bluuebunny/crossref_metadata_2025 huggingface dataset:
Percutaneous Ultrasound-guided Central Venous Catheters: The Lateral In-plane Technique for Internal Jugular Vein Access
Authors: Rossi Umberto G. , Rigamonti Paolo , Tichà Vladimira , Zoffoli Elena , Giordano Antonino , Gallieni Maurizio , Cariati Maurizio
Published: March 2014

Purpose

To describe the possible ultrasound guidance techniques for the insertion of central venous catheters (CVCs), with emphasis particularly to the lateral short axis in-plane technique.

Methods

Numerous articles have shown significant benefits of using ultrasound guidance for venous access. Two main approaches to vein puncture are available, when considering visualization of the needle during its entry into the vein under the ultrasound beam: in-plane and out-of-plane, which can be combined with two types of vein visualization, placing the ultrasound probe on the vein long axis or short axis.

Results

Advantages and limitations in internal jugular vein (IJV) cannulation for long-term dialysis CVCs are described for the above-mentioned approaches and visualizations. The lateral short axis in-plane technique has virtually no limitations, ensuring most benefits.

Conclusions

The lateral short axis in-plane technique should be considered the first-line technique for IJV cannulation.
Inactivation of Escherichia coli and Staphyloccocus aureus in Litchi Juice by Dimethyl Dicarbonate (DMDC) Combined With Nisin
Authors: Yu Yuanshan , Xu Yujuan , Wu Jijun , Xiao Gengsheng , Wen Jing , Chen Yulong , Zhang Yousheng
Published: March 2014

Inactivation of Gram-negative Escherichia coli and Gram-positive Staphyloccocus aureus in litchi juice by DMDC combined with nisin was individually investigated. A 1.66 log cycles reduction of E. coli and 2.03 log cycles reduction of S. aureus in litchi juice (pH 4.5) added without nisin was achieved as exposed to 150 mg/l DMDC at 30 °C for 1 h, and the inactivation rate of E. coli and S. aureus during initial 1 h was far greater than during the remaining 5 h. As exposed to 150 mg/l DMDC at 30 °C for 1 h, the inactivation of E. coli and S. aureus in the litchi juice showed a trend toward increase with increasing of nisin addition level in the range from 0 to 200 IU/ml. Moreover, DMDC and nisin exhibited a synergistic effect on the inactivation of E. coli and S. aureus in litchi juice, and the inactivation of E. coli and S. aureus in the litchi juice also depends on the temperature of litchi juice, pH value of litchi juice and DMDC concentration when treated with DMDC and nisin. In addition, E. coli showed higher resistance to nisin as comparing with S. aureus. After E. coli and S. aureus in the litchi juice of pH 4.0 were individually treated with 150 mg/l DMDC combined with 200 IU/ml nisin at 30 °C for 1 h, a complete inactivation of S. aureus (6.59 log cycles) was achieved, but only 3.52 log cycles reduction of E. coli was observed.
Impact of Chronic Obstructive Pulmonary Disease (COPD) on Patient’s Life and His Family
Authors: Kupryś-Lipińska Izabela , Kuna Piotr
Published: March 2014

Introduction: Chronic Obstructive Pulmonary Disease (COPD) is one of the most common chronic diseases of adults and is a major cause of chronic morbidity and mortality throughout the world. It is the cause of physical and mental suffering for the patient, significantly impairs quality of life, reduces the vital activity and affects the patient’s life in its various aspects. In 2012, the nationwide survey was conducted in COPD outpatients with a history of smoking exploring the various factors of the disease and its effects on the health and life of the patient. The purpose of the analysis presented here is to assess the impact of COPD and tobacco smoking on the patient’s health and life. Material and Methods: Data were collected from patients by their physicians during routine visit with usage of specifically prepared questionnaire for this study. Patients over 35 years of age, with diagnosed COPD, current or past smokers were recruited from outpatients settings. The study involved 10,365 patients with COPD. Representative sample of 2967 questionnaires were randomly drawn for the statistical analysis. Results: The mean age of responders was 61.15 ± 10.25 years, 33.98% of participants were women, 56.73% were current smokers and 43.37% declared smoking in the past. The largest number of patients had COPD in a moderate degree (II—acc. to GOLD 2010)—55.38%, sequentially mild (I)—21.40%, and severe (III)—19.96%, the smallest group were people with very severe degree of disease (IV)—3.27%. Using the new classification of the COPD severity (acc. to GOLD 2013), the largest group of patients were less symptomatic (mMRC ) subjects who had a low risk (A)—52.67%, but in fact a second group of patients were subjects with severe symptoms and a high risk (D)—20.45% , sequentially—patients with low severity of symptoms, but a high risk (C)—16.16% , and severe symptoms and a low risk—10.72% (B). Patients most often reported that COPD affects their activity in sport (83.45% of respondents), than in living activity (82.78%) and family life (79.3%). COPD had significant (moderate or severe) effect on sport (60.85%) and life activity (38.44%), as well as on work (34.9%), but the greatest impact, leading up to the resignation of the activity: on sport practice (21.75%), sexual intercourse (12.6%) and hobbies (11.49%). The disease severity (GOLD 2013 C/D) was the independent factor which reduced all forms of activity. In patients’ opinion smoking had negative impact on their health (52,65%) and the family budget (41.83%). The negative impact of smoking on family relations was declared by 16.38% of respondents. Among the factors which favor effective quit from addiction were: age ≥ 65 years and more seere degree of obturation (III/IV GOLD 2010). Conclusions: The results of the study confirmed the significant impact of the disease and addiction to smoking not only on patients’ life but also on their families.
p53 activity is selectively licensed in the Drosophila stem cell compartment
Authors: Wylie Annika , Lu Wan-Jin , D’Brot Alejandro , Buszczak Michael , Abrams John M
Published: March 2014

Oncogenic stress provokes tumor suppression by p53 but the extent to which this regulatory axis is conserved remains unknown. Using a biosensor to visualize p53 action, we find that Drosophila p53 is selectively active in gonadal stem cells after exposure to stressors that destabilize the genome. Similar p53 activity occurred in hyperplastic growths that were triggered either by the RasV12 oncoprotein or by failed differentiation programs. In a model of transient sterility, p53 was required for the recovery of fertility after stress, and entry into the cell cycle was delayed in p53- stem cells. Together, these observations establish that the stem cell compartment of the Drosophila germline is selectively licensed for stress-induced activation of the p53 regulatory network. Furthermore, the findings uncover ancestral links between p53 and aberrant proliferation that are independent of DNA breaks and predate evolution of the ARF/Mdm2 axis.
Intestinal epithelium-derived BMP controls stem cell self-renewal in Drosophila adult midgut
Authors: Tian Aiguo , Jiang Jin
Published: March 2014

Stem cells are maintained in a specialized microenvironment called niche but the nature of stem cell niche remains poorly defined in many systems. Here we demonstrate that intestinal epithelium-derived BMP serves as a niche signal for intestinal stem cell (ISC) self-renewal in Drosophila adult midgut. We find that BMP signaling is asymmetric between ISC and its differentiated daughter cell. Two BMP ligands, Dpp and Gbb, are produced by enterocytes and act in conjunction to promote ISC self-renewal by antagonizing Notch signaling. Furthermore, the basement membrane-associated type IV collagens regulate ISC self-renewal by confining higher BMP signaling to ISCs. The employment of gut epithelia as a niche for stem cell self-renewal may provide a mechanism for direct communication between the niche and the environment, allowing niche signal production and stem cell number to be fine-tuned in response to various physiological and pathological stimuli.
Structural and dynamical properties of the junction between a single carbon nanotube and a graphene nanoribbon
Authors: Yoshimoto Masatoshi , Mochiji Kozo , Moritani Kousuke , Inui Norio
Published: March 2014

Using molecular dynamics (MD) simulation, we consider the stable structure of a partially unzipped carbon nanotube, in which a graphene nanoribbon is formed at the tip. We characterize the shape of the junction between a single carbon nanotube and a graphene nanoribbon using three parameters: the radius of curvature, bend, and twist-rotation. The increase in the radius of curvature is proportional to the square of the distance from the boundary between the carbon nanotube and the graphene nanoribbon, and this can be explained by using continuous mechanics for a thin plate. The oscillations of the graphene nanoribbon at room temperature are also taken into consideration.
Anodization of Silicon in RF Induced Oxygen Plasma
Authors: Ho Vu Quoc , Sugano Takuo
Published: March 2014

Silicon dioxide films were grown on Si substrates by anodization in RF induced oxygen plasma at the pressure of 0.2 Torr and temperature of 600°C. SiO2 films of 1 µm in thickness were obtained within one hour. The selective oxidation was studied and Al2O3 was found to be effective in masking against the oxidation. The bird's beak shaped structure was greatly reduced.
Resistivity Reduction of Polycrystalline Silicon Film by Laser Annealing
Authors: Onga Shinji , Kohyama Susumu , Shibata Kenji , Nagakubo Yoshihide , Iizuka Hisakazu
Published: March 2014

Utilizing a laser annealing technology, a drastic reduction in polysilicon sheet resistivity has been observed. The technology was successfully applied in MOS fabrication process steps, and practically no degradation in device characteristics was observed.
Physical mechanism of polysilicon laser annealing is also presented, through a study of crystalline structure, mobility and carrier concentration, and the thermal instability during the subsequent thermal annealing.
Improvement in Electrical Properties of Laser Annealed Ion Implanted GaAs
Authors: Badawi M. H. , Sealy B. J. , Stephens K. G. , Akintunde J. A.
Published: March 2014

GaAs samples implanted at room temperature with selenium ions at energies in the range 100–800 keV were annealed with a Q-switched ruby laser. The annealing was carried out in air, with no protective layer on the GaAs samples. The percentage electrical activity was found to depend on the implanted dose, ion energy, laser energy density and the substrate temperature during laser annealing. The mobilities of the electrically activated atoms were generally lower than the expected values. However, these were found to increase when the samples were thermally annealed subsequent to the laser irradiation. Low dose implants, i.e. less than 1.1014 cm-2, previously shown to be insensitive to laser annealing, have been successfully annealed in this work when the substrates were held at 200°C during laser annealing.
(Invited) Basic Technology for VLSI
Authors: Tarui Yasuo
Published: March 2014

This paper describes some of the results of recent work in the fields of microfabrication technology and crystal technology at the VLSI Cooperative Laboratories. Concerning microfabrication technology, three types of EB pattern delineators are described, along with a pair of step and repeat UV projection systems, and a 1:1 deep UV scanning projection system. Some of the results of research on EB projection, X-ray projection and EB resist are also described. Concerning crystal technology, research centering on crystal warpage, microdefects and their relations to impurities is discussed.
Dynamic Injection MNOS Memory Devices
Authors: Kondo Ryuji , Yatsuda Yuji , Koyanagi Mitsumasa , Itoh Yokichi
Published: March 2014

Dynamic Injection MNOS (DIMNOS) memory devices are proposed which feature high speed writing, 5 V drain voltage and a dynamic RAM with MNOS backup. These devices have one or two control gates and one MNOS memory between the control gates and field SiO2 layer.
In the above structures, the inversion layer under the MNOS gate is filled with charges transferred from the source through the control gates while writing voltage is being applied to MNOS gate. Then, the control gates are electrically closed and the stored charge in the inversion layer is injected into the interface between the thin SiO2 and Si3N4 layers in the MNOS.
In the experimental results, N-channel Si-gate DIMNOS memory devices are written as fully as conventional MNOS memories in less than 50 nanoseconds. Furthermore, in the dynamic inhibited writing mode, writing is indeed inhibited with pulse widths shorter than 1.0 msec if the number of inhibited writing attempts is kept to less than 103 by writing pulse shape improvement.
A New Multiplex Input Technique for High Density CCD Memory
Authors: Fujishima Kazuyasu , Yamada Michihiro , Tada Tetsuo , Takano Satoshi , Yoneda Masahiro , Gamou Yoshimi
Published: March 2014

A new multiplex input technique utilizing a charge splitting operation is proposed for high density CCD memory.
This technique permits effective arrangement of the high sensitivity sense amplifiers. As a result, the repeat spacing of the CCD shift registers becomes minimum value which is given only by the channel plus isolation width.
An all TTL compatible 64 K-bit CCD memory has been designed and fabricated to demonstrate this new technique.
Static Induction Transistor Logic
Authors: Nishizawa Jun-ichi , Nonaka Terumoto , Mochida Yasunori
Published: March 2014

The static induction transistor logic (SITL) equivalent to PL is evaluated by fabricating type D-F/F frequency divider and 14 bit BCD programmable counter to prove its potentiality in VLSI. SITI2L is also implemented into LSI.
The normally-configured SIT is introduced to serve as a driver transistor in the SITL having new circuit configuration in order to improve the speed performance, where output Schottky diodes are fabricated to ensure the decoupling between outputs. The performance of this Schottky SITL is evaluated in the ring oscillator, where the propagation delay is obtained 2.5 nsec at a power dissipation of 100 µW.
(Invited) X-Ray Lithography
Authors: Yamazaki Shin-ichi , Hayasaka Toa
Published: March 2014

An X-ray exposure system has been built aiming at 1 µm pattern replication, which will operated automatically. On the basis of X-ray attenuation analysis, Si–K radiation was chosen. A high power (more than 20 kW input) X-ray source has been equipped with a water cooled rotary target. For alignment, precise mask-wafer displacement detection by vibration method and precise three dimensional aligning mechanism have been adopted. Detection resolution less than ±0.1 µm and mechanism step resolution less than 0.01 µm have been obtained. Light transparent X-ray mask consisting of Si3N4 film has been developed and in use. Dry etching temperature has been lowered to 50°C, which permits the use of heat feeble, highly sensitive resists. The system has been adopted to the fabrication of various devices such as 1 µm magnetic bubble devices, MOS ring oscillator and so on.
Interface Effects on Drain Current Instability in GaAs MESFETs with Buffer Layer
Authors: Itoh Tomohiro , Yanai Hisayoshi
Published: March 2014

Interface effects on drain current instability in GaAs MESFETs with buffer layer were investigated by applying DLTS technique to the drain current transients. The measurements revealed that the instability is due to deep acceptors or hole traps, which exist at the interfaces and in the buffer layer and the semi-insulating substrate. Five kinds of deep levels were found for three groups of FETs. Particularly it was clarified that the long-term drift in the drain current is attributed to Cr in the buffer layer as well as in the semi-insulating substrate.
High-Brightness Green-Light-Emitting Thin-Film Electroluminescent Device
Authors: Okamoto Kenji , Hamakawa Yoshihiro
Published: March 2014

A high-brightness green-light-emitting thin-film electroluminescent (EL) device has been developed. The device has an In2O3–Y3O3–ZnS: TbF3–Y2O3–Al structure with a semiconductive Y2O3 layer instead of an insulating layer. A typical brightness and external power efficiency estimated are 200 fL and 2×10-2%, respectively at the excitation frequency of 5 KHz. These values are several times higher than those ever reported on green-light-emitting thin-film EL devices. A series of technical data on the performances of the developed EL device and experimental results for the characterization of carrier injection mechanism are presented. It is proposed that the semiconductive Y2O3 layer acts as not only a current limiter to protect ZnS layer providing with long life operation but also an efficient carrier injector to the ZnS.
(Invited) Mode Control in Semiconductor Lasers
Authors: Ito Ryoichi
Published: March 2014

The origins of mode instabilities in stripe-geometry semiconductor lasers are described. The principle of transverse mode stabilization and its embodiment in various laser structures are reviewed. Properly-designed lasers have been shown to oscillate in a single transverse and longitudinal mode without any kinks in the light-current characteristics over a wide range of output powers.
Degradation Characteristics of Ga1-xAlxAs Visible Diode Lasers
Authors: Kajimura Takashi , Kuroda Takao , Yamashita Shigeo , Todokoro Hideo , Nakamura Michiharu , Umeda Jun-ichi
Published: March 2014

A marked dependence of life on lasing wavelength is found in Ga1-x
Al
x
As visible lasers. The lasers degrade faster for shorter lasing wavelengths. Degradation in the wavelength region below 730 nm can be mainly attributed to the rapid formation of macroscopic defects in the active region. A notable improvement in life is obtained for these shorter wavelength lasers by Te-doping of the active layer. On the other hand, enhanced facet oxidation is the main degradation mechanism in lasers operating above 740 nm. Facet coatings using SiO2 films effectively suppress facet oxidation. As a result, room temperature extrapolated lives exceeding 10000 hours are achieved by facet coated lasers operating at wavelengths above 740 nm.
Slow Degradation Mechanism of GaAlAs Light-Emitting Diodes
Authors: Kondo Kazuo , Yamakoshi Shigenobu , Isozumi Shoji , Yamaoka Toyoshi
Published: March 2014

The slow degradation of GaAlAs LEDs in accelerated aging has been studied by the capacitance spectroscopy method. We observed a drastic increase in the density of two deep levels A and B in the active layer during a homogeneous degradation of the LEDs. The deep levels A and B are hole traps with activation energies of 0.43 eV and 0.76 eV, respectively, and they are commonly observed in LPE GaAlAs. An increase in the cutoff frequency of the LEDs (-1.5 dB point in light output) during aging was also observed. An explicit correlation between the density of these levels and the cutoff frequency was shown with the homogeneous degradation of the LEDs, which shows a possibility that the deep levels in the active region contribute to the slow degradation of GaAlAs LEDs. The degraded LEDs were examined in the transmission electron microscope. No images of defect structures over 100 Å dia. were found in any part of the active region.
Efficient Solar Cells from Metallurgical-Grade Silicon
Authors: Warabisako Terunori , Saitoh Tadashi , Kuroda Ekyo , Itoh Haruo , Nakamura Nobuo , Tokuyama Takashi
Published: March 2014

In order to examine the possibility of utilizing metallurgical-grade silicon (MG-Si) for terrestrial photovoltaic use, solar cells are fabricated either by epitaxial growth or by direct diffusion on a substrate which is obtained by Czochralski crystallization conducted once or twice.
Even by single crystallization of this material it is possible to obtain 10% efficiency if a 50 µm active layer is grown on the substrate crystal. A 10.5% (11.9% on the active area) cell is realized for the case where this material is subjected to acid-leaching prior to crystallization. A conversion efficiency as high as 8.5% is obtained for a directly diffused cell when a proper gettering process is applied.
High-Efficiency GaAs MOS Solar Cells by Anodization in Active Region
Authors: Hasegawa Hideki , Tamori Shinichi , Sawada Takayuki
Published: March 2014

Anodization of GaAs in various modes is investigated for possible application to MOS solar cells. It is found that anodization in active region using AGW electrolyte is very effective for increasing the open-circuit cell voltage, giving reproducibly 0.7–0.8 V. On the other hand, anodization in the passive region leads to an anomalous cell characteristic with much reduced photocurrents. The mechanism causing the difference is explained in terms of electrochemical control of the composition of surface oxide layer on the basis of detailed electrical and AES analyses.
Electrical Characterization of Micro Defects in Silicon Crystal
Authors: Ikuta Kenji , Matsuoka Yutaka , Takaoka Hidetoshi
Published: March 2014

Effect of crystalline defects on minority carrier lifetime in silicon is investigated with regard to oxygen concentration and annealing conditions. Various defects have been introduced during two-step annealing in wafers sliced from several positions in Czoch-ralski silicon ingot. For each wafer, lifetime was measured by the photo-conductive decay method. Defects were analyzed by transmission electron microscopy. Lifetime and defect generation show plain dependence on both crystal position (oxygen concentration) and annealing conditions. Lifetime is found to be inversely proportional to the cube root of stacking fault volume density. Contributions from microdefects other than stacking faults were found.
Silicon Epitaxy by Plasma Dissociation of Silane
Authors: Suzuki Setsu , Takai Hiroshi , Okuda Hidekazu , Itoh Tadatsugu
Published: March 2014

A plasma epitaxy system has been designed to realize low temperature epitaxial growth of silicon. In this system control on the silane dissociation rate and the silicon deposition rate is done separately with the aid of RF glow discharge. Investigations by RBS, TED and TEM techniques proved that layers grown by this method at as low as 700°C kept good crystalline quality. Electrical measurements have been also carried out and revealed that the electrical properties of the layers grown at 750°C were equivalent
to those of bulk silicon.
Computer Aided Si-MOSFET Process Designing
Authors: Ohno Yasuo , Okuto Yuji
Published: March 2014

A computer program is developed, which simulates Si-MOSFET fabrication process and its electrical characteristics. In this program,one dimensional impurity distribution and oxide thickness are traced and Poisson's equations with Maxwell-Boltzmann distribution function are solved. Process designing for an n-channel Si-gate E/D MOSIC is carried out. The predictions are in good agreement with the experimental results. Various process sensitivities can be estimated using this program. This program will be useful for process, device and circuit designing of MOSIC's.
Tunable Surface-Acoustic-Wave Generator on a Monolithic MIS Structure
Authors: Tsubouchi Kazuo , Minagawa Shoichi , Okamoto Takeshi , Mikoshiba Nobuo
Published: March 2014

Experimental results are reported on the frequency spectrum, the conversion efficiency, and the tunability of the center frequency of the Rayleigh-wave parametric generator on an n-Si/SiO2/ZnO/Al structure which we have recently proposed. It was found that this device can be used as a really tunable, wide-band center-frequency, and high Q generator of surface acoustic waves without micro-fabrication. Experimental results on the generator of the first higher-order Rayleigh mode (the Sezawa mode) are also reported. It was found that the threshold pumping power is smaller than that of the
Rayleigh mode and is in fairly good agreement with the theoretical estimation.
(Invited) Physical Effects in Small Geometry MOS Transistors
Authors: Moll John L. , Sun Edward Y.
Published: March 2014

Many of the characteristics of small geometry MOS transistors depend on the channel length, the channel width and the impurity profile. In this paper, we will describe the small geometry effect in terms of the charge sharing effect and the velocity saturation effect which result in the change in threshold voltage and the change in the intrinsic capacitance. The non-uniform doping which results in an increase in the ideality factor in the subthreshold region at short channel length will also be described. In addition, the maximum voltage limitation of the small geometry MOS devices due to punch through, avalanche, bipolar breakdown, electron injection into the gate oxide and the gate oxide breakdown will also be described.
Amorphous Si: H Heteroface Photovoltaic Cells Based Upon p-i-n Junction Structure
Authors: Nitta Yoshiteru , Okamoto Hiroaki , Fujita Nobuhiko , Hamakawa Yoshihiro
Published: March 2014

Utilizing the eminent electronic properties of amorphous hydrogenated silicon, heteroface photovoltaic cells based upon p-i-n junction structure have been designed and fabricated. The cell parameters in a single p-i-n heteroface junction cell have been determined experimentally, and a cell having a conversion efficiency of 4.5% was obtained. The cell efficiency is, through a simple analysis, expected to increase up to 7%. While,as one of the extended cell structures to improve the efficiency, multijunction cells have been proposed. At the present stage of the experiments, the efficiencies of around 4% with the open circuit voltage almost proportional to the number of the p-i-n junction units were realized in the multi-junction cells which had optimized cell parameters. Further improvement of the cell efficiency in these cell structures based upon p-i-n junction should be essentially accompanied by that of film quality of amorphous silicon.
Photoelectric Properties of n-ZnSe/p-Si or p+ -GaAs Heterojunctions
Authors: Kurita Shoichi , Suda Toshikazu , Yajima Hiromi , Takagi Atsuo , Tanaka Ryutaro
Published: March 2014

Resistivity as low as ∼0.1 Ωcm has been obtained in ZnSe which has been evaporated onto p-Si and p+ -GaAs. Infrared quenching of the photocapacitance technique has been applied on these samples to obtain the deep level information. The spectrum of the photoionization cross section for holes from Ag(Zn) level to the valence band was obtained and the peak value was 4.2×10-16 cm2 in n-ZnSe/p+GaAs. The deep Ag(Zn) level is located at 0.59 eV from the top of the valence band at 300 K. Two levels of 0.6 and 0.9 eV from the top of the valence band are obtained in the undoped n-ZnSe/p-Si at 300 K. The dominant current transport mechanism is tunneling-recombination via interface states. The doping profile of the Ag(Zn) level was also obtained from the modified C-V method.
Plasma-Assisted Deposition of GaAs Thin Films
Authors: Takenaka Kazuhiro , Hariu Takashi , Shibata Yukio
Published: March 2014

Amorphous and crystalline GaAs thin films have been successfully deposited by plasmaassisted deposition, in which evaporated Ga and As atoms react in discharging plasma to condense on substrates. Orientations of the crystalline films deposited at substrate temperatures above 350°C depended upon the structural properties of substrates and they grew epitaxially on GaAs and Ge wafers. Although non-doped films all showed p-type conduction, n-type films are controllably deposited by doping Sn which was supplied as SnCl4 mixed in argon gas.
Performance of Circular Fresnel Lens Photovoltaic Concentrator
Authors: Nakata Yukihiko , Shibuya Noriaki , Kobe Takashi , Okamoto Koji , Suzuki Akio , Tsuji Takateru
Published: March 2014

A 300 W polar axis tracking concentrator with 36 circular Fresnel lenses and cells has been fabricated. Commercial Fresnel lenses are not sufficient for a concentrator, because the cell efficiency is reduced by their non-uniform light distribution. Therefore, a 40×40 cm circular Fresnel lens was designed to obtain the uniform light distribution. As a result of this improvement, the output power becomes about 50% greater than that of the commercial lens. The optical efficiency of the lens is 83%. A 50 mm diameter silicon concentrator cell is n on p type with low bulk resistivity and has a fine radial grid. The output power from a typical concentrator cell is 9.13 W (I
sc=18.3 A, V
oc=0.666 V, FF=0.749) with 12.0% cell efficiency under 4.7 W/cm2 sunlight at 38°C. The output power from five concentrator units is 253.7 W (I
sc=20.6 A, V
oc=18.95 V, FF=0.65) with 10.2% total cell efficiency.
Combined Photovoltaic and Thermal Hybrid Collector
Authors: Suzuki Akio , Kitamura Susumu
Published: March 2014

Hybrid collector which produces both electric and thermal energy is very effective system for heightening efficiency of solar energy collector.
In order to obtain the fundamental characteristics of these systems, two liquid type flat plate thermal collectors with selective surface have been modified by attaching 3'' diameter silicon solar cells.
The measured cell array efficiencies were 8.84% and 9.20% at 28°C, AM 1.15. The maximum thermal efficiencies of these hybrid systems were 72% and 77% using water as coolant.
Electronic Band Structures of I-III-VI2 Compounds
Authors: Oguchi Tamio , Hamajima Toshiki , Kambara Takeshi , Gondaira Ken Ichiro
Published: March 2014

Electronic band structures of CuGaS2 and CuAlS2 are selfconsistently calculated by using the discrete variational Xα method and the results are compared with the optical data. The contents of the valence and core bands are reasonably coincident with the XPS mesurements. The top of the valence bands is an admixture state of Cu3d and S3 p orbitals. The crystal-field splitting of the uppermost valence band is about 0.2 eV. The fundamental energy gaps are direct transitions from \varGamma4 to \varGamma1.
Vibrational Properties of Off Diagonally Disordered CuInS2 Crystal
Authors: Joshi N. V.
Published: March 2014

Lattice dynamical behaviour of “Off Diagonal Partially Disordered CuInS2” has been investigated in the range of 10 cm-1 to 400 cm-1 at 4.2 K by using Fourier transform spectroscopy. All the vibrational modes corresponding to the chalcopyrite structure are found to be absent; however new modes corresponding to local structural excitations have shown their appearance in far infrared absorption spectrum. Number and positions of these metamorphic modes are critically examined using group theory and conventional F–G matrix. It has been found out that in “Off Diagonal Disordered System”; like in amorphous semiconductors; there exists a short range coherence length for the vibrational modes giving rise to a phonon spectrum of molecular structure based on constitutional short range order.
Transport Properties of Ternary Compounds
Authors: Wasim S. M. , Marcano G. , Porras G. S.
Published: March 2014

The Hall mobility, thermal conductivity and thermoelectric power of CuInTe2 and CuGaTe2 and the thermal conductivity and thermoelectric power of CuInSe2 between 80 K and room temperature have been studied. The temperature variation of the mobility has been explained by taking into account the scattering of the charge carriers by ionized and neutral impurities and due to the presence of the space charge defects. From the theoretical fit of the thermal conductivity data, the impurity concentration and the Gruneisen constant have been estimated. The density of states effective mass has been calculated from the Seebeck coefficient.
Lattice Vibrations in CdGa2S4
Authors: Yamamoto K. , Kasahara H. , Imasato I. , Abe K.
Published: March 2014

The far-infrared reflectance spectra of meltgrown single crystal CdGa2S4 have been measured at room temperature. Nine of ten reflectance spectra which were anticipated from the irreducible representation are observed for this material. These reflectance peaks are attributed to the reststrahlen bands due to the ionic bonds between the positive metal ions and negative chalcogen ions. From the reflectance spectra, the transverse and longitudinal optical phonon frequencies and the static dielectric constant are calculated. In this case, ωTO=84 cm-1, 134 cm-1, 166 cm-1, 239 cm-1, 265 cm-1, 310 cm-1, 319 cm-1, 342 cm-1 and 359 cm-1, ωLO=89 cm-1, 136 cm-1, 171 cm-1, 245 cm-1, 267 cm-1, 312 cm-1, 340 cm-1, 348 cm-1 and 384 cm-1, and ε
0=9.14 for CdGa2S4 single crystal.
On the Electronic Properties of Ordered Vacancy Compounds
Authors: Mackinnon A.
Published: March 2014

It is shown that some of the properties of ordered vacancy compounds can be understood in terms of a strong dependence of the highest valence bands on the positions of the anions. A pseudopotential calculation for Cd □ Ga2Se4 is presented in which special attention has been paid to the interaction of the band structure with the so called “breathing” mode, and which casts doubt on the meaningfulness in this case of the traditional division of energy gaps into direct and indirect.
Crystallographic Distortion and the Interpretation of the UPS Spectrum in α-CdIn2Se4
Authors: Baldereschi A. , Meloni F.
Published: March 2014

Band calculations by the empirical pseudopotential method for α-CdIn2Se4 show that some energy bands are rather sensitive to the position of atoms in the unit cell. In order to explain recent photoemission data we propose a structural distortion which preserves the space group symmetry of the ideal Vd
1 structure. The anions move away from the Cd atom and towards the two nearest In cations in agreement with simple chemical models. The crystallographic distortion is similar to those observed experimentally in many other ternary compounds and is explained by the presence in this material of two different chemical bonds and a periodic array of vacant cation sites.
Electronic Structure of Transition Metal Sulfospinels
Authors: Haas C.
Published: March 2014

The electrical transport properties and the magnetic properties of transition metal sulfo- and selenospinels are discussed in terms of simple qualitative energy level diagrams.
Photoelectron spectra give direct information on the relative position of transition metal d-bands and the chalcogen p-band. The absence of satellites in the photoelectron spectra of the Cu core levels in CuCr2S4 and in many other Cu containing chalcogenides shows that in all these compounds Cu is monovalent (3d
10). The small energy separation between Cr(3d) and S(3p) is responsible for longrange superexchange; a theory for long-range superexchange is briefly discussed.
The d-electrons in CuTi2S4 and CuV2S4 are itinerant, the d-electrons in CuCr2S4 are localized. The problem of the localization of d-electrons in transition metal chalcogenides is discussed in general. It is shown that the transition from localized to itinerant d-electrons is very subtle, and depends on details of composition and structure.
Photodetecting Properties of CuInSe2 Homojunctions
Authors: González J. , Rincón C. , Redondo A. , Negrete P.
Published: March 2014

We studied the photovoltaic properties of homojunctions prepared by indium diffusion on p-type CuInSe2 at liquid nitrogen and room temperatures. The CuInSe2 was grown by the Bridgman method.
We obtained the photovolatic spectra for both parallel and perpendicular incident lights with respect to the plane of the junciton (both on the p and n sides). The wavelength range was between 1.4 µm and 0.8 µm. We calculated a quantum efficiency of 40% at room temperature. This efficiency remained approximately constant between 1.2 µm and 0.9 µm.
We have also measured response times for the junction at 300K. For change of incident light the response time is 1.2×10-6 sec and for change of bias the response time is 4×10-7 sec.
Electric Conductivity and 3d-Electron Distribution in CuCr2Se4-xBrx
Authors: Yamaguchi Yasuo , Ohishi Yasutake , Ohashi Masayoshi , Yamashita Osamu , Watanabe Hiroshi
Published: March 2014

The unpaired electron distribution is measured for a single crystal of CuCr2Se4-x
Br
x
with x=0.5 by using polarized neutron diffraction technique. The values of the magnetic moments of µcr=2.77±0.07 µB and µCu=-0.07±0.01 µB are obtained. In comparison with the results obtained for the case of x=0.0, the additional electrons introduced by substitution of Se by Br are shown to occupy 3d-orbital of Cr. The radial distribution of 3d-electrons of Cr for x=0.5 is observed to be more contracted than that for x=0.0 in spite of the number of 3d-electron being larger for x=0.5 than x=0.0. This is considered to manifest an increase of the correlation energy of Cr, in conformity with decreasing electric conductivity.
Ultrasonic Attenuation and Elastic Behavior in Zero-Gap Semiconductor CdxHg1-xSe
Authors: Kumazaki Kenji
Published: March 2014

The ultrasonic attenuation and the sound velocity in Cd
x
Hg1-x
Se (0≦x<0.6) are measured by the pulse-echo method in the frequency range of 10 to 90 MHz at temperatures between 77 K and 298 K. The attenuation is not explained by the ordinary attenuation mechanisms, e.g., the Akhieser and the dislocation losses in HgSe (x=0). The main cause of the attenuation is probably affected by the inverted band structure rather than the lattice imperfections. The relation between the reduced elastic constants and the mole fraction of CdSe suggests that there is a phase transition in Cd
x
Hg1-x
Se at x=0.81. And the distribution of the Young's modulus is calculated in the (001) and (110) planes.
Heavy Metal Ternary Compounds for Infrared Acousto-Optic Applications
Authors: Feigelson R.
Published: March 2014

The major factors which influence the properties of infrared acousto-optic materials are discussed. To illustrate how a predictive methodology can be applied to the selection of potentially useful acousto-optic materials, a recent study concerned with the selection, synthesis and crystal preparation of compounds containing Tl, Bi and Te is described.
Preparation and Photovoltaic Properties of CdIn2S4/CuInSe2 Heterojunctions
Authors: Endo Saburo , Irie Taizo
Published: March 2014

N-CdIn2S4/p-CuInSe2 heterojunctions have been prepared by depositing CdIn2S4 films on p-type CuInSe2 single crystals. The current-voltage characteristics suggest that the tunnel-recombination process predominates in the mechanisms of passage of forward current through the heterojunctions. The capacitance-voltage characteristics of the diodes were those of an abrupt junction. An energy-band diagram for the heterojunctions is proposed. The photovoltaic properties obtained are an open-circuit voltage of 0.43 V, short-circuit current of 8.7 mA/cm2, fill factor of 0.46 and conversion efficiency of 2%. The photospectral response of the diodes, measured for light incident through the CdIn2S4 window, is fairly flat between 500 and 1200 nm. The quantum efficiency at 633 nm is 0.18.
Defect Properties of Some 1362 Chalcopyrite Compounds
Authors: Schwab C.
Published: March 2014

Some defects as naturally occuring in I-III-VI2 compounds are surveyed, with a particular emphasis on those identified by the direct method of electron paramagnetic resonance in two model compounds, namely CuGaS2 and AgGaS2.
Both extrinsic centres, linked to a transition metal contamination and intrinsic centres have been observed, whose behaviour is strongly dependent on physico-chemical treatments.
Finally, the relationships between these defects and some useful properties, which they might perturbate are examined, in pointing out their relevance with some current characterization problems of solid state material science.
(Invited) LPE and Characteristics of GaInAsP/InP 1.5 µm Region Laser Diodes
Authors: Nagai Haruo
Published: March 2014

InP/GaInAsP/InP DH structure crystals for 1.5–1.6 µm wavelength region have been grown by LPE. Difficulties due to dissolution of the quaternary active layer during the growth of the following InP layer are avoided by lowering the LPE temperature to near 600°C. This LPE technique has also been applied to the growth of buried-heterostructure crystals. Characteristics of planar stripe lasers and buried-heterostructure lasers (BH lasers) fabricated from these crystals are reported.
P-Column Gate Field Effect Transistor
Authors: Asai Kazuyoshi , Ishii Yasunobu , Kawasaki Yasuhiro , Kurumada Katsuhiko
Published: March 2014

Normally-off GaAs FETs with p-columns as the gate were fabricated. The transconductance exhibited considerably high value associated with relatively smaller sacrifice of the gate capacitance increase. The propagation delay of 145 ps/gate was observed from the ring oscillator made of 6 µm width devices with 2 µm column diameter dissipating 441 µW/gate.
Properties of a Fluorinated Heat-Resisting Amorphous-Silicon Containing No Hydrogen
Authors: Matsumura Hideki , Furukawa Seijiro
Published: March 2014

A fluorinated amorphous-silicon alloy (a-Si: F), whose dangling bonds are terminated only by fluorine, is produced by the radio frequency sputtering of silicon in mixtures of Ar and SiF4 gases. Both n- and p-type conductivity control of this a-Si: F is achieved by substitutional dopings of phosphorous and boron with the addition of BF3 and PF5 gas in the sputtering gas. Properties of a-Si: F, such as photo-conductivity and optical band gap, are measured before and after annealing process, and the structural properties of a-Si: F are also studied. It is found that the controllability of conductivity of this a-Si: F by n- and p-doping is comparable to that obtained for the sputtered hydrogenated a-Si, a-Si: F is heat-resistant up to annealing temperature of 600°C, and that a-Si: F has porous structures which may affect the value of photo-conductivity.
A Proposed Novel Amorphous-Silicon Image Sensor
Authors: Matsumura Masakiyo , Hayama Hiroshi , Nara Yasuo , Ishibashi Koichiro
Published: March 2014

A novel amorphous-silicon image sensor is proposed in this paper. The unit cell consists of an amorphous-silicon field-effect-transistor, an amorphous-silicon photo-conductor and an MOS capacitor. The fundamental properties of the unit cell are investigated and operation of a prototype integrated 8-bit linear array is described.
Gain Improvement by Self-Neutralization of Microwave SIT
Authors: Aiga Masao , Higaki Yukio , Kato Mari , Yukimoto Yoshinori
Published: March 2014

A very effective method for power gain improvement of microwave static
induction transistors (SITs) has been proposed and examined. The authors have found that self-neutralization occurs in common-gate configuration of an SIT. This arises from resonance of a gate-grounding inductance and a stray capacitance between electrodes of an SIT chip, and cancels out undesirable feedback components.
By applying the self-neutralization technique, high gain SITs such as a 1 GHz-10 W SIT of 12 dB gain, a 2 GHz-5 W SIT of 9 dB gain and a 1 GHz-80 W SIT of 8 dB gain were obtained.
(Invited) Design Considerations for High Power GTOs
Authors: Azuma Makoto , Kurata Mamoru , Ohashi Hiromichi
Published: March 2014

The major difficulty in designing high power GTOs is to increase maximum gate turn-off current I
ATO. Undoubtedly, the most determinant factor for I
ATO is the current crowding effect during the gate turn-off process. According to a theoretical model and basic experimental results, the p-base layer conductance should be high enough for the excess carrier extraction to occur efficiently. From results for actual whole devices, it was found that I
ATO varies proportionally to factor (V
J1/ρSPB) for given n-base thickness and resistivity. On the basis of these principles, success was achieved in realizing devices with more than 600 amperes I
ATO and from 600 to 2500 volts of forward blocking voltage.
4 kV, 1500 A Light Triggered Thyristor
Authors: Tada Akiharu , Kawakami Akira , Miyazima Tatsuo , Nakagawa Tsutomu , Yamanaka Ken-ichi , Ohtaki Kaname
Published: March 2014

A 4 kV, 1500 A, 85 mm dia. directly light triggered thyristor with a high power LED unit has been developed. The dv/dt and di/dt capabilities of this device are approximately equal to those of conventional electrically triggered thyristors, and the minimum light triggering power is less than 7 mW. These high capabilities are obtained by using a new two stage amplifying gate structure.
In order to drive this device by enough optical triggering power, a high power LED unit which launches the optical power of more than 70 mW into a bundled fiber has been developed. This LED unit consists of 20 GaAs-AlGaAs double-heterostructure LED's coupled with optical bundled fiber. By using this high power LED unit, the turn-on delay time of this 4 kV directly light triggered thyristor is reduced to less than 2 µs, which is almost equal to those of conventional electrically triggered 4 kV thyristors.
InGaAsP/InP Wavelength Division Solar Cells
Authors: Ito Nobuyuki , Uesugi Tsutomu , Sakai Shiro , Umeno Masayoshi , Hattori Shuzo
Published: March 2014

Two types of InGaAsP/InP wavelength division solar cells are fabricated. One of them includes a shallow homojunction and the other has a heteroface structure. A combination of the present cell and a conventional high efficiency GaAlAs/GaAs cell is proposed in this paper. The fabricated first type of cell exhibited the conversion efficiency of 11% for total solar illumination and 18.5% for filtered illumination with GaAs crystal. Neglecting the optical loss in filter material, the possibility that the 26% conversion efficiency will be obtained in the proposed system is demonstrated. The initial results on the second type of cell is presented and 8.71% conversion efficiency was obtained with a single p-n junction InGaAsP/InP heteroface solar cell.
Properties of Amorphous Si:F:H Film and Its Photovoltaic Characteristics
Authors: Kuwano Yukinori , Ohnishi Michitoshi , Nishiwaki Hidenori , Tsuda Shinya , Shibuya Hisashi
Published: March 2014

The optical and electrical properties of a-Si:F:H films deposited by an R.F. glow discharge in (SiF4+SiH4) and the photovoltaic properties of a-Si solar cells using the a-Si:F:H film were investigated. The dark conductivity and the activation energy of phosphorous doped a-Si:F:H film were 8.22 (Ω cm)-1 and 0.014 eV, respectively. The Staebler and Wronski effect for a-Si:H and a-Si:F:H films was investigated. The change in the dark conductivity of the a-Si:F:H film was smaller than that in the a-Si:H film. The best conversion efficiency for a Glass/ITO/p(H)-i(F:H)-n+(H) cell and a Glass/ITO/p(H)-i(F:H)-n+(F:H) cell were 2.1% and 2.5%, respectively. The change in the conversion efficiency of the a-Si:F:H and a-Si: H cells which occurs with an increase in the intensity of the incident light was measured. A decrease in the conversion efficiency of the a-Si:F:H cell was scarcely recognized.
Internal Photoemission in a-Si:H Schottky-Barrier and MOS Structures
Authors: Yamamoto Tomio , Mishima Yasuyoshi , Hirose Masataka , Osaka Yukio
Published: March 2014

Internal photoemission of metal/a-Si: H and metal/SiO2/a-Si:H systems have been measured in the temperature range 86 to 300 K. The height of the potential barriers at the Pd/a-Si:H and SiO2/a-Si:H interfaces have been determined to be 0.98 and 3.03 eV, respectively. The temperature coefficients of the Schottky barrier height and the optical band gap of a-Si:H have been obtained to be 3.3×10-4 and 2.7×10-4 eV/K, respectively. Appreciable quantum yield below the photoemission threshold for an MOS structure is found to be dependent on preparation conditions of a-Si:H , being attributed to electron emission from the filled gap-states in the film.
Schottky Barrier Solar Cells of Weakly Hydrogenated CVD Amorphous Silicon
Authors: Nakashita Toshio , Hirose Masataka , Osaka Yukio
Published: March 2014

Electronic properties of CVD a-Si were remarkably improved by hydrogen plasma annealing. As a result, the Schottky-barrier solar cells without an antireflection coating have provided a conversion efficiency of 2.7% at 100 mW/cm2, and no Staebler-Wronski effect has been observed in the hydrogenated CVD a-Si cell. It is also found that the fill factor is dependent on incident light intensity, because of changes in its series and parallel resistances by light illumination.