bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Micro-Manipulation Using Laguerre-Gaussian Beams
Authors: Garbin Valeria , Cojoc Dan , Ferrari Enrico , Proietti Remo Zaccaria , Cabrini Stefano , Fabrizio Enzo Di
Published: September 2005

In this work we investigate the features of single-ringed Laguerre-Gaussian (LG) beams, often referred to as optical vortices, for laser trapping and micro-manipulation experiments that can not be performed using Gaussian beams. LG beams, exhibiting “doughnut”-like transversal intensity distributions and carrying orbital angular momentum (OAM) about their axis, greatly extend the capabilities of laser tweezers. LG beams can be obtained by converting the Gaussian beam generated by a common laser source, by means of phase-only diffractive optical elements (DOEs). We present a trapping system based on DOEs implemented on a liquid crystal display. Trapping of small dielectric high-index particles on the “doughnut” profile is demonstrated. Orbital angular momentum transfer to trapped particles, which are caused to rotate, is studied as a function of the doughnut radius. Moreover, low-index particles, that would be rejected by a conventional Gaussian beam, are trapped in the zero intensity region of the doughnut. Finally, trapping of low-index particles with multi-LG beams, obtained by means of DOEs, is achieved.
Electrostatic Inkjet Patterning Using Si Needle Prepared by Anodization
Authors: Ishida Yuji , Hakiai Kazunori , Baba Akiyoshi , Asano Tanemasa
Published: September 2005

A new electrostatic inkjet head composed of a Si needle having a very high aspect ratio was fabricated using a Si process combined with anodization, and fine droplets could be ejected with this head. An observation of droplet ejection with a high-speed optical camera revealed that ejection behavior can be categorized into two modes: a needle-mode ejection and an orifice-mode ejection. It was found that the mode of ejection could be determined by negative pressure applied to an ink reservoir. The mechanism of the occurrence of these two modes is discussed. The needle-mode ejection generated very fine droplets and a line of submicron width was drawn. These experimental results suggest that droplets whose size was less than a few hundreds nm were generated by the needle-mode ejection. The ejection of a photoresist material is also investigated.
Resist Elution Study for Immersion Lithography
Authors: Sato Mitsuru , Yoshida Masaaki , Ishizuka Keita , Tsuji Hiromitsu , Endo Kotaro
Published: September 2005

Resist component elution may have strong impacts on the feasibility and process establishment of immersion lithography. The amount of photo-acid-generator (PAG) fragment was investigated for a series of onium salts by changing the resist formulation and resist process. The extraction was performed in deionized water. The experiments utilized a 193 nm open-frame exposure system and compared a pair of test samples for non- and post-exposures. It was found that the elution of PAG anions indicated two opposite trends of the exposure process by increasing the number of carbon chains. It was also influenced by doping the polymer matrix with fluorine atoms in base polymers. The presoaking method effectively reduced the PAG elution only for non-exposure. The approach with a developable cover material successfully decreased the amount of PAG fragments regardless of exposure step.
Nanostructure and Composition of Carbon/Silicon Graded Film Produced by Ionization-Assisted Deposition
Authors: Mano Tsuyoshi , Sugiyama Osamu , Nakayama Hiroshi , Shibuya Yoshio , Takai Osamu
Published: September 2005

A compositionally graded film consisting of silicon and carbon compounds was developed on a metal substrate through the supply of accelerated molecular ions, which was called as an ionization-assisted deposition technique. Source gasses for the film were vaporized hexamethyldisiloxane (HMDSO) and benzene, and the adding volume ratio of HMDSO to benzene ([HMDSO]/[benzene]) was decreased in a stepped mode. The film obtained was characterized in terms of nanostructural and compositional variation along the depth direction. Transmission electron microscopic observation revealed that the film is composed of four monolithic sublayers. The interfaces between the sublayers and that between the bottom sublayer and the substrate had excellent smoothness, which was closely related to the well-ordered nanostructure of these sublayers. Furthermore, nanosized crystalline regions of silicon carbide could be observed in a high-resolution image. X-ray photoelectron spectroscopic analysis showed that the carbon content decreases but the silicon content increases simultaneously from the top sublayer to the substrate. These changes were in a stepped mode, which originated from the change in [HMDSO]/[benzene] ratio at the deposition process and contributed to the relaxation of the internal stress in the film. The graded film has a great potential as an interlayer fit for carbon-based top layers such as diamond-like carbon films with a low stress and a high adhesion.
Dry Etching of TaN/HfO2 Gate Stack Structure by Cl2/SF6/Ar Inductively Coupled Plasma
Authors: Shin Myoung Hun , Na Sung-Woong , Lee Nae-Eung , Oh Tae Kwan , Kim Jiyoung , Lee Taeho , Ahn Jinho
Published: September 2005

The dry etching characteristics of the TaN/HfO2 gate stack structure using Cl2/Ar, Cl2/SF6/Ar and Cl2/SF6/O2/Ar inductively coupled plasmas (ICPs) were investigated and the etch rates of the TaN and HfO2 layers and TaN/HfO2 etch rate selectivities were compared. The results obtained for the TaN/HfO2 etching by varying the Cl2/Ar gas mixing ratio, the top ICP electrode power, and the dc self-bias voltage (V
dc) in the Cl2/Ar plasmas showed that low etch selectivities were obtained, due to the high HfO2 etch rate. The effects of adding SF6 to the Cl2/Ar plasmas and adding O2 flow to the SF6/Cl2/Ar chemistry were investigated for the purpose of improving the etch selectivity. Etch experiments performed by varying the Cl2/SF6/Ar gas mixing ratio and V
dc value in SF6/Cl2/Ar plasmas, combined with X-ray photoelectron spectroscopy measurements, showed that the etch rates were reduced compared to those in Cl2/Ar chemistry, due to the heavy fluorination of the surface, however the etch selectivity was increased, due to a disproportionate decrease in the TaN and HfO2 etch rates. The addition of O2 flow to the SF6/Cl2/Ar plasma also increased the etch selectivity at an O2 flow rate of 5 sccm, due to the TaN etch rate being increased, while the HfO2 etch rate remained almost constant.
Improved Etched Surface Morphology in Electron Cyclotron Resonance-Reactive Ion Etching of GaN by Cyclic Injection of CH4/H2/Ar and O2 with Constant Ar Flow
Authors: Arakawa Taro , Awa Yoshiki , Ide Tomoyoshi , Haneji Nobuo , Tada Kunio , Sugiyama Masakazu , Shimizu Hiromasa , Shimogaki Yukihiro , Nakano Yoshiaki
Published: September 2005

Electron cyclotron resonance reactive ion etching (ECR-RIE) conditions for GaN using CH4/H2/Ar are investigated. GaN can be etched even with continuous etching using CH4/H2/Ar when Ar gas of a higher flow rate is introduced, but only rough etched surfaces are obtained. A cyclic injection method using CH4/H2/Ar etching gas and O2 ashing with constant Ar flow is introduced for GaN etching for the first time, and a rather high etch rate and very smooth etched surfaces are successfully obtained. The cyclic injection of CH4/H2 and O2 prevents deposition of carbon polymers by oxygen plasma, and constant Ar flow removes the surface oxidized layer formed during the O2 ashing by Ar+ ion etching. Under the optimized etching condition, an etch rate of 34 nm/min and a good morphology of etched surfaces (rms of less than 1.0 nm) are obtained.
Potential Cause of Inhomogeneous Acid Distribution in Chemically Amplified Resists for Post Optical Lithography
Authors: Yamamoto Hiroki , Kozawa Takahiro , Nakano Atsuro , Okamoto Kazumasa , Tagawa Seiichi , Ando Tomoyuki , Sato Mitsuru , Komano Hiroji
Published: September 2005

In chemically amplified resists for ionizing radiation such as an electron beam and EUV, protons of acids are mainly generated by the deprotonation of base polymers. Therefore, the acid generation efficiency depends highly on polymer structure. In recent resist formulas, partially protected poly(4-hydroxystyrene) has often been used as a base polymer. In this work, the effects of protecting groups on acid generation were investigated. We found differences in acid generation efficiency caused by protecting groups. These differences are likely to affect acid distribution.
Hybridization of Deoxyribonucleic Acid and Immobilization of Green Fluorescent Protein on Nanostructured Organosilane Templates
Authors: Tanii Takashi , Hosaka Takumi , Miyake Takeo , Kanari Yuzo , Zhang Guo-Jun , Funatsu Takashi , Ohdomari Iwao
Published: September 2005

We propose a novel process for preferential immobilization of deoxyribonucleic acid (DNA) and green fluorescent protein (GFP) onto organosilane self-assembled monolayer (SAM) templates. One of the advantages of using the organosilane SAM as the template is that it is electron-beam sensitive and, by utilizing the SAM as an alternative resist film, we can make nanopatterns on a molecular scale because the proximity effect is negligible owing to the film's thinness. An other advantage is that the organosilane SAM is repellent to both DNA and GFP. Thus, the patterned SAM can be utilized as the passivation film covering the outside of the pattern while DNA and GFP are immobilized within the pattern. We investigate two kinds of organosilane SAMs for the template. One is n-octadecyltrimethoxysilane (ODS) SAM, and the other is 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FDS) SAM. Our results indicate that the ODS SAM is more repellent to DNA than the FDS SAM and is suitable for DNA immobilization, while the FDS SAM template is suitable for GFP immobilization via biotin-avidin coupling because the FDS SAM surface prevents the nonspecific adsorption of streptavidin. Although the nonspecific adsorption of DNA and GFP on a SAM is also recognized, by controlling both the concentration and the incubation time, we can immobilize DNA and GFP preferentially onto nanopatterns of 100 nm diameter.
Development of Fast-Photospeed Chemically Amplified Resist in Extreme Ultraviolet Lithography
Authors: Watanabe Takeo , Hada Hideo , Lee Seung Yoon , Kinoshita Hiroo , Hamamoto Kazuhiro , Komano Hiroshi
Published: September 2005

In a high-annealing type resist system that employs polyhyodroxy styrene as a base resin, we found that tri-phenysulfonium cyclo(1,3-perfluoropropanedisulfone) imidate when employed as a photoacid generator (PAG) is more sensitive than tri-phenysulfonium nonaflate under extreme ultraviolet (EUV) exposure. However, their sensitivities are almost the same under KrF and EB exposures. As results of both outgassing species and FT-IR measurements, the EUV-induced reaction of cyclo(1,3-perfluoropropanedisulfone) imidate employed as an anion of PAG occurred more efficiently than that of nonaflate employed as an anion of PAG. Therefore, the anion of PAG contributes to achieve a fast photospeed under EUV exposure. Furthermore, from the sensitivity curve measurements, it is found that tri-phenylsulfonium employed as a cation increases the developing rate more than diphenyl-naphthylsulfonium employed as a cation of PAG.
As a result, we have succeeded in developing a fast photospeed chemically amplified resist that has a sensitivity of 1.1 mJ/cm2 and a partial pressure displacement accumulated in the total exposure time between after and before exposures on the order of 10-6 Pa s.
Progress in Ultrafast Photonics
Authors: Kamiya Takeshi , Tsuchiya Masahiro
Published: September 2005

Recent progress in ultrafast photonics is reviewed with special emphasis on the research and development activities in Japanese research institutions in the field of optical communication and related measurement technologies. After summarizing the physical natures of ultrashort optical pulses, selected topics are reviewed on such as (1) ultrahigh-bit-rate optical communication employing the combination of optical time division multiplexing (OTDM) and wavelength division multiplexing (WDM), (2) optical components for ultrafast photonics with emphasis on all optical switches including semiconductor optical amplifiers, cascaded second order frequency converters, semiconductor saturable absorber switches, organic dye saturable absorber switches and bistable semiconductor lasers, (3) microwave photonics, emphasizing millimeter-wave/photonic communication technologies, and (4) high-speed optical measurements featuring both compact femtosecond pulse source development and rf magnetic field imaging. Some comments on the future prospect of ultrafast photonics are also given. It is concluded that in order to bring the powerful and versatile capability of ultrafast photonics into the real world, further collaboration between photonics specialists and production engineers/information specialists is strongly desired.
Effect of Organic Additives on Ceria Slurry in Shallow Trench Isolation Chemical Mechanical Planarization
Authors: Kang Min Cheol , Kim Jae Jeong , Moon Doo-Kyung
Published: September 2005

An increase in the removal selectivity between silicon oxide and silicon nitride was attempted by adding organic additives to a ceria slurry for the application of shallow trench isolation (STI) chemical mechanical planarization (CMP). The protection behavior of poly(acrylic acid) (PAA) and the acceleration behavior of RE-610 in a ceria slurry were studied. PAA served as a protector of the silicon nitride due to the change in zeta potential. RE-610 worked as a hydration accelerator of the silicon oxide. When the two additives were added to the ceria slurry, the removal selectivity increased to 31:1. Moreover, PAA improved the stability of the ceria slurry.
GaN-Based Light-Emitting Diode with Indium–Tin–Oxide and Vertical Electrode
Authors: Kim Seong-Jin
Published: September 2005

A sapphire-etched vertical-electrode nitride semiconductor (SEVENS) light-emitting diode (LED) is fabricated by a selective wet-etching technique. The SEVENS-LED has an indium–tin–oxide (ITO) transparent metal electrode (TME) and a sapphire via hole. The SEVENS-LED exhibits excellent device performances compared with a lateral-electrode (LE) GaN-based LED formed on a sapphire substrate. The light-output power of the SEVENS-LED is ∼7 mW at a 20 mA junction current, which means 13% external quantum efficiency (EQE). The electrostatic discharge (ESD) test shows excellent ESD characteristics of the SEVENS-LED compared with those of the ITO LE-LED. The reverse ESD amplitude of SEVENS-LED is approximately 200 V, which is two times higher than that (∼100 V) of the ITO LE-LED. These improvements of ESD properties are attributed to the change of the lateral electrode to a vertical electrode, without requiring the transfer of the sapphire substrate to a conducting substrate.
Study of Noncollinear Quasi-Phase Matching Optical Parametric Amplification with Group-Velocity Matching Based on Periodically Poled Crystals
Authors: Zhao Baozhen , Liang Xiaoyan , Leng Yuxin , Wang Cheng , Du Juan , Li Ruxin , Xu Zhizhan
Published: September 2005

The properties of noncollinear optical parametric amplification (NOPA) based on quasi-phase matching of periodically poled crystals are investigated, under the condition that the group velocity matching (GVM) of the signal and idler pulses is satisfied. Our study focuses on the dependence of the gain spectrum upon the noncollinear angle, crystal temperature, and crystal angle with periodically poled KTiOPO4 (PPKTP), periodically poled LiNbO3 (PPLN), and periodically poled LiTaO3 (PPLT), and the NOPA gain properties of the three crystals are compared. Broad gain bandwidth exists above 85 nm at a signal wavelength of 800 nm with a 532 nm pump pulse, with proper noncollinear angle and grating period at a fixed temperature for GVM. Deviation from the group-velocity-matched noncollinear angle can be compensated by accurately tuning the crystal angle or temperature with a fixed grating period for phase matching. Moreover, there is a large capability of crystal angle tuning.
Infrared Wavelength Tuning by Laser Irradiation of an Ultrathin Silicon Plate
Authors: Saito Mitsunori , Matsumoto Shin-ichi , Sawai Yuta
Published: September 2005

Fabry–Pérot filters were fabricated with Si plates of 13–30 µm thickness, and the feasibility of all-optical wavelength tuning was examined. These thin Si plates exhibited pronounced interference peaks over a wide infrared wavelength region (4–16 µm). The peaks shifted to longer wavelengths by 0.1–0.2 µm, when a Si plate was exposed to a light beam from a laser diode of 0.94 µm wavelength. It was supposed from the peak shift that the refractive index of the Si plate changed by 2.4% during the laser irradiation process.
Chirp Control of Free Carrier Injection in GaAs Using Femtosecond Optical Pulses
Authors: Hattori Toshiaki , Yogi Takeshi , Hama Yoshikazu , Watanabe Naoki , Yano Ryuzi
Published: September 2005

Control of photoinjection of free carriers in bulk GaAs at room temperature was achieved by changing the chirp of the excitation light pulses having a duration in the 10 fs regime. It was observed from pump-probe measurements that the transmittance increases for negatively chirped pump pulses, which is opposite to the trend observed with other materials. The result is explained by a combination of an intrapulse pump-dump process and band-gap renormalization, and shows the possibility of a new way to control the ultrafast dynamics of many-body systems in semiconductors.
Effects of Rare-Earth Oxides on Temperature Stability of Acceptor-Doped BaTiO3
Authors: Song Young Hoon , Han Young Ho
Published: September 2005

The effects of rare-earth oxides (Yb2O3, Ho2O3, Er2O3) on the temperature stability of acceptor doped BaTiO3 dielectrics were studied. The samples doped with 1 mol % rare-earth oxides exhibited the highest dielectric constants. Substantial reductions in grain size were observed in the specimens with 1 mol % rare-earth oxides (∼0.6 µm) compared with the nondoped specimens (∼1.5 µm). As the rare-earth oxide content was increased, the Curie point progressively moved to higher temperatures. The addition of rare-earth oxides improved the temperature dependence of the dielectric constants of the acceptor-doped BaTiO3–rare-earth oxide systems over the whole temperature range studied (-55 to 150°C), and the temperature coefficient of capacitance(TCC) curves satisfied the X8R requirements for >2 mol % Yb2O3 and >3 mol % Er2O3 or Ho2O3.
Influence of Anatase–Rutile Phase Transformation on Dielectric Properties of Sol–Gel Derived TiO2 Thin Films
Authors: Kim Jin Young , Kim Dong-Wan , Jung Hyun Suk , Hong Kug Sun
Published: September 2005

Effects of annealing temperature on the structural and dielectric properties of sol–gel derived TiO2 thin films were systematically investigated. Thin films annealed at various temperatures showed pure or mixed phases of anatase and rutile. As-deposited films started crystallization below 600°C and fully crystallized into the anatase phase at 800°C, followed by transformation to the rutile phase above 850°C. Dielectric properties of thin films with various phases were studied by LCR-meter using the metal–insulator–metal (MIM) structure. Dielectric constants of thin films increased from 40 to 147 as the portion of rutile phase increased from 0 to 95%, while dielectric losses decreased from 0.011 to 0.001. Temperature dependence of dielectric constants of thin films was also investigated. The dielectric properties of TiO2 thin films were discussed in terms of phase constitution, crystallinity, and preferred orientation.
Influence of TiO2 Adhesion Layer Thickness on Properties of (Ba,Sr)TiO3 Thin Films
Authors: Kim Yong Ju , Lee Yong Soo , Lee Hee Chul
Published: September 2005

(Ba0.5Sr0.5)TiO3 thin films were deposited on Pt/TiO2/SiO2/Si substrates with various TiO2 adhesion layer thicknesses. The crystallinity of Pt thin films with (111) direction and the electrical properties of BST thin films strongly depend on the TiO2 adhesion layer thickness. TiO2 adhesion layers between the Pt and SiO2 layers with thicknesses smaller than 5 nm show good adhesion properties and a low leakage current density of BST thin films deposited on the Pt/TiO2/SiO2/Si substrate, which is lower than 8.8×10-8 A/cm2 at an applied voltage of 1 V. The optimal thickness of the TiO2 adhesion layer in the Pt/TiO2/SiO2/Si structure is very important to obtain good electrical properties of BST thin films as well as good adhesion properties.
Dependences of Electrical Properties of Thin GeSbTe and AgInSbTe Films on Annealing
Authors: Yin You , Sone Hayato , Hosaka Sumio
Published: September 2005

We studied the electrical properties of 20- and 50-nm-thick Ge2Sb2Te5 and AgInSbTe films for nonvolatile lateral transistor memory devices. Both kinds of thin films were prepared as film samples and device samples which were then annealed at temperatures from 140 to 415°C. It is known that crystal size can be effectively reduced with film thickness on the basis of X-ray diffraction analysis. The resistances of all film samples annealed at 140–415°C decreased by approximately 5–6 orders of magnitude. In the case of device samples, however, the source-drain resistances of Ge2Sb2Te5 samples were first reduced and then reversely increased and it seemed that the resistances of AgInSbTe samples did not drop. The abnormal resistance increase above the crystallization temperature may be caused by phase change and thermal expansion, as we analyzed in this paper. Finally, the resistance changes of device samples with channel lengths in the range of 0.4–3 µm were discussed from the point of view of miniaturizing the phase change memory device.
Thirty-Day-Long Data Retention in Ferroelectric-Gate Field-Effect Transistors with HfO2 Buffer Layers
Authors: Takahashi Kazuhiro , Aizawa Koji , Park Byung-Eun , Ishiwara Hiroshi
Published: September 2005

Metal–ferroelectric–insulator–semiconductor (MFIS) diodes and p-channel MFIS field-effect transistors (FETs) were fabricated and their electrical properties were characterized. These MFIS structures were formed using HfO2 as an insulating buffer layer, and SrBi2Ta2O9 (SBT) and (Bi,La)4Ti3O12 (BLT) as ferroelectric films. HfO2 buffer layers of about 8 nm physical thickness were deposited by ultrahigh-vacuum (UHV) electron-beam evaporation, then ferroelectric films of about 400 nm thickness were deposited by sol–gel spin coating. The fabricated p-channel MFIS-FETs with the SBT/HfO2 gate structure exhibited a drain current on/off ratio larger than 103 even after 30 days had elapsed. It was also found that the degradation of ferroelectricity was not pronounced even after applying 2.2×1011 bipolar pulses.
Reemission of Positrons from Mesh and Powder Moderators
Authors: Muramatsu Makoto , Ohdaira Toshiyuki , Suzuki Ryoichi
Published: September 2005

The moderation efficiency and energy distribution of reemitted positrons from W foil, W mesh and powders were investigated. The energy distribution of the reemitted positrons from the W mesh moderator became broader than that of W foil moderator. The moderation efficiency of the W mesh moderator increased when W powders were coated on the wires of the mesh. The moderation by the other powders, such as SiC whiskers, diamond and HfC, was also investigated and positron work functions were determined.
Small-Area Deposition of Light Emission Polymer by Evaporative Spray Deposition from Ultradilute Solution Technique
Authors: Ishikawa Takamasa , Fujita Katsuhiko , Tsutsui Tetsuo
Published: September 2005

The evaporative spray deposition from ultradilute solution (ESDUS) technique has enabled the preparation of organic devices from highly diluted solutions of polymer semiconductors. Here, we report another feature of this technique, the pixel-size deposition of a π-conjugated polymer. Small-area coating was carried out using a simple shadow mask with pixel-size holes. A blue-emission polymer, PFHB, was deposited through the mask. The resultant film had a pixel pattern of 10 µm separation. Moreover, a green-emission polymer, CN-PDHFV, was subsequently deposited over the first patterned layer. The pixel pattern was maintained clear without getting blurred even using the same solvent, tetrahydrofuran, for each polymer deposition. An electroluminescent (EL) device consisting of a patterned partial double layer showed a green emission from a single layer area.
Goos–Hänchen Shifts via Composite Layers of Negative- and Positive-Index Media
Authors: Kim Kyoung-Youm
Published: September 2005

Goos–Hänchen shifts via composite layers of both positive-index medium (PIM) and negative-index medium (NIM) are analyzed using the stationary phase theory. They are dependent on the evenness or oddness of the number of interfaces between different types of media (such as PIM–NIM and NIM–PIM).
High-Performance Narrow-Bandwidth Multicolor InAs/AlGaAs/GaAs Quantum Dot Infrared Photodetector
Authors: Chen Shen-De , Chen Ying-Ying , Lee Si-Chen
Published: September 2005

By introducing a 2 nm Al0.3Ga0.7As cap layer on InAs/GaAs quantum dots, a high-performance narrow-bandwidth multicolor quantum dot infrared photodetector (QDIP) with peak responses at 5.4, 9.5, and 15.8 µm was fabricated successfully. The highest peak responsivities reached 0.79, 0.47, and 0.63 A/W at a bias of -1.2 V. The two shorter-wavelength responses originating from two different-sized InAs quantum dots were due to the transitions of InAs quantum dots from the ground state to the GaAs conduction band. The separation of the two peaks was amplified by the insertion of the 2 nm AlGaAs cap layer. The longer-wavelength peak at 15.8 µm was due to the transition from the ground state to the first excited state followed by the tunneling out of small quantum dots. The increase in photocarrier lifetime by the barrier is proposed to explain the very high responsivity.
Formation Mechanism and Characterization of Ag–Metal Chelate Polymer Prepared by a Wet Chemical Process
Authors: Huang Chueh-Jung , Lin Jiang-Jen , Shieu Fuh-Sheng
Published: September 2005

In this study, a metal chelate polymer (MCP) contained Ag(0) was prepared from commercial polyvinyl acetate (PVAc) and silver nitrate (AgNO3) by a wet chemical method using concentrate formic acid (HCOOH) as solvent. The characterization of these MCP materials, and the formation mechanism that involved in the MCP system, were studied by the analyses of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM). The Ag(I) cations of silver nitrate (AgNO3) were found coordinated with polymer functional groups to form polymer–Ag(I) complexes. The XRD analysis revealed that these complexed Ag(I) ions were in-situ reduced to generate Ag(0) metal by HCOOH solvent in MCP system. The results of FTIR and NMR analyses demonstrated that there are hydrolyzed hydroxyl groups present in the MCP chains. The XPS analysis showed that the oxygen ligands that interacted with the Ag(0) were mostly contributed from the OH groups. The interaction between the reduced Ag(0) metal and the polymer chains was confirmed by transmission electron microscopy (TEM) investigation on the MCP materials.
Terahertz Wave Generation Device using Multi-Quantum Well with Transverse Electric Field
Authors: Morohashi Isao , Komori Kazuhiro , Tsurumachi Noriaki , Shimura Hisashi , Hidaka Takehiko , Watanabe Masanobu
Published: September 2005

A multi-quantum-well (MQW) device with an electric field in the MQW plane was proposed as a high-power terahertz electromagnetic wave (THz wave) generator. High-power THz waves were generated by ultrashort optical pulse excitation of the MQW device. In the excitation wavelength dependence, the amplitude of the THz wave had a peak at around exciton absorption in the MQW, which implies that the THz wave is generated by the acceleration of photoexcited carriers in the MQW region. The amplitude was proportional to an applied voltage, and the power of the THz wave at an applied voltage of 500 V was 60 times higher than that of the bulk InAs reference.
Tunneling Current Through a Single Germanium Quantum Dot
Authors: Kuo David M.-T. , Li Pei-Wen
Published: September 2005

The tunneling current through a germanium quantum dot (Ge QD) of nanometer size is studied theoretically. The energy levels and Coulomb interactions of electrons in a Ge QD are calculated using an effective mass model. In small Ge QDs, the interlevel Coulomb interactions as well as the intralevel Coulomb interactions are important in the calculation of tunneling current. The Anderson model with two energy levels is used to simulate the carrier transport in a single-electron transistor (SET) composed of a single Ge QD embedded in a SiO2 matrix. The tunneling current of the Ge SET is derived by the Keldysh–Green's function technique. It is found that the differential conductance displays multipeaks for the tunneling current through an isolated QD with the two energy levels, which is due to the statistical nature of the open system. Finally, the bistable current arising from the fourfold degeneracy state of Ge QD is discussed.
Analysis of Defect in Extreme UV Lithography Mask Using a Modal Method Based on Nodal B-Spline Expansion
Authors: Edee Kofi , Schiavone Patrick , Granet Gérard
Published: September 2005

This paper details to an electromagnetic modeling of an extreme ultraviolet (EUV) lithography mask. For that purpose, a modal method based on a spline nodal expansion (MMSNE) is presented. The results obtained using first, and second-order splines as basis functions are compared with those obtained using other modal methods, such as modal method by Fourier expansion (MMFE). The agreement between the results obtained using different methods is very good, and a convergence test is also performed. The spline nodal basis function implemented in this paper is the first step toward the realization of a multiresolution scheme that is expected to perform much more efficiently than conventional schemes.
Magneto-Optical Studies of Ferromagnetic Cr-Doped GaN Films Grown by Molecular Beam Epitaxy
Authors: Yamaguchi Kimiaki , Tomioka Hiroyuki , Yui Tatsuya , Suemasu Takashi , Ando Koji , Yoshizaki Ryozo , Hasegawa Fumio
Published: September 2005

Cr-doped GaN films were epitaxially grown on Si(111) substrates by molecular-beam epitaxy using NH3 as a nitrogen source, and the magnetic and magneto-optical properties of the films were measured. Magnetic measurements using a superconducting quantum interference device (SQUID) magnetometer revealed that the Cr-doped GaN films showed ferromagnetic behavior at 5 K. However, magnetic circular dichroism (MCD) measurements revealed that the observed ferromagnetism could not be attributed to the Cr-doped GaN itself, but to unidentified ferromagnetic precipitates in the grown layers.
Influence of the Ion-to-Atom Ratio on the Structure of CeO2Buffer Layer by Ion Beam Assisted E-Beam Evaporation
Authors: Kim Chang Su , Jo Sung Jin , Kim Woo Jin , Koo Won Hoe , Baik Hong Koo , Lee Se Jong
Published: September 2005

Using ion-beam assisted e-beam evaporation with the ion beam directed at 55° to the normal of the film plane, (200) oriented CeO2films with biaxial texture were deposited on Hastelloy C276 substrates at room temperature. The crystalline quality and in-plane orientation of films was investigated by X-ray diffraction 2θ-scan and Φ-scan, atomic force microscopy (AFM). It was shown that the in-plane and out-of-plane textures of the CeO2films were controlled by the deposition parameters. The orientation of the films was studied as a function of ion-to-atom ratio and film thickness. The ion-to-atom ratio was varied by independently adjusting the deposition rate and the ion current density. Under optimum condition, (200) textured CeO2films have been successfully grown on Hastelloy C276.
Nonlinear-Optic Silicon-Nanowire Waveguides
Authors: Yamada Hirohito , Shirane Masayuki , Chu Tao , Yokoyama Hiroyuki , Ishida Satomi , Arakawa Yasuhiko
Published: September 2005

Using a 4-mm-long compact silicon-nanowire waveguide, we demonstrated nonlinear-optic effects such as the spectral broadening of optical short pulses due to self-phase modulation and nonlinear transmittance due to two-photon absorption. At a 12 W input power level, we observed a 1.5-π nonlinear phase shift and a strong saturation of optical output power in a sample. We also estimated the third-order nonlinear coefficient n
2 and the two-photon absorption coefficient β, and compared them with those previously reported.
Microwave-Induced Suppression of Dissipative Conductivity and Its Shubnikov–de Haas Oscillations in Two-Dimensional Electron Systems: Effects of Dynamic Electron Localization and Plasma Reflection
Authors: Ryzhii Victor
Published: September 2005

We present a model for microwave photoconductivity in two-dimensional electron systems (2DESs) in a magnetic field at microwave frequencies lower than the electron cyclotron frequency when the intra-Landau level (LL) transitions dominate. Using this model, we explain the effect of the decrease in the 2DES dissipative conductivity (and resistivity) and smearing of its Shubnikov–de Haas oscillations caused by microwave radiation observed recently. The model invokes the concept of suppression of elastic impurity scattering of electrons by the microwave electric field. We calculated the dependence of the 2DES conductivity associated with intra-LL transitions as a function of the radiation and cyclotron frequencies and microwave power. We take into account the effect of plasma reflection of microwaves from 2DES resulting in a distinction between the ac microwave electric field acting on electrons and that generated by a microwave source. The obtained dependences are consistent with the results of recent experimental observations.
Synthesis and Characterization of (K0.5Na0.5)(Nb0.7Ta0.3)O3 Piezoelectric Ceramics Sintered with Sintering Aid K5.4Cu1.3Ta10O29
Authors: Matsubara Masato , Yamaguchi Toshiaki , Kikuta Koichi , Hirano Shin-ichi
Published: September 2005

The sinterability and electrical properties of (K0.5Na0.5)(Nb0.7Ta0.3)O3 ceramics were investigated as functions of K5.4Cu1.3Ta10O29 (KCT) sintering aid content. The (K0.5Na0.5)(Nb0.7Ta0.3)O3 ceramics showed a perovskite single phase and a high density at KCT contents ranging from 0.23 to 0.38 mol %. In this composition range, the electrical properties of (K0.5Na0.5)(Nb0.7Ta0.3)O3 ceramics were also improved. The planar-mode electromechanical coupling factor (k
p) of (K0.5Na0.5)(Nb0.7Ta0.3)O3 ceramics reached 0.44–0.46 in this KCT content range. A high mechanical quality factor (Q
m) of 680 was obtained at a 0.23 mol % KCT content. The (K0.5Na0.5)(Nb0.7Ta0.3)O3 ceramics prepared with 0.23 mol % KCT exhibited a field-induced strain of 0.11% at 40 kV/cm and a piezoelectric constant d
33 of 270 pm/V.
Study of Microstructural Defect Parameters in Vanadium–Aluminium Alloys using Warren–Averbach Method and Modified Rietveld Technique
Authors: Ghosh J. , Chattopadhayay S. K. , Meikap A. K. , Chatterjee S. K. , Pradhan S. K.
Published: September 2005

Detailed X-ray diffraction line profile analysis using Warren–Averbach method and modified Rietveld technique has been performed on the X-ray diffraction profile of body centered cubic vanadium-base aluminium alloys of nominal compositions in wt % as V–26% Al (Alloy I), V–24% Al (Alloy II), V–20% Al (Alloy III) and V–18% Al (Alloy IV). The microstructural parameters such as coherent domain size, microstrain within the domains and compound faults were evaluated in the alloys by applying Fourier line shape analysis. The Fourier analysis has been done taking silicon as standard. The growth fault parameter (β) has been observed to be either negligibly small or negative. This shows that growth faults are absent in this bcc system. It has also been observed that the spacing fault (αε) is totally absent in the system because the values are negative. The faulting parameter (1.5 α+ β) and deformation stacking fault α obtained from these analyses are however, not negligible.
Optical-Fiber Corrosion Sensor Based on Deposit of Au/Ni–P
Authors: Himour Abdelaziz , Abderrahmane Sihem , Beliardouh Nasser Eddine , Zahzouh Moussa , Ghers Mokhtar
Published: September 2005

The realization of an optical-fiber corrosion sensor (OFCS) has been achieved using two different methods. In the first method, a plastic clad silica (PCS) fiber whose uncladded part (2 cm in length) has been metallized through deposition using nickel–phosphorus. In the second method, metallization used gold and nickel–phosphorus. The light power [P(α)] at the exit end of the fiber is recorded as a function of the angle (α, angle of incidence) made by the axis of the fiber and a beam from a laser diode at a 670 nm wavelength applied at the entrance of the fiber. It is observed that the corrosion of the coating material (nickel–phosphorus) modifies the P(α) curves, be it by immersion in phosphoric acid solutions. The full width at half-maximum of these curves increases with increasing corrosion pit density. Kinetic curves of corrosion have been obtained for different concentrations of phosphoric acid. This type of sensor is important because it can be inserted in metallic infrastructures to monitor the corrosion state of the structure in situ.
Surface Modification of CdTe Crystal by Plasma Treatment Using Various Gases
Authors: Higa Akira , Nishihira Atsushi , Toyama Hiroyuki , Yamazato Masaaki , Maehama Takehiro , Ohno Ryoichi , Toguchi Minoru
Published: September 2005

Plasma treatments using various gases have been applied to CdTe(111) surfaces. The induced surface layer composition and morphology were analyzed by X-ray photoelectron spectroscopy and field-emission scanning electron microscopy. He and Ar plasma treatments yielded an approximately stoichiometric surface and morphologies with a pyramidal structure. The surface with the H2plasma treatment had ball-like particles and was Cd-rich. Furthermore, the surface with the O2plasma treatment was almost oxidized. An Al/CdTe Schottky contact formed on the surface after the He, Ar, and H2plasma treatments showed good rectification properties due to elimination of a Te-rich layer.
Field-Emission Characteristics of Carbon Nanotube Single Tip Grown on Si Cone
Authors: Yoshimoto Tomomi , Iwata Tatsuo , Matsumoto Kazuhiko
Published: September 2005

The field-emission characteristics of a carbon nanotube single tip were investigated as functions of annealing temperature. The current–voltage (I–V) characteristics (linearity of Fowler–Nordheim plots as well as emission pattern) were altered by annealing in the temperature range from 470 to 1270 K. On the other hand, the voltages required for the same emission current were relatively unaltered. The emission current showed little dependence on the temperature of the carbon nanotube (CNT) single tip. The fluctuation of the emission current was markedly improved by increasing the annealing temperature.
Frequency Stabilization of Diode Laser Using Dichroic-Atomic-Vapor Laser Lock Signals and Thin Rb Vapor Cell
Authors: Imanishi Sayaka , Tanaka Utako , Urabe Shinji
Published: September 2005

We report the frequency stabilization of a diode laser by applying the dichroic-atomic-vapor laser lock (DAVLL) method to a thin Rb vapor cell. A 1-mm-long Rb vapor cell is used to obtain a sub-Doppler spectrum that is required for frequency locking, which is easier than in the case of using a saturated absorption spectrometer. A 794-nm diode laser is tuned to the Rb D
1 line, and sub-Doppler signals are observed by introducing a pumping beam and a probe beam in a perpendicular direction. We obtain error signals by subtracting the signals of σ+ polarized beams from that of σ- polarized beams in the presence of a magnetic field and stabilized the 794 nm diode laser frequency without modulating laser parameters. The stability of the 794-nm diode laser is evaluated using other independently stabilized diode laser.
Short-Circuit Current Density Behavior of Dye-Sensitized Solar Cells
Authors: Asano Tsuyoshi , Kubo Takaya , Nishikitani Yoshinori
Published: September 2005

Short-circuit current densities (J
scs) were measured on two kinds of dye-sensitized solar cells (DSCs). The dependences of J
sc on the diffusion coefficient of I3
- and the cell gap are discussed using relevant model equations for the DSC. In the lower diffusion coefficient region, the DSC operates under an I3
- diffusion-limiting condition and, under this condition, narrowing the cell gap is a simple and effective way to increase the J
sc. The J
sc of a gel-type polymeric-electrolyte-based DSC with a cell gap of 20 µm is verified to be equal to that of a liquid electrolyte-based DSC.
Exponential Rule for Light-Scattering Sizing of Bubbles or Drops
Authors: Hayashi Shigeo
Published: September 2005

Numerical calculations of Mie scattering have shown that the radius a of a bubble in water, e.g., that of a sonoluminescing one, can be given from the scattered light intensity I by a∝I
α, where for vertical linear polarized light α is 0.44 at a scattering angle of 80° and 0.48 between 90 and 100°. For unpolarized light, α is 0.42 at 80° and 0.47 between 90 and 100°. This exponential relationship is found to hold in many other systems, including bubbles in organic liquids and drops in air, but the applicable range depends on refractive index and absorption. The existence of light absorption may alter the applicability of the rule significantly.
A Micromachined Microwave Switch Fabricated by the Complementary Metal Oxide Semiconductor Post-Process of Etching Silicon Dioxide
Authors: Dai Ching-Liang , Peng Hsuan-Jung , Liu Mao-Chen , Wu Chyan-Chyi , Hsu Heng-Ming , Yang Lung-Jieh
Published: September 2005

In this study, we investigate the fabrication of a micromachined microwave switch using the commercial 0.35 µm double polysilicon four metal (DPFM) complementary metal oxide semiconductor (CMOS) process and the post-process of only one maskless wet etching. The post-process has merits of easy execution and low cost. The post-process uses an etchant (silox vapox III) to etch the silicon dioxide layer to release the suspended structures of the microwave switch. The microwave switch is a capacitive type that is actuated by an electrostatic force. The components of the microwave switch are coplanar waveguide (CPW) transmission lines, a suspended membrane and supported springs. Experimental results show that the driving voltage of the switch is about 17 V. The switch has an insertion loss of -2.5 dB at 50 GHz and an isolation of -15 dB at 50 GHz.
Rigorous Simulation of Line-Defects in Extreme UV Masks
Authors: Schiavone Patrick , Payerne Renaud
Published: September 2005

In this study, rigorous electromagnetic simulation is used to investigate the behavior of line defects in extreme UV (EUV) masks. Using the modal method by Fourier expansion (MMFE), the geometry of the structure as well as the polarization state can be handled. A simple analytical model has been developed in order to generate the input geometry for the simulations. The deposition conditions can be mimicked by changing an empirical parameter representing the planarization properties of the process. The influence of the defect size and of its position in the multilayer mirror is analyzed. The position of the defect with respect to an absorber feature is very important and is also considered. It is shown that the size of the nucleation particle by itself is not a relevant parameter to describe a defect. The process conditions greatly modify the propagation of the defect into the multilayer mirror and induce a very large variation in its printability. Some defects that do not affect the surface of the mirror can induce a nonnegligible intensity drop.
Ultra-High-Sensitivity Measurement of Metal Thin Film Thickness by Photothermal Mirage Detection Method through Sample Surface Coating and Use of Semi-Cylindrical Lens
Authors: Okamoto Yoshitsugu , Kurobe Masanori , Yarai Atsushi , Nakanishi Takuji
Published: September 2005

Methods to achieve ultra-high-sensitivity measurement of metal thin-film thickness by photothermal mirage detection are proposed. These methods apply 1) sample surface coating and 2) a semi-cylindrical lens for pumping beam focusing. Consequently, successful measurements are taken for thicknesses of less than several hundred nm. The semi-cylindrical lens plays a critical role in the measurements, and the sample surface coating significantly improves measurement sensitivity to about 2.5 times higher than the results for samples without coating.
Application of a Scanning Thermal Nano-Probe for Thermal Imaging of High Frequency Active devices
Authors: Joodaki Mojtaba , Janus Pawel , Gotszalk Teodor , Kompa Günter , Edinger Klaus , Rangelow Ivo W.
Published: September 2005

The first application of a new thermal nano-probe based on the changes of electrical resistivity of a nanometer-sized filament with temperature has been presented for the thermal imaging of microwave power active devices. The integration of the filament the fabrication process of the novel thermal probe with a spatial resolution better than 80 nm and a thermal resolution of the order of 10-3 K have already been presented in reference [J. Microelectron. Eng. 57–58 (2001) 737]. To demonstrate the capability of the novel thermal nano-probe the measurements have been successfully performed on a 30 fingers GaAs metal–semiconductor field-effect transistor (GaAs-MESFET) with a maximum power dissipation of 2.5 W. The bias circuit has been designed to suppress the undesired microwave oscillations in the transistor. In this case the power dissipation is equal to the dc power input. The near-field measurements using the nano-probe are compared with infrared measurement and three-dimensional finite element static thermal simulations. The good agreement between simulations and measurements confirms the high capability of the nono-probe for these applications.
Expansion of Vibration-Based Sphere-Pack Technology to Binary Mixture Including Irregular Particles
Authors: Ishii Katsunori , Kihara Yoshiyuki , Fujii Kan-ichi
Published: September 2005

Vibration-based sphere-pack technology has been successfully expanded to a binary mixture including irregular particles. The packed fraction (PF) in a single component of an irregular particle exhibits a trend of increasing with shape improvement. An increase of PF of 8% is realized via grinding of the irregular particle toward an edgeless or round shape. The PF of a binary component mixture is roughly determined by the condition of large particles, being almost independent of that of small particles.
Characterization of Chemical Vapor Deposition Growth Yields of Carbon Nanotube Transistors
Authors: Lin Jun , Xuan Patrick , Bokor Jeffrey
Published: September 2005

We investigate the dependence of chemical vapor deposition (CVD) growth yield of carbon nanotube (CN) transistors on both the device size and CN formation process. Statistical data shows that high fabrication yields of 90% can be achieved for a chip of CN transistors. Although no special efforts at orientation were made, the CNs connecting the source and drain were generally found to be aligned perpendicularly to the source and drain.
Carbon Beads on Semiconductor Nanowires
Authors: Kohno Hideo , Yoshida Hideto , Kikkawa Jun , Tanaka Koji , Takeda Seiji
Published: September 2005

We report the beading of carbon-rich material on semiconductor nanowires. It appears that the beading was due to hydrocarbon contamination which adhered to the nanowires after they grew. Our result opens the possibility of fabricating new types of nanowires using secondary adhesive viscous materials.