura Naoki Matsumura , Shunichi Muto Shunichi Muto , Yoshiaki Nakata Yoshiaki Nakata , Naoki Yokoyama Naoki Yokoyama
Published: October 2002

The existence of interdiffusion between self-assembled InAs quantum dots and a GaAs substrate has been investigated using ordinary Rutherford backscattering which is also useful for determining the value of the average InAs layer thickness. As a result, evidence for the diffusion of Ga atoms into the dot is obtained. Furthermore, spatial distribution of the diffused Ga atoms in InAs dots is suggested.
Effect of Crystal Symmetry on Electronic Structures of CuInSe 2 and Related Compounds
Authors: Masakatsu Suzuki Masakatsu Suzuki , Takeshi Uenoyama Takeshi Uenoyama , Takahiro Wada Takahiro Wada , Takeshi Hanada Takeshi Hanada , Yoshio Nakamura Yoshio Nakamura
Published: October 2002

The first-principles band calculations by using the full-potential linearized augmented plane wave method have been used to understand the electronic structures of the chalcopyrite CuInSe2 and the defect stannite CuIn3Se5. It is found that the symmetrized wave function and the d-d mixing as well as the p-d hybridization play important roles in causing the anomalous large band gap of CuIn3Se5. The valence band offset between CuInSe2 and CuIn3Se5 is evaluated to be 0.52 eV. This value is in good agreement with the observed value.
A New Technique of Compound Semiconductor Deposition from an Aqueous Solution by Photochemical Reactions
Authors: Goto Fumitaka , Ichimura Masaya , Eisuke Arai Eisuke Arai
Published: October 2002

CdS films were successfully formed on a glass substrate in an aqueous solution containing S2O3
2- and Cd2+ ions by photochemical reaction. S2O3
2- ions in the growth solution absorb ultra-violet light of wavelengths shorter than about 300 nm, and the excited S2O3
2- ions supply sulfur atoms and electrons to the metal ions such as Cd2+. Thus, the formation reaction of the sulfide semiconductor occurs in the only illuminated region. Photochemically deposited CdS thin films were polycrystalline of hexagonal structure. The composition of the films became stoichiometric by the annealing at temperatures higher than 300° C.
Impact of Gate Microstructure on Complementary Metal-Oxide-Semiconductor Transistor Performance
Authors: Yu Bin , Ju Dong-Hyuk , Kepler Nick , Tsu-Jae King Tsu-Jae King , Chenming Hu Chenming Hu
Published: October 2002

This letter reports on the impact of gate microstructure on deep-submicron complementary metal-oxide-semiconductor (CMOS) device performance. Transistors with different gate microstructures (α-Si gate vs poly-Si gate) were fabricated using a 2.5 V sub-0.25 µ m CMOS process and their performances were compared. The α-Si gate provides better capability for suppressing boron penetration in p-channel metal-oxide-semiconductor field-effect transistors (MOSFET's), but the depletion effect is more severe than that of the poly-Si gate. A modified gate doping (MGD) effect, in which the difference of linear transconductance (g
m) between transistors with two different gate microstructures shows a strong gate-length dependence, is reported for the first time and evaluated by the impact of grain boundary segregation on the electrically activated gate impurity density. The MGD effect makes the poly-Si gate more advantageous in the design of high-performance CMOS transistors with gate critical lengths shorter than 0.25 µ m.
Study of the Initial Growth Process of ZnSe on Si(111) by Molecular Beam Epitaxy
Authors: Méndez-García Victor Hugo , Máximo López-López Máximo López-López , Isaac Hernández-Calderón Isaac Hernández-Calderón
Published: October 2002

Reflection high-energy electron diffraction, atomic force microscopy, and Auger spectroscopy were used to study the initial stages of growth of ZnSe on Si(111) substrates by molecular beam epitaxy. Initially, ZnSe grows in a three dimensional mode: after 7 monolayers (ML) of depositon the islands height is ∼20 Å, with a diameter of ∼650 Å, and a density of ∼20 islands per µ m2. Around ∼10 ML of deposition the growth changes to a two dimensional mode, and finally, a flat ZnSe surface is obtained for ∼30 ML. The island formation at the initial stage of growth could be used to synthesize self assembling ZnSe-quantum dots. On the other hand, the fast change to a two dimensional growth mode is very useful for structures requiring a flat surface.
Temperature Dependence of Emission Cross-section of Yb:glass
Authors: Kiriyama Hiromitsu , Srinivasan Narayanan , Yamanaka Masanobu , Izawa Yasukazu , Tatsuhiko Yamanaka Tatsuhiko Yamanaka , Sadao Nakai Sadao Nakai
Published: October 2002

The temperature dependence of the emission cross-section of Yb (5 ×1020 atoms/cm3)-doped fluorophosphate glass has been investigated in the temperature range from 77 K to 380 K. The emission cross-section has been evaluated from the measured fluorescence spectra and the lifetime, using the Füchtbauer-Ladenburg formula. A large change in the emission cross-section from about 0.6×10-20 cm2 at 380 K to 1.1×10-20 cm2 at 77 K was obtained by decreasing the temperature. The effect of reabsorption is found to be significant even at temperatures as low as 160 K which leads to underestimation of the emission cross-section values.
Mapping of Vanadium-Related Luminescence on SiC Wafer at Room Temperature
Authors: Tajima Michio , Kumagaya Yoshikazu , Nakata Toshitake , Inoue Morio , Nakamura Akira
Published: October 2002

The intensity distribution of vanadium-related luminescence is investigated on a 4H SiC wafer. Two-dimensional mapping of the vanadium-related line on the sample at room temperature agrees with the defect image obtained by optical microscopy: the luminescence intensity becomes high around the cracks. The intensity profile measurement at 4.2 K indicates that not only the vanadium-related line but the donor-acceptor pair emission increases the intensity around the crack. This result leads us to suggest that microdefects acting as killer centers for minority carriers are gettered by the cracks, resulting in the formation of a denuded zone around them.
Formation of Piled Circular Texture Induced by Alternating Electric Field in Freely Suspended Ferroelectric Liquid Crystal Films
Authors: Tazoh Sadahito Uto , Masanori Ozaki Masanori Ozaki , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Unique piled circular textures induced by an alternating electric field have been observed in a freely suspended ferroelectric liquid crystal film using a polarizing microscope. Molecular alignments in the textures are clarified and the formation process of the texture is discussed.
Conducting Polymer Color Sensor
Authors: Kazuya Tada Kazuya Tada , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

A color sensor device using conducting polymer poly(3-hexylthiophene) (PAT6), has been fabricated and characterized. The device consists of two photocells made of the same conducting polymer with different polymer thicknesses, and which exploits the difference in the photocurrent spectrum of the photocells. The color of the irradiated light can be detected by measuring the ratio of the short-circuit photocurrent of two photocells with different PAT6 thicknesses. The color sensor proposed here is suitable for large-area sensor systems such as the integrated image sensor device because of its simple structure.
Proof of Principle Experiments for Compton Scattering of a Stored Photon in a Supercavity
Authors: Moon Ahsa , Fujita Masayuki , Yasuda Eiji , Tanaka Hidehiro , Roy Prabir Kumar , Daicho Masato , Ohkubo Koichi , Nakao Naoya , Watanabe Takeshi , Ishida Takayuki , Imasaki Kazuo , Ohigashi Nobuhisa , Tsunawaki Yoshiaki , Mima Kunioki , Yamanaka Sadao Nakai
Published: October 2002

We observed that Compton-scattered photons are enhanced in a supercavity. We can increase the laser beam intensity in such a cavity and obtain a reasonable number of scattered photons. In our experiments, an e-beam of ∼82 keV and a 1 µ m wavelength laser beam were used in the supercavity. The storage rate of the supercavity was ∼4000 times. The wavelength of the scattered photons was calculated to be 364 nm and the flux to be approximately 400 [photons/s]. The experimental results agree well with the theoretical prediction.
The Sb2O3 Addition Effect on Sintering ZnO and ZnO+Bi2O3
Authors: Ito Masahiro , Tanahashi Masakazu , Uehara Miho , Iga Atsushi
Published: October 2002

The effects of adding minute quantities of Sb2O3 when sintering ZnO and ZnO+Bi2O3 (0.5 mol%) were studied. To prevent non-uniform distribution of the additive, dilute solutions of Sb-salts were used instead of solid Sb2O3. Very small quantity additions of Sb2O3 retarded sintering of both ZnO and ZnO+Bi2O3 (0.5 mol%). The sintering retarding effect, however, is lost when a powder mixture composed of Bi2O3+Sb2O3 is heat-treated to have these additives reacted with each other before they are added to the ZnO matrix.
Temperature Dependence of the Spin Tunneling Magnetoresistive Effect on NiFe/Co/Al2O3/Co/NiFe/FeMn Junctions
Authors: Kumagai Seiji , Nobuki Tezuka Nobuki Tezuka , Terunobu Miyazaki Terunobu Miyazaki
Published: October 2002

Spin-valve type spin tunneling junctions using contact metal masks have been fabricated. The annealing effect and temperature dependence of the tunneling magnetoresistance (TMR) ratio and saturated resistance (R
s) have been investigated. As-prepared NiFe/Co/Al2O3/Co/NiFe/FeMn junctions show a spin-valve like MR curve and a TMR ratio of up to 28% at room temperature. The temperature dependence of the TMR ratio and R
s is affected by the annealing. For annealed junction, the TMR ratio slightly decreases with increasing temperature and rapidly decreases around 418 K because of the disappearance of an exchange bias of the FeMn layer.
Flatness Improvement of GaAs Observed by Atomic Force Microscopy Using Flow Rate Modulation Epitaxy
Authors: Ming-Kwei Lee Ming-Kwei Lee , C. C. Hu C. C. Hu
Published: October 2002

From atomic force microscope observation, the flatness of a GaAs homoepitaxial layer is improved on an atomic scale by arsine modulation metalorganic chemical vapor deposition. Furthermore, a full width at half-maximum of 6.4 meV for photoluminescence at 77 K can be obtained under optimum growth conditions. The amplitude of the satellite peak around the near band emission can also be reduced significantly. The satellite peak is associated with arsenic related antisite defects.
Mesogenic Polymer Stabilized Ferroelectric Liquid Crystal Display Exhibiting Monostability with High Contrast Ratio and Grayscale Capability.
Authors: Hirokazu Furue Hirokazu Furue , Tomohiro Miyama Tomohiro Miyama , Yasufumi Iimura Yasufumi Iimura , Hiroshi Hasebe Hiroshi Hasebe , Haruyoshi Takatsu Haruyoshi Takatsu , Shunsuke Kobayashi Shunsuke Kobayashi
Published: October 2002

We have fabricated a new ferroelectric liquid crystal (FLC) display that exhibits monostable electrooptical characteristics with high contrast ratio (160:1) owing to freedom from defects, grayscale capability without threshold, and fast response (70 µs). A FLC(ZLI-4654-100, Merck) is subjected to polymer stabilization by UV photocure of a mixture of doped monoacrylates with a mesogenic side chain particularly at a temperature where the LC medium is in the SmC* phase under the simultaneous application of a monopolar electric field.
A Theoretical Investigation of Stable Lattice Sites for In Adatoms on GaAs(001)- (2×4) Surface
Authors: Shiraishi Tomonori Ito
Published: October 2002

Stable lattice sites of In adatoms on the GaAs(001)-(2×4)β2 surface are qualitatively investigated using empirical interatomic potential and an energy term as a function of the number of electrons remaining in the cation dangling bonds. The calculated results imply that the lattice sites in the missing dimer row are favorable for In adatoms on the GaAs(001)-(2×4)β2 surface, since the formation of Ga-In dimers suppresses the number of electrons remaining in the cation dangling bonds. Lattice sites in the missing dimer row near the B-type step edge are stable for an In adatom. This creates Schwoebel barriers at the B-type step edge. However, no preferential adsorption sites are found near A-type step edges. These results are comparable with the results on Ga adatoms we obtained in our previous study.
Formation of Sb Nanocrystals in SiO2 Film Using Ion Implantation Followed by Thermal Annealing
Authors: Nakajima Anri , Futatsugi Toshiro , Naoto Horiguchi Naoto Horiguchi , Naoki Yokoyama Naoki Yokoyama
Published: October 2002

In this letter we report on the fabrication of Sb nanocrystals in SiO2 film, for the first time. These nanocrystals were fabricated by ion implantation followed by thermal annealing. We confirmed their formation in SiO2 via transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis. The size and depth of nanocrystals in film can be controlled by changing the implantation dose and energy. This fabrication method is completely compatible with large-scale integrated (LSI) device fabrication. Thus, it opens up the feasibility of using metal nanocrystals for creating new devices such as high-temperature single-electron devices.
Design, Fabrication and Evaluation of a Four-Josephson-Junction Superconducting Quantum Interference Device with Two Superconducting Loops
Authors: Toshimitsu Morooka Toshimitsu Morooka
Published: October 2002

We developed a four-Josephson-junction superconducting quantum interference device (4JJ-SQUID) with a large modulated voltage to realize a highly sensitive magnetic sensor. This letter describes the design and fabrication, and discusses the potential and the performance of the 4JJ-SQUID. The 4JJ-SQUID was fabricated using Nb/Al–AlO

x

/Nb tunnel junctions. The SQUID consists of two pairs of Josephson junctions that form two superconducting loops via a shared washer coil. We confirmed using both calculation and experiment that the SQUID had a higher magnetic sensitivity than that of a conventional DC-SQUID.
Digital Thermooptic Switch Formed Using Silicone Resin Waveguides
Authors: Ooba Toshio Watanabe , Hida Yasuhiro , Hayashida Shoichi , Takashi Kurihara Takashi Kurihara , Saburo Imamura Saburo Imamura
Published: October 2002

Polymer waveguides made with deuterated silicone resin have a low propagation loss of 0.5 dB/cm at 1.55 µ m, and offer long term stability in the humid conditions of 90% RH at 75° C. A digital thermooptic switch formed using the silicone resin waveguides exhibits an insertion loss of <2.5 dB, an extinction ratio of >30 dB at 1.55 µ m. This switch is insensitive to wavelengths in the range of 1535–1620 nm, and operates properly even at 80° C.
Deposition of High-Quality Silicon Oxynitride Film at Low Temperature by Using a Sputtering-Type Electron Cyclotron Resonance Plasma
Authors: Gao Da-Wei , Kashiwazaki Yasuhiro , Muraoka Katsunori , Nakashima Hiroshi , Furukawa Katsuhiko , Liu Yi-Chun , Tsurushima Toshio
Published: October 2002

Si oxynitride dielectric films having good electrical and structural characteristics were deposited at 130° C by a sputtering technique using an electron cyclotron resonance plasma. This was demonstrated by studying breakdown characteristics, chemical etch rate, refractive index, and chemical bonding characteristics as a function of the flow rate ratio of O2 to N2. At the optimum condition, the oxynitride films had refractive indexes in the range 1.5–1.6 and infra-red peak positions in the range 955–1035 cm-1, and showed a high breakdown field of 12–13 MV/cm. It was found that the breakdown field and charge trapping of the oxynitride films were superior to those of thermally grown oxide. These improvements are interpreted as being due to a suitable N-atom incorporation into the films during the deposition process, enabling the formation of a partial O–Si–N amorphous network.
Effect of Hydrogenation on ZnO Luminescence
Authors: Takashi Sekiguchi Takashi Sekiguchi , Naoki Ohashi Naoki Ohashi , Yoshihiro Terada Yoshihiro Terada
Published: October 2002

The effect of hydrogenation on the luminescence property of ZnO crystal was investigated by means of cathodoluminescence (CL). It was found that hydrogen plasma treatment strongly passivates the green emission and enhances the band edge luminescence. The band edge luminescence of ZnO crystals in the as-grown state does not show any significant temperature dependence. However, that of hydrogenated ZnO crystals shows strong temperature dependence and the intensity increases significantly at low temperatures. At 30 K, the number of luminescent photons exceeds several tenths of generated electron-hole pairs.
Dynamics of Phasons; Phase Defects Formed on Dimer Rows, and Related Structural Changes of the Si(100) Surface at 80 K Studied by Scanning Tunneling Microscopy
Authors: Shigekawa Hidemi , Miyake Koji , Masahiko Ishida Masahiko Ishida , Kenji Hata Kenji Hata
Published: October 2002

Type-P defects, which are mobile phase defects on dimer rows with a structure similar to that of the type-C defect, were observed on Si(100) surface at 80 K, however, the observed surface structure was mainly c(4×2), contrary to the previous results obtained at 6 K. Complete p(2×2) arrangement was unstable, and type-P defects tended to form pairs with other type-P defects on neighboring dimer rows, resulting in a reduction of the area with complete p(2×2) arrangement. This is the first observation of the interacting phasons; type-P defects formed on Si(100) surface. The observed results were analyzed with the Ising model, and domain boundaries between c(4×2) and p(2×2) arrangements were found to play an important role in the dynamics of type-P defects at 80 K.
Structural Change of As-Stabilized GaAs(001)-( 2×4) and -c( 4×4) Induced by Zinc Exposure
Authors: Miwa Shiro , Kuo Li Hsin , Kimura Kozo , Yasuda Tetsuji , Yao Takafumi
Published: October 2002

The surface structures of Zinc-treated As-stabilized GaAs(001)-(2×4) and -c(4×4) have been studied using reflection high-energy electron diffraction, in situ scanning tunneling microscopy and transmission electron microscopy in order to understand the Zn-pre-exposure process in ZnSe growth on GaAs(001) . A weakening of RHEED patterns of [110] azimuth was observed in Zn-exposed GaAs-(2×4) surface. However, no obvious change was shown in STM images. On the other hand, Zn-exposure on a GaAs-c(4×4) surface induced a (2×2) or very weak (1×4) surface structure in RHEED patterns. Protrusions and an As-dimers/missing-dimer structure were seen in STM images. Moreover, during ZnSe growth the surface protrusions observed by STM can diffuse into the film and produce As precipitates that are confirmed by TEM.
Effect of the Field Dependent Permittivity and Interfacial Layer on Ba1-xKxBiO3/Nb-Doped SrTiO3 Schottky Junctions
Authors: Yamamoto Tetsuya , Suzuki Seiji , Suzuki Hiroshi , Kawaguchi Kenichi , Kazuhiko Takahashi Kazuhiko Takahashi , Yorinobu Yoshisato Yorinobu Yoshisato
Published: October 2002

The electrical properties of Ba1-
x

K

x

BiO3/Nb-doped SrTiO3 all-oxide-type Schottky junctions have been investigated by measuring their current-voltage and capacitance-voltage ( C-V ) characteristics at room temperature. The relative permittivity ε
r of Nb-doped SrTiO3 could be approximated as ε
r(E)=b/√ a+E
2, where E is the electric field, a and b are constants. Taking into account the field dependent permittivity and interfacial layer, we carried out a quantitative analysis of the potential barrier and 1/C
2-V characteristics. The non-linear 1/C
2-V characteristics could be quantitatively explained by considering the field dependent permittivity and the bias dependence of the barrier height due to the presence of the interfacial layer.
Formation of an Atomically Flat Surface of ZnSe on GaAs (001) by Metalorganic Vapor Phase Epitaxy
Authors: Funato Mitsuru , Aoki Satoshi , Shizuo Fujita Shizuo Fujita , Shigeo Fujita Shigeo Fujita
Published: October 2002

Surface morphologies of pseudomorphic ZnSe on GaAs (001) grown by metalorganic vapor phase epitaxy have been studied by atomic force microscopy. The observation of ZnSe grown at 400, 450 and 500°C reveals that the growth mode below 450°C is 2 dimensional (2D), while that at 500°C is highly 3D. In particular, growth at 450°C is in the layer-by-layer mode. These observations are interpreted in terms of temperature-enhanced migration of Zn adatoms and evaporation of Se from the ZnSe surface. An atomically flat ZnSe surface which consists of wide terraces without small 2D islands can be obtained by growing at 450°C and post-growth annealing at the same temperature in Se ambient.
95 K NdBCO Single Crystal Grown in Air by Controlling Liquid Composition
Authors: Yao Xin , Kambara Makoto , Umeda Takateru , Yuh Shiohara Yuh Shiohara
Published: October 2002

Using the crystal pulling method, we achieved high superconducting transition temperatures (T
c) of Nd1+
x

Ba2-
x

Cu3O6+δ (NdBCO) single crystals in air. By controlling the liquid composition of the ratio of Ba to Cu (Ba/Cu) at approximately 0.80, the NdBCO crystal displays high T
c of about 95 K with a sharp transition width ΔT of less than 0.5 K. The high Ba/Cu in the liquid leads to the low amount of substitution of Nd for Ba, and consequently results in high superconducting properties. This finding suggests that the Ba/Cu in the liquid is a very important processing parameter for the NdBCO system.
Nonlinear Emission from 8-Hydroxyquinoline Aluminum and Diamine Derivative Superlattice Structures Excited by Third-Harmonic-Generation from Nd:YAG Laser Light
Authors: Norio Tada Norio Tada , Satoshi Tatsuhara Satoshi Tatsuhara , Akihiko Fujii Akihiko Fujii , Yutaka Ohmori Yutaka Ohmori , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Photoluminescence from organic superlattice structures with 8-hydroxyquinoline aluminum (Alq3) and aromatic diamine (TPD) has been studied in terms of the excitation power density of third-harmonic-generation (THG) light from a Nd:YAG laser and the layer thickness of superlattice structures. The photoluminescence intensity from the Alq3 layer is enhanced with decreasing layer thickness of TPD in a superlattice structure independent of the excitation power density. With increasing excitation power density, the photoluminescence intensity from the TPD layer is enhanced compared with that from Alq3. The mechanism of nonlinear photoluminescence emission from Alq3 and TPD superlattice structures is discussed, taking the energy transfer and the interaction of excitons in the superlattice structure into consideration.
Growth of Polar NaCl(111) Surface on GaAs(111) Substrates
Authors: Saiki Koichiro , Akira Goda Akira Goda , Atsushi Koma Atsushi Koma
Published: October 2002

Growth of a polar NaCl(111) surface on GaAs(111) substrates has been examined using molecular beam epitaxy (MBE). NaCl film grown on a complex heterostructure of CuCl/CuBr/GaAs(111)Ga 2×2 shows a streaky RHEED pattern indicative of a rather flat (111) 1×1 surface. Electron energy loss (EEL) spectra of this surface suggest the existence of lower energy excitations on the top surface, in contrast to the normal (100) surface characterized by a large band gap. This result is expected to prompt investigation of anomalous surface properties of (111) alkali halide faces.
Anomalous High Rate Reactive Ion Etching Process for Indium Tin Oxide
Authors: Yue Kuo Yue Kuo
Published: October 2002

An anomalous high indium tin oxide etch rate, i.e., 1630 Å/min, reactive ion etching condition has been obtained. This process is based on the combination of high temperature, i.e., 250° C, and a mixture of HCl and CH4 gases. Throughout the whole range of the gas composition, the highest etch rate is obtainable in a small CH4 concentration range, e.g., around 40%. The same phenomenon has been observed at different plasma powers. The influence of temperature or power to the etch rate is not obvious unless a threshold temperature or a threshold power is surpassed. The pure HCl plasma etched surface is in liquid form and has a rough topography after solidification. The HCl/40% CH4 etched surface is solid and has a smooth topography. A high etch rate is contributed by near-stoichiometric surface reactions as well as strong ion bombardment.
X-Ray Photoelectron Spectroscopy Study of Native Oxidation on Misoriented Si(100)
Authors: Yano Fumiko , Toshihiko Itoga Toshihiko Itoga , Keiichi Kanehori Keiichi Kanehori
Published: October 2002

Native oxidation on Si(100) misoriented by about 4 degrees toward [011], which is often used as a substrate for ULSI fabrications, is investigated. On the exactly oriented wafer, the relationship between the oxide thickness and the exposure time in a clean-room atmosphere showed that layer-by-layer oxidation clearly took place. However, the oxidation on the misoriented wafer followed a more linear pattern. We found that the oxidation on the misoriented wafer can be explained by quasi-one-dimensional oxidation model, where the oxidation is limited to the terrace width and spreads only in the direction along the terrace. Simulated oxide thicknesses based on this model agreed well with our XPS results.
In Situ Measurement of Adhesion Force between a Single Microparticle and a Surface Using Radiation Pressure of Pulsed Laser Light
Authors: Sasaki Keiji , Horio Koji , Masuhara Hiroshi
Published: October 2002

A new method is proposed for analyzing the adhesion force between a single microparticle and a solid surface in air. The method is based on the µ N radiation force that is exerted on a particle by nanosecond pulsed laser light, which pulls a particle from a transparent solid surface against the adhesion force. The strength of the force is determined on the basis of the Mie scattering theory with the critical laser intensity at which the radiation pressure and the adhesion force are balanced. This optical force measurement has the advantages of no mechanical contact, of applicability to micro∼nanometer-sized particles and of causing no perturbations on the physical and chemical conditions of a sample. The high potential of this method is clearly demonstrated in the analysis of the adhesion force between polymer latexes and glass surfaces.
Growth of InN at High Temperature by Halide Vapor Phase Epitaxy
Authors: Takahashi Naoyuki , Matsumoto Ryu , Akinori Koukitu Akinori Koukitu , Hisashi Seki Hisashi Seki
Published: October 2002

Epitaxial growth of InN at high temperature was tried on a GaN buffer/(0001)sapphire substrate by halide vapor phase epitaxy using InCl3 and NH3 sources. An InN epitaxial layer was obtained reproducibly at a growth temperature as high as 750° C. The growth rate of hexagonal InN was 0.2 µ m/h at 750° C. The X-ray full width at half-maximum (FWHM) value of the obtained InN showed a minimum (24.7 min) at the growth temperature of 700° C. It was found that a high input partial pressure of InCl3 was necessary for the growth of InN at high temperature.
Photoluminescence and Photothermal Deflection Spectroscopy of InAs Quantum Dot Superlattices Grown on GaAs by Molecular Beam Epitaxy
Authors: Dai Yuan-Tung , Liu Ying-Tsang , Lin Ray-Ming , Liao Ming-Chih Harris , Chen Yang-Fang , Lee Si-Chen , Lin Hao-Hsiung
Published: October 2002

In this report, we apply simultaneously the measurements of luminescence and absorption to InAs/GaAs quantum dot superlattices grown on GaAs substrates. It is found that the peak energy obtained by a radiative process increases with decreasing dot size due to the effect of quantum confinement. Because the size of the quantum dots that we studied is significantly larger than that of dots in previous reports, we are able to justify the theoretical calculation of the transition energy in InAs dots grown by molecular beam epitaxy. A highly sensitive technique of photothermal deflection spectroscopy (PDS) is used as the absorption technique. We show that PDS is more than sufficient to measure optical absorption in thicknesses of a few atomic layers. The obtained band-gap energies for different sizes of InAs quantum dots can be predicted accurately by the quantum confinement effect and agree well with the results of photoluminescence measurements. We demonstrated that PDS is an alternative tool for the study of nano-structure devices.
LiNbO3 Wavelength Router Using Bridged Planar Spectrographs
Authors: Okayama Hideaki , Okabe Yutaka , Toru Arai Toru Arai , Takeshi Kamijoh Takeshi Kamijoh
Published: October 2002

We propose a wavelength router composed of a pair of connected planar spectrographs to attain multiple input and output ports. The equal-length waveguide array connecting the two planar waveguides is used to relax fabrication tolerance. The crosstalk below -20 dB and filter bandwidth of 5 nm were attained with a device fabricated in LiNbO3.
Structural Study of the Si(111)(√ 3×√ 3)R30°–Au Surface Using One-Beam Reflection High Energy Electron Diffraction Intensity Rocking Curve Analysis
Authors: Khramtsova Elena A. , Ayahiko Ichimiya Ayahiko Ichimiya
Published: October 2002

The structure of the Si(111)(√3×√3)R30°–Au surface has been investigated using rocking curves of reflection high energy electron diffraction at one-beam condition. It has been found that frequently this surface forms through formation of the metastable Si(111)(2√21×2√21)R10.9°–Au structure, which transforms gradually and irreversibly into the √3×√3–Au one. One-beam rocking curves for all proposed models of the √3×√3–Au surface have been calculated and compared with the experimental one. A conjugate honeycomb-chained-trimer model proposed by Ding et al. [Surf. Sci. 275 (1992) L691] has been found to be the only one that fits the experimental data satisfactorily. The calculation result can be fitted to the experimental one by introduction of additional density of Au and Si atoms which are assumed to be incorporated into domain walls. Thereby, interlayer distances and atomic densities of surface parallel layers have been determined and atomic densities corresponding to the domain walls and commensurate phase regions have been separated.
Combination of Photo and Atomic Force Microscope Lithographies by Use of an Organosilane Monolayer Resist
Authors: Hiroyuki Sugimura Hiroyuki Sugimura , Nobuyuki Nakagiri Nobuyuki Nakagiri
Published: October 2002

Two lithographies having different resolutions of micro and nanometer scales have been combined using a single organosilane monolayer as a resist for both. This monolayer resist was first patterned by irradiation with deep ultraviolet light through a photomask. Prior to the second patterning by scanning probe lithography, the photopatterned monolayer was observed by an atomic force microscope (AFM) in lateral force microscopy (LFM) mode. Since the photodegraded monolayer showed stronger lateral force than the unirradiated monolayer, the photogenerated pattern on the monolayer was clearly imaged. Using this LFM image, the AFM probe was aligned on the photofabricated pattern before drawing additional patterns by scanning probe lithography.
Effect of Foreign Gas on ν3-Mode Vibrational Temperature for Regular and Sequence Band Transitions in Waveguide CO2 Lasers
Authors: Shimizu Fumiko O. , Kawai Kenji , Homma Hiroyuki , Minoh Arimichi
Published: October 2002

From small signal gain measurements for the CO2 regular and sequence band transitions in a waveguide laser medium, the foreign gas effect on the ν3-mode vibrational temperature is investigated and compared with that in a large-bore flow tube, ordinary laser medium. The vibrational temperature in the waveguide is apparently higher than that in a large-bore flow tube, ordinary laser at any partial pressure of foreign gas in the gas mixture. The vibrational temperature decreases with increasing foreign gas N2 partial pressure, whereas it increases with increasing He partial pressure. The total and partial derivatives of the vibrational temperature for the variables of the foreign gas pressure and the injected power are experimentally obtained and discussed.
A 0.7-µm-Pitch Double Level Al Interconnection Technology for 1-Gbit DRAMs using SiO2 Mask Al Etching and Plasma Enhanced Chemical Vapor Deposition SiOF
Authors: Yokoyama Takashi , Yamada Yoshiaki , Kishimoto Koji , Usami Tatsuya , Kawamoto Hideaki , Ueno Kazuyoshi , Gomi Hideki
Published: October 2002

A 0.7-µm-pitch double level aluminum (Al) interconnection technology on a 1-µm-high step is established for 1-Gbit dynamic random access memories (DRAMs). A SiO2 film which has a high resistance to Al etching was used as the mask layer. 0.35-µm-width Al wirings were fabricated even on a 1-µm-high step. 0.2-µm-spaces (aspect ratio=2.5) between the taper shaped Al lines were filled, for the first time, by a plasma enhanced chemical vapor deposition (PECVD) fluorine doped silicon oxide (SiOF) film (ε=3.9). The SiOF film capped with the PECVD SiO2 film has enough stability for the process integration. It was confirmed that these technologies can be applied to a double level Al interconnection using a 0.3-µm-diameter tungsten (W) plug.
Effect of Thin-Film Texture and Zirconium Diffusion on Reliability against Electromigration in Chemical-Vapor-Deposited Copper Interconnects
Authors: Awaya Nobuyoshi , Kobayashi Toshio
Published: October 2002

The effects of film texture and zirconium diffusion on the reliability of chemical-vapor-deposited (CVD) copper interconnects were examined. The crystallographic orientation of CVD copper depends strongly on the substrate structure and pre-treatment sequences. Sputter pre-etching of TiN liner greatly enhanced the (111) orientation of sputter deposited copper film. The CVD copper grew epitaxially on the (111) oriented sputtered copper seed layer. Dominant impurities in CVD copper are oxygen and fluorine, which can be reduced by hydrogen annealing at 400°C. By improving the texture, the lifetime against electromigration extends about twice longer than that of as-deposited CVD copper film. Copper zirconium alloy wire with a surface layer of the inter-metallic compound CuZr2 further extended the electromigration lifetime due to thermal diffusion of zirconium into copper. The electromigration lifetime of this alloy wire was significantly improved with only a small increase in electrical resistivity.
Minimization of BF2
+-Implantation Dose to Reduce the Annealing Time for Ultra-Shallow Source/Drain Junction Formation below 600°C
Authors: Kanemoto Kei , Nakada Akira , Ohmi Tadahiro
Published: October 2002

Fluorine remaining in the BF2
+ implanted layer causes the problem of long annealing time at low temperatures. We investigated the effect of the reduction in the BF2
+ dose on the annealing time at 510°C and 465°C by the measurements of the sheet resistance, carrier profile, and by the observation of the crystallinity. The dependence of the junction leakage current on the dose was also investigated. A 25% reduction in the annealing time at 510°C was obtained by reducing the dose from 2×1015 cm-2 to 8×1014 cm-2, keeping a high carrier concentration of about 1×1020 cm-3 in the p+ layer, which has a junction depth as shallow as 40 nm. For the junction leakage current, no apparent degradation was observed. At 465°C, the annealing time was reduced by as much as 8 h by reducing the dose from 2×1015 cm-2 to 8×1014 cm-2. Minimizing the BF2
+ dose is essential in the formation of ultra-shallow junctions at low temperatures in a short annealing time.
Gas Chemistry Dependence of Si Surface Reactions in a Fluorocarbon Plasma during Contact Hole Etching
Authors: Komeda Hiroyuki , Ueda Tohru , Wada Sakae , Ohmi Tadahiro
Published: October 2002

Gas chemistry dependence of Si surface reactions in a high C/F ratio fluorocarbon plasma during contact hole etching was investigated. CO and C4F8 were selected as additional gases for CF4/CHF3/Ar chemistry. CO addition increased the neutral carbon density in the plasma, C4F8 addition increased not only the fluorocarbon radicals but also the fluorocarbon ion flux. Although both gases enhanced the deposition rate of the fluorocarbon film on the Si surface, there is a difference in the mechanism of the film deposition. CO addition increased the radical sticking site in the fluorocarbon film deposited on the Si surface due to an abundant carbon density in the plasma. C4F8 addition increased the precursor radical density in the plasma due to the electron impact dissociation of C4F8. Since damage formation depends on the fluorocarbon ion flux, increasing of the fluorocarbon ion flux by C4F8 addition enhanced the damage formation.
New Three-Dimensional Wafer Bonding Technology Using the Adhesive Injection Method
Authors: Takuji Matsumoto Takuji Matsumoto , Masakazu Satoh Masakazu Satoh , Katsuyuki Sakuma Katsuyuki Sakuma , Hiroyuki Kurino Hiroyuki Kurino , Nobuaki Miyakawa Nobuaki Miyakawa , Hikotaro Itani Hikotaro Itani , Mitsumasa Koyanagi Mitsumasa Koyanagi
Published: October 2002

A new three-dimensional (3D) wafer bonding technology using the adhesive injection method has been proposed, in order to realize a real-time micro-vision system and a real shared memory. Several key technologies for 3D LSI, such as deep trench formation for buried interconnection, wafer grinding and chemical-mechanical polishing, wafer alignment and wafer bonding using the adhesive injection method, have been developed.
The Analysis of the Defective Cells Induced by COP in a 0.3-micron-technology Node DRAM
Authors: Muranaka Masaya , Makabe Kazuya , Miura Masashi , Kato Hideaki , Ide Seihachi , Iwai Hidetoshi , Kawamura Masao , Tadaki Yoshitaka , Ishihara Masamichi , Kaeriyama Toshiyuki
Published: October 2002

The influence of a crystal originated pit (COP) on the deep sub-micron dynamic-random-access-memory (DRAM), was clarified by the investigation of the defective memory cells using 0.3 microns process test-element-group (TEG) which can operate as an actual DRAM. COP constrains the growth of field oxide film and leads to degradation of the isolation characteristics between the adjacent memory cells.