bluuebunny/crossref_metadata_2025 huggingface dataset:
Raised Source/Drain on Different Integration Schemes for Sub-Micro CMOS
Authors: Cheng Ellen , Lee Yi-Chia , Chiang Yi-Ying
Published: July 2005

The performance of raised source/drain by selective epitaxial growth (SEG) using two different integration sequences were compared in this article. It was observed that inserting SEG layer after source/drain annealing provided more benefits on reduction of junction leakage and parasitic resistance and 12% I
on improvement at I
off=10 nA on PMOS.
Silicon-Atom Induced Fermi-Level Pinning of Fully Silicided Platinum Gates on HfO2 Dielectrics
Authors: Kadoshima Masaru , Akiyama Koji , Mise Nobuyuki , Migita Shinji , Iwamoto Kunihiko , Yasuda Naoki , Tominaga Koji , Ikeda Minoru , Satake Hideki , Nabatame Toshihide , Toriumi Akira
Published: July 2005

Fully silicided platinum gates have been proposed as metal gate electrodes for scaled complementary metal oxide semiconductor field-effect transistors (CMOSFETs). The Pt monosilicide (PtSi) phase was formed on gate dielectrics by a full silicidation reaction at 400°C. PtSi gate electrodes on SiO2 possess a high effective work function of 4.9 eV, which could be used as a possible metal gate electrode for p-MOSFETs, while at the PtSi/HfO2 interface, Fermi-level pinning is observed independent of the PtSi fabrication process. The Fermi-level pinning at the PtSi/HfO2 interface is comparable to that at the poly-Si/HfO2 interface, and Fermi-level pinning does not occur at the Pt/HfO2 interface. These results show that Fermi-level pinning is induced by the presence of silicon atoms at the HfO2 upper interface.
Effects of the Metallurgical Properties of Upper Cu Film on Stress-Induced Voiding (SIV) in Cu Dual-Damascene Interconnects
Authors: Abe Mari , Furutake Naoya , Saito Shinobu , Inoue Naoya , Hayashi Yoshihiro
Published: July 2005

Stress-induced voiding (SIV) is a serious problem in Cu dual-damascene interconnects (DDIs). The stress gradient under vias is the driving force of vacancy diffusion and void generation, therefore stress control in Cu-DDI is an important factor for suppressing SIV. In this study, the stress effect of upper Cu film on SIV in lower Cu lines is investigated, and the stress distribution in Cu-DDI is analyzed by finite element analysis. It is found that SIV in the lower Cu lines is strongly affected not only by the width of lower lines but also by the metallurgical properties of the Cu film in upper metals. Suppression of tensile stress in the via of the upper Cu film decreases the stress gradient in the lower line around the via, and eventually, the driving force of vacancy diffusion to the via bottom. Control of the metallurgical properties to suppress Cu creep during annealing is a key factor for decreasing SIV in lower Cu lines. High-temperature deposition of Cu film with a small coefficient of thermal expansion (CTE) is a solution to suppressing SIV failure in Cu-DDIs.
1.2 nm HfSiON/SiON Stacked Gate Insulators for 65-nm-Node MISFETs
Authors: Saitoh Motofumi , Terai Masayuki , Ikarashi Nobuyuki , Watanabe Heiji , Fujieda Shinji , Iwamoto Toshiyuki , Ogura Takashi , Morioka Ayuka , Watanabe Koji , Tatsumi Toru , Watanabe Hirohito
Published: July 2005

We have investigated a Hf-based CMOSFET fabrication method that would enable the high performance and low gate leakage current that are required for the 65-nm-node CMOS devices. To suppress the gate leakage in a gate stack with an equivalent oxide thickness (EOT) of 1.2 nm, the upper layer of HfSiO film was thickened and nitrided. The nitridation improves the dielectric constant, allowing the use of a thicker HfSiO layer. The mobility was improved by lightly nitriding the bottom SiO2 interface layer, which suppresses the interfacial trap generation. Such techniques enabled us to achieve a good EOT vs I
g relationships. The I
g at an EOT of 1.2 nm was reduced by three orders of magnitude as compared with that with a SiO2 gate insulator. High mobilities, 87% of that of a SiO2 MOSFET for an NFET and 96% for a PFET, were also obtained.
Temperature Dependence of Off-Current in Bulk and Fully Depleted SOI MOSFETs
Authors: Miyaji Kousuke , Saitoh Masumi , Nagumo Toshiharu , Hiramoto Toshiro
Published: July 2005

Re-examinations of the temperature dependence of off-current (I
off) in metal oxide semiconductor field-effect transistors (MOSFETs) have been carried out, from 0.25 µm to 65 nm technology nodes comparing bulk MOSFETs to fully depleted silicon on insulator (FD SOI) MOSFETs. Analytical calculations and two-dimensional (2D) device simulations are performed, and the ratio of I
off at a high temperature to that at room temperature has been focused on for discussion. The temperature dependence of I
off consists of two components: subthreshold factor component (S component) and threshold voltage component (V
th component). It is found that the V
th component determines the relative merits of bulk and FD SOI MOSFETs, and originates from the difference in the temperature dependence of V
th. It is also found from the simulation that, although the advantage of FD SOI MOSFETs remains when the short-channel effect can be neglected, it diminishes when the short-channel effect is dominant as the technology node advances.
Wide-Band Two-Stage Erbium-Doped Fiber Amplifier Module in Parallel Configuration
Authors: Yeh Chien-Hung , Chen Chih-Yang , Lee Chien-Chung , Chi Sien
Published: July 2005

We propose and experimentally demonstrate a two-stage broadband erbium-doped fiber amplifier module with a coupled structure over a gain bandwidth of 1520 to 1600 nm. As a result, 35.4 and 38.1 dB peak gains can be achieved at 1532 and 1568 nm, respectively, over the operation range. This proposed amplifier can also be used as a broadband amplified-spontaneous-emission light source.
Demonstration of Dopant Profiling in Ultrathin Channels of Vertical-Type Double-Gate Metal-Oxide-Semiconductor Field-Effect-Transistor by Scanning Nonlinear Dielectric Microscopy
Authors: Masahara Meishoku , Hosokawa Shinichi , Matsukawa Takashi , Endo Kazuhiko , Naitou Yuichi , Tanoue Hisao , Suzuki Eiichi
Published: July 2005

We demonstrate dopant profiling in ultrathin channels (UTCs) (T
c=18–58 nm) of vertical-type double-gate metal-oxide-semiconductor field-effect-transistors (DG MOSFET) by scanning nonlinear dielectric microscopy (SNDM). The vertical UTCs were fabricated by orientation-dependent-wet etching. Using ion implantation technology and subsequent furnace annealing, n+-p junctions, which correspond to the source/drain of the vertical-type DG MOSFET, were formed in the upper part of the UTC. To improve the accuracy of the vertical dopant profile in the UTC, the cross-section of the UTC was magnified by beveling with a small angle by chemical mechanical polishing. Using such a beveled sample, the dopant depth profile in the vertical UTC has been measured by SNDM with nanometer-scale resolution. On the basis of the measurements of the dopant profile, an effective channel length for the vertical DG MOSFET has also been estimated quantitatively.
Study of Electronic Properties by Persistent Photoconductivity Measurement in GaxIn1-xNyAs1-y Grown by MOCVD
Authors: Hsu S. H. , Su Y. K. , Chuang R. W. , Chang S. J. , Chen W. C. , Chen W. R.
Published: July 2005

Electronic properties of GaInNAs thin films have been investigated by the temperature-dependent Hall-effect and persistent photoconductivity (PPC) measurements. The Ga
x
In1-x
N
y
As1-y
thin films were grown by metal-organic chemical vapor deposition (MOCVD) on GaAs(100) substrates. High resolution X-ray diffraction (HR-XRD) and photoluminescence (PL) were used to determine the crystal quality. Compared with the N-free sample, the mobility of the GaInNAs sample quenched significantly due to the lattice defects induced by the small amount of nitrogen atoms incorporated during growth. The free carrier concentration of the GaInNAs samples was not affected by the increasing temperature ranging from 120 K to 400 K. Persistent photoconductivity (PPC) was also observed in this material, and the properties of PPC were found to depend on the temperature and nitrogen content. The relationship between trend toward saturation of the free carrier concentration of the temperature-dependent Hall measurement and PPC is also discussed.
Nitride based Power Chip with Indium-Tin-Oxide p-Contact and Al Back-Side Reflector
Authors: Chang Chia-Sheng , Chang Shoou-Jinn , Su Yan-Kuin , Chen Wei-Shou , Shen Chien-Fu , Shei Shih-Chang , Lo Hsin-Ming
Published: July 2005

Nitride-based large size (i.e. 1 mm×1 mm) indium-tin-oxide (ITO) light emitting diodes (LEDs) were successfully fabricated. In order to enhance the output intensity of power chips, Al reflector was deposited by e-beam evaporator on the chip backside. It was found that the 350 mA output power was 84.8 mW (W-P-E=7.2%) at 460 nm for the power chip with ITO as p-contacts and Al as back-side reflector. It was also found that ITO power chip with Al reflector was more reliable.
Noise Analysis of AlGaN/GaN Metal-Oxide-Semiconductor Heterostructure Field Effect Transistors with Photochemical-Vapor Deposition SiO2 Layers
Authors: Chiou Yu-Zung
Published: July 2005

Low frequency noise of AlGaN/GaN metal-oxide-semiconductor heterostructure field effect transistors (MOS-HFETs) with a photo-CVD SiO2 gate oxide was investigated as a function of gate bias (from V
gs=-8 V to V
gs=4 V) in the linear region. In the linear region, the measured noise spectra were fitted well by the 1/f law up to 10 kHz. The normalized noise power density of the MOS-HFETs was proportional to V
gs
-1 when -4 V<V
gs<0 V and were independent of the gate voltage when the devices were biased at V
gs>0 V. Moreover, the normalized noise-power densities of both devices were inversely proportional to the drain-source distance when V
gs>0 V. All the experiment data can be well explained by Hooge's Law. The Hooge's coefficients αch and αs were estimated to be 10-3 approximately.
Low-Frequency Noise Generated from High-Field Region in AlGaAs/InGaAs HEMTs
Authors: Wada Masanori , Nakamoto Takayuki , Hamayoshi Shinichi , Higuchi Katsuhiko
Published: July 2005

We have investigated the effects of a high-field region on low-frequency noise (LFN) in AlGaAs/InGaAs HEMTs using a two-region model and experiments. The negative cross-correlation between the LFN generated from a low-field region and that from a high-field region is found for the first time. This negative cross-correlation depends on gate and drain voltages, and increases with gate voltage. Due to this negative cross-correlation, the observed LFN is almost constant because the cross-correlation cancels out the increase in the LFN generated from the low-field region.
Fabrication of p-Si/β-FeSi2/n-Si Double-Heterostructure Light-Emitting Diode by Molecular Beam Epitaxy
Authors: Takauji Motoki , Li Cheng , Suemasu Takashi , Hasegawa Fumio
Published: July 2005

We have fabricated p-Si/β-FeSi2 film/n-Si double-heterstructure (DH) light-emitting diodes (LEDs) on Si(111) substrates by molecular beam epitaxy (MBE). It was found that both the thickness of an undoped Si overlayer and subsequent annealing temperature were key parameters in preventing the aggregation of the β-FeSi2 film and the successful formation of a Si/β-FeSi2 film/Si DH LED on Si(111). A 1.6 µm electroluminescence (EL) was realized at room temperature (RT) at a current density higher than 78 A/cm2 by increasing the thickness of the β-FeSi2 active region from 90 nm to 250 nm, suggesting that there exist numerous defects at Si/β-FeSi2 heterointerfaces.
Fabrication of Large-Area GaN-Based Light-Emitting Diodes on Cu Substrate
Authors: Chu Jung-Tang , Huang Hung-Wen , Kao Chih-Chiang , Liang Wen-Deng , Lai Fang-I , Chu Chen-Fu , Kuo Hao-Chung , Wang Shing-Chung
Published: July 2005

A large-area GaN-based light-emitting diode (LED) 1000×1000 µm2 in size with a p-side down configuration was fabricated using wafer bonding and laser lift-off (LLO) techniques. The thin GaN LED was transferred onto a copper substrate without peeling or cracks. The large-area LEDs showed a uniform light-emission pattern over entire defined mesa area without a transparent contact layer on the p-type GaN. The operating current of the large-area LEDs can be driven up to 1000 mA with continuously increasing light output-power. The light output-power is 240 mW with a driving current of 1000 mA. Large-area emission and high current operation make the LLO-LEDs applicable to high-power LED applications.
Observation of 1.55 µm Light Emission from InAs Quantum Dots in Photonic Crystal Microcavity
Authors: Iwamoto Satoshi , Tatebayashi Jun , Fukuda Tatsuya , Nakaoka Toshihiro , Ishida Satomi , Arakawa Yasuhiko
Published: July 2005

We have observed light emission at a wavelength of 1.55 µm from InAs quantum dots (QDs) embedded in a high-quality-factor photonic crystal (PhC) microcavity for the first time. The InAs QDs were grown on a (100) GaAs substrate and the photoluminescence measurement was performed at room temperature. The cavity quality factor Q reaches 2700, which is close to the resolution limit of our measurement system. Due to the small mode volume V of the PhC cavity, Q/V increases up to 3400×(n/λ)3. These are the highest values ever reported for microcavities containing QDs emitting in a spectral range around 1.5 µm. Details of the optical properties of the microcavity, such as polarization and pump power density dependences are also discussed.
Improvement of Mesa-Sidewall Leakage Current Using Benzocyclobuten Sidewall Process in InGaAs/InP MSM Photodetector
Authors: Chiu Wei-Yu , Huang Fan-Hsiu , Wu Yen-Shian , Lin Don-Ming , Chan Yi-Jen , Chen Shu-Han , Chyi Jen-Inn , Shi Jin-Wei
Published: July 2005

In recent decades, metal-semiconductor-metal (MSM) photodetector for optical fiber communication applications have been studied extensively. The dark current in MSM PD is an important parameter that can be reduced by schottky barrier enhancement and fabrication process. By employing a benzocyclobuten (BCB) sidewall passivation process, the leakage issue between Schottky metal fingers and mesa sidewalls can be avoided. Moreover, the parasitic capacitance can also be decreased due to the low dielectric constant of BCB. The BCB passivation process decreases the dark current density from 11 nA/µm2 to 5.7 pA/µm2.
Mode-Coupling Effects in Non-Equilibrium Green's Function Device Simulation
Authors: Takeda Hiroshi , Mori Nobuya
Published: July 2005

We performed non-equilibrium Green's function (NEGF) simulations for a double-gate (DG) silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect-transistors (MOSFETs) with an extra SiO2 bump, which enables us to modulate the mode-energy profile. Comparing the numerical results of real-space, coupled-mode space, and decoupled-mode space methods for expanding the Green's function, we estimate the accuracy of the mode space scheme and study mode-coupling effects on the source-to-drain current.
Fabrication and Characterization of 1 k-bit 1T2C-Type Ferroelectric Memory Cell Array
Authors: Kim Hyun-Soo , Yamamoto Shuu'ichirou , Ishikawa Toru , Fuchikami Takaaki , Ohki Hiroshi , Ishiwara Hiroshi
Published: July 2005

A 1 k-bit 1T2C-type ferroelectric memory cell array has been designed and fabricated by combination of a 0.35 µm design rule for the complementary metal-oxide-semiconductor (CMOS) process and a 3 µm design rule for the ferroelectric and interconnection processes. Basic operations such as random access writing and readout operations, nondestructive data readout for more than 104 readout pulses, data retention for 10 days, and data disturbance characteristics for more than 104 unipolar pulses have been demonstrated in the fabricated 1T2C-type cell array.
Large Modulation of Conductance in Interdigital-Gated HEMT Devices Due to Surface Plasma Wave Interactions
Authors: Hashim Abdul Manaf , Kasai Seiya , Hashizume Tamotsu , Hasegawa Hideki
Published: July 2005

To investigate the presence of interactions between surface plasma waves of carriers in a two-dimensional electron gas (2DEG) at AlGaAs/GaAs heterostructure and electromagnetic space harmonic slow waves, interdigital-gated high-electron-mobility transistor (HEMT) devices were fabricated, and their input admittances were measured in the microwave region of 1–15 GHz. A large modulation of conductance, more than 1000 mS/mm, was observed. The conductance modulation was controlled by a drain-source voltage and showed a peak at a certain frequency whose position could be controlled by changing the pitch of the interdigital gates. The observed conductance and capacitance characteristics were in good agreement with the transverse magnetic (TM) mode analysis taking into account a nonuniform field distribution along the 2DEG channel. The result seems to prove the existence of surface plasma wave interactions even under the strongly collision-dominant situation in the microwave region and provides great hope for increased interactions at THz frequencies under nearly collision-free conditions.
Transmission Characteristics of Gaussian Monocycle Pulses for Inter-Chip Wireless Interconnections Using Integrated Antennas
Authors: Kimoto Kentaro , Kikkawa Takamaro
Published: July 2005

Performance of integrated dipole antennas on Si substrates was investigated for inter-chip signal transmission in wireless interconnections for Si ultra-large scale integrated circuits (ULSI). Linear dipole antennas 4 mm long were fabricated on P-type Si substrates with a resistivity of 10 Ω·cm in an inter-chip stacked structure. Inter-chip antenna transmission gains were measured for the dipole antennas at a vertical distance of 2.86 mm and a horizontal distance of 3 mm when Si substrates with a resistivity of 2.29 kΩ·cm were inserted. A transmission gain of -30 dB and no dependence on vertical distance were observed. Gaussian monocycle pulses with a pulse width of 70 psec could be transmitted successfully in the inter-chip stacked structure. Antenna transmission gain and peak-to-peak voltage between Si chips were improved using a high resistivity Si substrate.
Interface Modification in Organic Thin Film Transistors
Authors: Wu Bo-Tan , Su Yan-Kuin , Tu Ming-Lung , Wang An-Chang , Chen You-Sian , Chiou Yu-Zung , Chiou Yii-Tay , Chu Chun-Hsun
Published: July 2005

The octadecyltrichlorosilane (OTS) solutions with three solvents, hexadecane, toluene, and ethanol, were acted as the interface chemical modifiers to advance the characteristics of organic thin-film transistors (OTFTs). The electrical characteristics of the organic thin-film transistors with modification were obviously enhanced, especially in mobility, on/off current ratio and subthreshold slope. From the data of X-ray diffraction (XRD), contact angle and atomic force microscope (AFM) measurement, it could be understood that the quality of the organic thin film had been improved due to the change of silicon dioxide surface energy. In this report, the best device was been treated in the OTS/toluene or hexadecane solutions with 1% volume concentration.
Investigation of the Electrostatic Phenomena at Pentacene/Metal Interface by Second-Harmonic Generation
Authors: Manaka Takaaki , Suzue Yuuma , Iwamoto Mitsumasa
Published: July 2005

Optical second-harmonic generation (SHG) in a vacuum evaporated pentacene thin film deposited on an aluminum (Al) surface was investigated on the basis of the electrostatic phenomena occurring at the interface. The SH process in centrosymmetric molecules is activated by the static electric field, i.e., the surface potential. Since electric field-induced SHG is classified as a third-order nonlinear optical process, its resonant condition differs from the one originating in the electric quadrupole. In the SHG spectrum of the pentacene/Al structure, two prominent peaks were observed at approximately 560 nm and 660 nm, whereas only one peak located at approximately 560 nm was observed in pentacene/glass structure. These results are discussed on the basis of the surface potential formed in the pentacene layer deposited on Al due to the displacement of electrons from metal to pentacene. The effects of photoirradiation on the SH spectrum were investigated to confirm the presence of the electric field-induced SHG.
Electronic and Transport Properties of Doped Organic Molecules for Molecular Wire Applications
Authors: Belosludov Rodion V. , Farajian Amir A. , Baba Hidetoshi , Mizuseki Hiroshi , Kawazoe Yoshiyuki
Published: July 2005

Electronic transport through a doped polythiophene (PT) fragments and metal porphyrin molecules, which can be used in molecular wire applications, has been investigated using the nonequilibrium Green's function formalism of quantum transport and the density functional theory (DFT) of electronic structures with local orbital basis sets. The conductance of a PT fragment is increased by Na doping. A Na-doped PT chain can be isolated using a nanotube of cross-linking α-cyclodextrin (CD) molecules. The results also show that the metal atoms enhance the conductivity of the porphyrin molecule. Moreover, the Au-molecule contact is a very important factor for realizing a molecular wire based on porphyrin molecules because the conductance strongly depends on the type of contact.
Selective Deposition of Gold Nanoparticles on SiO2/Si Nanowires for Molecule Detection
Authors: Sheu Jeng Tzong , Chen Chen Chia , Huang Po Chun , Lee Yaw Kuen , Hsu Meng Lieh
Published: July 2005

The selective deposition of gold nanoparticles on the surface of N-(2-Aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS)-pretreated silicon nanowire (SiNW)s for molecule detection was demonstrated. The SiNWs were fabricated by scanning probe lithography (SPL) and tetramethyl ammonium hydroxide (TMAH) wet etching. The width and height of the SiNWs were 60 nm and 10 nm, respectively. The gold nanoparticles were synthesized by the chemical reduction method. The electronic properties of the SiNWs in response to the binding of different molecules on the surface of the SiNWs subsequently were discussed. A dynamic observation of the change in conductance was conducted to monitor the reaction between gold nanoparticles and the AEAPTMS-pretreated surface of the SiNWs. The reaction of gold nanoparticles on the surface of the SiNWs took about 750 s before conductance saturation. Finally, an engineered enzyme, KSI-126C, with a thiol terminal was designed to bind with the gold nanoparticles on the surface of the SiNWs. Shifts in turn-on voltage in I–V
ds characteristics have clearly been observed after the binding of molecules and gold nanoparticles.
Basic Study to Develop Biosensors Using Surface Acoustic Waves
Authors: Kim Gi-Beum , Chong Woo-Suk , Kwon Tae-Kyu , Hohkawa Kohji , Hong Chul-Un , Kim Nam-Gyun
Published: July 2005

In this paper, we present a study of the bonding between piezoelectric substrates and semiconductor materials. We have studied [O. S. Wolfbesis: Fiber Optic Chemical Sensors and Biosensors, 1st ed. (CRC Press, Boca Raton, 1991) p. 21.] the surface state (hydrophilic) of GaAs, LiNbO3 and quartz substrates after different treatments methods [R. Hughes, A. Ricco, M. Butler and S. Martin: Science 254 (1991) 74.], the effects of migration of water molecules out of bonding surfaces induced by microwave and laser radiation. When Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) is used as a piezoelectric material, we have evaluated if PMN-PT can be made practically available for a new surface acoustic wave (SAW) biosensor detecting protein. The experimental results clarified that improvements in the bonding process are effective in obtaining a stronger bonding interface between the piezoelectric substrate and semiconductor materials. The frequency filtering of the central frequency of the PMN-PT substrate is also superior to that of the LiTaO3 substrate, but the result was not completely satisfactory. However, the electromechanical coupling coefficient of the PMN-PT substrate is excellent, therefore it will be used as a SAW sensor, in the near future, provided that new interdigital transducer (IDT) design will also be available to increase the frequency of filtering.
Liquid-Crystal Fresnel Zone Plate Fabricated by Microrubbing
Authors: Honma Michinori , Nose Toshiaki
Published: July 2005

A novel liquid-crystal (LC) Fresnel zone plate (FZP) is fabricated only by the LC molecular alignment process without the need for surface relief structures and patterned electrodes. It is theoretically described that the Fresnel-lens-like phase profile is achieved under optimum LC molecular orientation conditions and the polarization state of incident light, that is, the retardation of the LC cell is (n+1/2)λ (n is an integer) and the incident light is circularly polarized. The optical properties of the fabricated LC FZP are experimentally investigated. Good focusing properties are confirmed (the full width at half maximum of the spot is approximately 8% larger than that of the diffraction limit) and the light intensity of the focusing spot is found to be controllable by adjusting applied voltage.
Liquid-Crystal-Based Fourier Optical Spectrum Analyzer without Moving Parts
Authors: Lu Yan-qing , Du Fang , Wu Yung-Hsun , Wu Shin-Tson
Published: July 2005

We propose and demonstrate a liquid-crystal (LC)-based Fourier optical spectrum analyzer (FOSA). The FOSA consists of a birefringent filter array with an embedded LC phase modulator. The LC phase modulator is used to control the phase difference between two orthogonally polarized beams to avoid mechanical movement in conventional Fourier transform spectrometers. The detailed operation principle of this FOSA is described. A single-LC-based 6-stage FOSA is experimentally demonstrated, and the results obtained using such a FOSA show good agreement with the results measured using a reference spectrometer.
AlGaAs/GaAs NpnP Depleted Optical Thyristor Using Bottom Mirror Layers
Authors: Choi Woon Kyung , Kim Doo Gun , Choi Young Wan , Lee Seok , Woo Deok Ha , Kim Sun Ho
Published: July 2005

A novel fully depleted optical thyristor (DOT) using quarter wavelength reflector stacks (QWRS) is proposed. QWRS are employed as bottom mirrors to enhance the emission efficiency as well as optical sensitivity. To analyze their switching characteristics, s-shapes nonlinear current–voltage curves were simulated and the reverse full-depletion voltages (V
negs) of DOTs were obtained as a function of semiconductor parameters using a finite difference method associated with a current-oriented method. The fabricated DOTs show sufficient nonlinear s-shaped current–voltage (I–V) characteristics, and switching voltage changes with and without bottom mirrors are 1.82 V and 1.52 V, respectively. Compared to a conventional DOT, this device with the bottom mirror shows about 20% and 20–50% enhancement in switching voltage changes and spontaneous emission efficiency, respectively.
Hydrogen and Oxygen Plasma Effects on Undoped and n–p Compensation-doped Single- and Multilayer Polycrystalline Silicon Resistor Films
Authors: Liou Bor Wen , Chang Shu Cheng , Wang Shui Jinn
Published: July 2005

In this study, we investigate hydrogen and oxygen plasma effects on undoped and n–p compensation-doped polycrystalline silicon (poly-Si) resistors. The current–voltage (I–V) characteristics, channel resistance (R
p), contact region resistance (R
j), total resistance (R
T=R
p+R
j), and activation energy of the poly-Si resistors with different film lengths and passivation layers were measured and analyzed. It is found that the film resistance has been strongly enhanced by either hydrogen or oxygen plasma treatments, which is attributed to the neutralization effect of plasma treatment inside the grain being overridden by the passivation effect at the grain boundary. Moreover, it is seen that both the total resistance and activation energy of undoped intrinsic films are larger than those of n–p compensation-doped films. To realize a high-value poly-Si resistor, a novel multilayer structure is proposed for the first time. Compared with the conventional single-layer structure, it is seen that the relatively smaller grain size in a four-layer structure results in an approximately 25–50% increase in resistance.
Double-Slit Interference Observation of Hot Electrons in Semiconductors–Analysis of Experimental Data–
Authors: Furuya Kazuhito , Ninomiya Yasunori , Machida Nobuya , Miyamoto Yasuyuki
Published: July 2005

This is a detailed description of the first definite observation of the double-slit interference of a hot electron in a solid. The observation has been achieved by fabricating a double-slit with a 12 nm opening and a 25 nm center-to-center distance and a detection electrode with a 40 nm width. Various inspections are made theoretically to confirm the double-slit diffraction/interference. This achievement will open the door to the creation of solid-state devices with new functions based on the wave nature of electrons.
Reoxidation Behavior of High-Nitrogen Oxynitride Films after O2 and N2O Treatment
Authors: Lin Bo Chun , Chang Kow Ming , Lai Chiung Hui , Hsieh Kuang Yeu , Yao June Min
Published: July 2005

Reoxidation of a high-nitrogen ultrathin oxynitride (∼1.3 nm) has been studied. The reoxidation is conducted using an alternation of nitrous oxide and oxygen gas in rapid thermal oxidation (RTO). The new finding in this study is the zig-zag characteristic of the oxidation rate by O2 and N2O. It is clear that the N2O oxidation rate is almost independent of the concentration of nitrogen in oxynitride through out the rapid thermal oxidation process, but the O2 oxidation rate is not.
Fabrication of Sr-Ferrite Plastic-Bonded Magnet Rotor by Injection Molding
Authors: Matsuyama Yoshihiko
Published: July 2005

A plastic-bonded strontium-ferrite rotor assembly for brushless dc motors is fabricated by injection molding to produce a four-pole arrangement of anisotropic SrO·6Fe2O3 plastic-bonded magnets. The resultant rotor has superior magnetic flux density characteristics to a conventional four-pole plastic-bonded rotor. The degree of anisotropy and hence magnetic flux of the magnets is found to be dependent on the injection time, with faster injection times producing magnets with higher flux densities. The proposed fabrication method and rotor design eliminate the need for a magnetic path and dynamic balancing of the rotor. The resultant motor therefore operates at a significantly lower noise level compared to motors based on conventional rotors.
Surface Texturing for Wafer-Bonded Vertical-Type GaN/Mirror/Si Light-Emitting Diodes
Authors: Huang Shao-Hua , Horng Ray-Hua , Hsu Shun-Cheng , Chen Tsung-Yu , Wuu Dong-Sing
Published: July 2005

An n-side-up GaN/mirror(Pd/Au)/Si light-emitting diode (LED) with surface texturing has been fabricated by a combination of wafer-bonding, laser lift-off, and surface texturing techniques. Two concentrations of KOH solution were used to roughen the n-GaN surface. In order to obtain a uniformly roughened surface, the solution was heated instead of being subjected to photoirradiation. The GaN/Pd/Au/Si LEDs with surface texturing exhibited a maximum luminance intensity of 130 mcd (at 20 mA) with a forward voltage of 3.2 V. The luminance intensity is over two times larger than that of the original planar GaN/sapphire LEDs (at 20 mA). Under high current injection, the surface textured GaN/Pd/Au/Si LEDs also showed a more stable luminance intensity. This feature is attributed to the Si substrate providing a good heat sink and surface roughening enhancing the external quantum efficiency. Furthermore, the n-side-up GaN/mirror(Pd/Au)/Si LEDs with surface texturing have been demonstrated to have high reliability.
Electron Microscopy of La0.7Ca0.3MnO3
Authors: Arita Masashi , Hamada Kouichi , Okada Akira , Asano Hidefumi , Matsui Masaaki , Shibayama Tamaki
Published: July 2005

The appearance of forbidden reflections in the electron diffraction patterns of L0.7Ca0.3MnO3 was studied, which violates the Pnma symmetry reported so far in X-ray and neutron diffractometry studies. The forbidden reflections originate through the multiple diffraction process of a crystal slightly inclined from its zone axis. Under this diffraction condition, the corresponding superlattice contrasts in high resolution transmission electron microscopy images were reproduced in image simulations made without the assumption of symmetry reduction in the crystal.
Laser-Induced Crystallization in AgInSbTe Phase-Change Optical Disk
Authors: Chang Yem-Yeu , Chou Lih-Hsin
Published: July 2005

Laser-induced crystallization in the initialization and erasing processes of a AgInSbTe phase-change optical recording disk was studied. After laser initialization, a AgInSbTe film formed a metastable face-centered cubic (f.c.c.) phase. Both the high-resolution transmission electron microscopy (HRTEM) cross-sectional image and the static test results showed the difficulty of nucleation. At low linear velocities, i.e., CD 1X and CD 2X, several clusters formed in amorphous marks due to the low cooling rate and the longer reheating of the subsequently applied pulses. These clusters enhanced nucleation and the amorphous marks probably crystallized via the nucleation and grain growth mechanism in the erasing process. The degree of order in the amorphous marks decreased with linear velocity, and no clusters existed in the amorphous marks at CD 4X. Due to the difficulty of nucleation, the erasing process was predominated by the direct grain growth mechanism at high linear velocities.
Improvement of Photocatalytic Efficiency of TiO2 Thin Films Prepared by Pulsed Laser Deposition
Authors: Yoshida Tatsuro , Fukami Yuko , Okoshi Masayuki , Inoue Narumi
Published: July 2005

The photocatalytic efficiency of TiO2 thin films was improved by the deposition of clusters during pulsed laser deposition in an oxygen atmosphere. It was found that the oxygen pressure and the distance between the target and the substrate affected the number and size of clusters. The clusters deposited at the substrate temperature of 250°C and the oxygen pressure of 100–300 mTorr were anatase-type crystal. In the photocatalitic evaluation, the film deposition with anatase-type clusters showed a high efficiency.
Ultraviolet High-Spectral-Resolution Lidar with Fabry–Perot Filter for Accurate Measurement of Extinction and Lidar Ratio
Authors: Imaki Masaharu , Takegoshi Yoshihiro , Kobayashi Takao
Published: July 2005

An ultraviolet high-spectral-resolution lidar has been developed for measuring the optical parameters of aerosol and cloud such as extinction coefficient, volume backscatter coefficient, lidar ratio and laser beam transmittance. In this system, the Mie backscatter signal is transmitted by the Fabry–Perot filter in contrast to the atomic or molecular absorption filter in a conventional high-spectral-resolution lidar. Using an ultraviolet laser wavelength of 355 nm, a high-accuracy measurement of aerosol optical parameters has been realized for an atmosphere with a low aerosol concentration. This method does not require an assumption about the relationship between the extinction and backscatter coefficients of aerosol and cloud.
Diffraction Effect on High-Resolution Liquid-Crystal-on-Silicon Devices
Authors: Chiang Kuan-Hsu Fan , Chen Shu-Hsia , Wu Shin-Tson
Published: July 2005

We extend the beam propagation method to calculate light propagation in reflective liquid crystal displays. The effect of diffraction on the optical performance of high-resolution liquid-crystal-on-silicon devices is investigated. The light efficiencies are simulated with respect to the pixel pitch for the vertically aligned and finger-on-plane modes. Computer simulation results indicate that the effect of diffraction on these devices is significant.
Fabrication of Roughness-Improved Polymer Waveguides by UV Imprinting Technique
Authors: Kim Jin Tae , Choi Choon-Gi
Published: July 2005

Increased losses for the telecommunication wavelengths of 1.3 and 1.5 µm and detrimental residual slab waveguide generation make the thermoplastic polymer-based waveguide devices unsuitable for manufacturing optical modules. To overcome this, nearly zero slab polymer waveguides was fabricated in a thermosetting polymer using a UV imprinting technique. Through the sacrificial oxide removal of the silicon mold, the sidewall roughness of the imprinted convex waveguide decreased; consequently, propagation loss can decrease to a level as small as the material loss.
Phenomenological Theory of Morphotropic Phase Boundary with Monoclinic Phase in Solid-Solution Systems of Perovskite-Type Oxide Ferroelectrics
Authors: Iwata Makoto , Ishibashi Yoshihiro
Published: July 2005

The phase diagram with monoclinic phase near the morphotropic phase boundary (MPB) and the dielectric constant in a solid-solution system of perovskite-type ferroelectrics are discussed on the basis of the Landau–Devonshire-type free-energy function expressed in terms of polarization components. It is confirmed that the origin of the large dielectric response near the MPB can be attributed to the instability perpendicular to spontaneous polarization, called the “transversal instability”.
Temperature Dependence of Magnetic Moment Orientation in Co2Z-Type Hexaferrite Estimated by High-Temperature Neutron Diffraction
Authors: Takada Yukio , Nakagawa Takashi , Fukuta Yasunari , Tokunaga Masatoshi , Yamamoto Takao A. , Tachibana Takeshi , Kawano Shinji , Igawa Naoki , Ishii Yoshinobu
Published: July 2005

We investigated the correlation between the thermomagnetic curve of Co2Z-type hexagonal barium ferrite and its magnetic moment direction. We measured the thermomagnetic curve of Ba3Co1.8Fe24.2O41, prepared using the conventional solid-state reaction method, in the temperature range from 294 to 773 K with a vibrating sample magnetometer under 70 Oe. The curve shows two significant magnetization slumps at 540 K and 680 K. High-temperature XRD patterns show that no crystal transformation occurs in the temperature region from 294 to 773 K. High-temperature neutron diffraction experiments were performed to investigate the magnetic moment orientation at elevated temperatures. The Rietveld analyses of the neutron diffraction patterns indicate that the temperature rise from 523 to 573 K makes the magnetic moments turn to the c-axis from a direction parallel to the c-plane most significantly. The slump in magnetization at 540 K may be attributed to the change in easy magnetization direction from the c-plane to the c-axis. The change in average orientation of the magnetic moments must be induced by the disappearance of the contribution of cobalt to magnetism in this temperature range.
Analysis of Acoustic Streaming in Nematic Liquid-Crystal Cell
Authors: Toda Kohji , Inoue Masaru , Moritake Hiroshi , Yoshino Katsumi
Published: July 2005

A periodic domain pattern induced in a nematic liquid-crystal cell under elastic wave propagation is investigated as a wave-propagation problem. An acoustic stream is generated under elastic wave propagation in a nematic liquid-crystal cell sandwiched between two glass plates. Numerical analysis is performed, taking into account the directional dependence of the viscosity coefficient of the nematic liquid crystal. The periodicity of the velocity field of acoustic streaming is recognized to be due to a periodic striped domain structure in the liquid-crystal cell. The periodicity of the striped domains observed in the liquid-crystal cell is related to the frequency of the elastic wave. The numerically analyzed frequency dependence of the periodicity of the striped domains is in good agreement with the observed results.
Calculation on Empirical Model of Chemical Properties of Phosphate Glass for MOS Capacitor
Authors: Okude Shin'ichiro
Published: July 2005

The frontier-electron theory based on extended Hückel calculation is applied to a ring cluster molecule to model a hygroscopic reaction in phosphate glass. It is shown that H+ rather than OH- plays a more important role in the reaction.
Analysis of Improved Transmittance in Fringe-Field Switching Mode Using Positive Liquid Crystal Incorporated with Chiral Dopant
Authors: Park Jun Baek , Kim Hyang Yul , Kim Kwi Hyun , Kim Seo Yun , Lim Young Jin
Published: July 2005

We studied transmittance in fringe-field switching mode using positive liquid crystal with added chiral dopant. When a chiral dopant (the pitch orientation of whose is in the same direction as the dielectric torque N) is added, the transmittances at the center and near the edge of the structure increase owing to the increase in each average twist angle toward the optimal twist angle.
Two-Beam X-Ray Holography Using Prism Optics
Authors: Takeuchi Akihisa , Suzuki Yoshio
Published: July 2005

Two-beam X-ray holography has been developed. A prism made of acrylic resin is used as a beam deflector for a hard X-ray wavefront dividing interferometer. The holographic imaging using this configuration is the same as that of the Leith-Upatnieks-type two-beam holography in the visible light region. Two-parallel-beam holography using a synchrotron radiation light source is performed. Two-spherical-wave holography using a focused beam with a Fresnel zone plate optics is also carried out in order to improve the spatial resolution. Measured holograms are numerically reconstructed. The spatial resolution of the two-spherical-wave holography system is found to be approximately 1 µm.
Area Expansivity Moduli of Regenerating Plant Protoplast Cell Walls Exposed to Shear Flows
Authors: Fujimura Yuu , Iino Masaaki , Watanabe Ugai
Published: July 2005

To control the elasticity of the plant cell wall, protoplasts isolated from cultured Catharanthus roseus cells were regenerated in shear flows of 115 s-1 (high shear) and 19.2 s-1 (low shear, as a control). The surface area expansivity modulus and the surface breaking strength of these regenerating protoplasts were measured by a micropipette aspiration technique. Cell wall synthesis was also measured using a cell wall-specific fluorescent dye. High shear exposure for 3 h doubled both the surface area modulus and breaking strength observed under low shear, significantly decreased cell wall synthesis, and roughly quadrupled the moduli of the cell wall. Based on the cell wall synthesis data, we estimated the three-dimensional modulus of the cell wall to be 4.1±1.2 GPa for the high shear, and 0.35±0.2 GPa for the low shear condition, using the surface area expansivity modulus divided by the cell wall thickness, which is identical with the Young's modulus divided by 2(1-σ), where σ is Poisson's ratio. We concluded that high shear exposure considerably strengthens the newly synthesized cell wall.
Pickup for Small Form Factor Optical Drive with 2.3 mm Height Actuator
Authors: Cheong Young Min , Lee Jin Won , Kim Kwang , Kim Sung Soo , Choi Jong Chul , Chung Chong Sam , Park In Sik
Published: July 2005

Recently, with the requirements of several mobile products coming to the fore, to cope with the market needs, various mobile storage applications have been developed. Moreover, the core components and technologies for mobile optical disc drives have been under continuous development. In the case of optical storage, a small optical pickup is required to realize a mobile optical disc drive, because the optical parts and an actuator are the main factors determining the optical pickup height. In this paper, we examine the 5-mm-high mobile small form factor optical (SFO) drive and achieve a good readout signal with 6.8% jitter using a limit equalizer. In addition, the use of 2.3-mm-high actuator with a horizontally arranged magnetic circuit for the mobile pick up reduces the height of optical pickup, and leads to high DC and AC sensitivity for low power consumption.
Blu-ray Disc Pickup Head for Dual Layer
Authors: Kim Tae Kyung , Ahn Young Man , Kim Seok Jung , Heor Tae Youn , Chung Chong Sam , Park In Sik
Published: July 2005

For dual-layer Blu-ray disc (BD) recording systems, the compensation of thickness differences is required. In addition the influence from the other layer should be considered. As a spherical compensation method, we have adopted a liquid crystal panel to fabricate a compact pickup head. Furthermore we have inserted a polarization diffractive optical element to reduce the influence from the other layer. In this paper, we report the readout test results of a dual-layer disc using a compact optical head.
Single Objective Lens with Numerical Aperture of 0.95
Authors: Itonaga Makoto , Ito Fumihiko , Saito Ryo , Saito Toshiya , Ohira Takuji , Yokochi Yoshinari
Published: July 2005

In this article, we describe the results of the development on an objective lens with a numerical aperture of 0.95. Manufacturing tolerance becomes the first issue for the realization of such lens. Measurement methods for the lens are also discussed in the article. The lens developed shows diffraction-limited performance. The lens is also installed in an optical pickup and analyzed in read-back experiments. The result confirms a superior modulation transfer function of the lens.
Optical Disk Recorder (ODR) for Satellite Use
Authors: Tanaka Kunimaro , Itoh Osamu , Iwai Hitoshi , Kasuya Masahiro
Published: July 2005

An earth-observing satellite flies at an altitude of 800 km. The data acquired while the satellite flies at the opposite side of the earth from a telemetry station has to be stored in the satellite because it is difficult to establish a communication channel between the telemetry station and the satellite. The use of the first optical disk recorder (ODR) in space has been planned [H. Anegawa, T. Fukuda, S. Yamamoto, D. Maeusli and M. Kasuya: Proc. Int. Symp. Optical Memory '91, (1991) p. 115; H. Anegawa, K. Tanaka and N. Tsuya: Proc. Optical Data Storage '92 p. 1 MD4 (1992)]. To make the optical disk drive work in space, the following measure was taken. The large acceleration during launching was solved using the launch lock mechanism. The temperature control mechanism was used to cope with a wide temperature change. Optical components were carefully selected for cosmic ray. ADEOS-II at which the ODR was installed was launched on December 14, 2002. The ODR had worked correctly for about ten months until the solar cell of the satellite stopped functioning. It was proved that the optical disk drive can work in space when an appropriate measure is taken.
Master and Slave Beam Servo Technique for Volumetric Bit-Wise Optical Data Storage
Authors: Park Sang-Ki , Milster Tom D. , Miller Tim M. , Butz John , Bletscher Warren
Published: July 2005

A master and slave servo technique that maintains tracking and focus registration inside a volumetric disk is presented, and the misregistration of the slave beam with respect to the master beam due to disk tilt and beam skew is calculated.
A New 9-Level Run-Length-Limited (1, 3) Code for Multilevel Optical Recording Channels
Authors: Lee Joohyun , Hong Youpyo , Lee Jaejin
Published: July 2005

In this paper, we propose the M=9 run-length-limited (d,k)=(1,3) code for multilevel recording channels. The code rate is 5/3 (bits/symbol), and the code has a simple 3-state encoder and a sliding block decoder. During the decoding process, the maximum error propagation of input data is seven bits. The structures of the encoder and decoder of the proposed code are very simple, so it may be easily implemented for high-density multilevel recording systems.
TeOX-Based Film for Heat-Mode Inorganic Photoresist Mastering
Authors: Ito Eiichi , Kawaguchi Yuko , Tomiyama Morio , Abe Shinya , Ohno Eiji
Published: July 2005

A TeOX-based inorganic photoresist was developed for mastering utilizing heat-mode recording. We discovered that the novel organic thermal isolation film markedly improved the patterning resolution of phase change mastering. We demonstrated Blu-ray Disc read only memory (ROM) mastering with a blue laser diode, using the TeOX-based photoresist and the thermal isolation film. The jitter values of a replicated disc were less than 6% at the full range of the disc. It was also proven that the mastering system is capable of recording 80 nm L/S. In addition, the mechanism of development was clarified.