摘要:

AbstractAmong magnetic recording tapes for such applications as mass storage systems, the antiabrasion properties of the magnetic layer along with storage life are major factors determining magnetic tape life. This paper examines the effect of magnetic layer structural parameters which affect durability and the signal‐to‐noise ratio. Several magnetic tape layer design conditions aimed at improving magnetic tape reliability and recording density are then presented. That is, in order to effect a highly durable binder structure, it is necessary to achieve appropriate mechanical characteristics (tensile strength ≥1 kg/mm2and elongation at break ≥40%) by crosslinking a large‐matrix, high‐molecular weight polyurethane as well as carefully adjusting the balance of each additive. On the one hand, lapping treatment is effective in improving the SN ratio, with a decrease of up to two‐thirds in surface roughness possible. At the same time, it is found that magnetic pigment content is an important factor limiting durability and that it is a sensitive structural parameter which must be determined based on its inverse relation to the SN ratio. Using a specially developed binder, we demonstrate that a highly durable magnetic tape capable of withstanding more than 108head scan passes is possible, that the use of lapping treatment can improve the SN ratio by 4 dB, and that a suitable value for the magnetic pigment content is on the or

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractAlthough low‐cost solar cells based on Se have recently been examined, there have been extremely little basic data which provide a guideline for the improvement of energy conversion efficiency. In this paper, to clarify the behavior of heterojunctions between Se and conductive oxides, an ITO/Se heterojunction has been fabricated and its basic electrical characteristics and impurity concentration distribution by x‐ray photoelectron spectroscopy have been studied. The ITO/Se heterojunction can be regarded as a Schottky contact based on capacitance‐voltage (C‐V) and photoelectric response characteristics. Also, in the current density‐voltage (J‐V) characteristics, the slope of lnJvs.Vis constant regardless of temperature. This has been explained in terms of the tunneling mechanism through interface states; Te (20 Å) introduced at the ITO/Se interface not only prevents the peeling of Se film during the thermal crystallization process, but also improves the diffusion potential and the barrier height by 10%. Although a part of the Te thermally diffused into Se layer forms an acceptor level and changes the impurity doping distribution, it does not especially affect the energy band, theJ‐Vcharacteristics or the spectral response. Since the diffusion potential determined from theC‐Vcharacteristics is approximately 1.5 times the open circuit voltage under AM illumination, this implies that SIS (Semiconductor‐Insulator‐Semiconductor) structures are more suitable for

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractAn integral equation method is used to analyze the scattering of the incident guided mode at the gap between two dielectric slab waveguides with arbitrarily shaped ends. As a typical example, a two‐dimensional model of the coupling gap, which occurs in the preheating stage of the fusion splicing of optical fibers is treated. The possibility is studied for indirect understanding of the situation of the coupling location from the measured values of the reflected light, transmitted light, etc. A detailed study is done for the correlation of the reflected, transmitted, radiated power and radiation patterns with the gap width and the end shape (functions of the preheating time). The reflected, transmitted, and radiated power change quickly within a short period but without significant characteristics. However, their envelopes indicate characteristic tendencies. The maximum of the reflected power and the difference between the maximum and minimum of the transmitted power decrease monotonically. The backward, rather than forward, radiation pattern varies more sensitively to the change of the end shap

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractConventional surface acoustic wave (SAW) devices mainly use Rayleigh waves that propagate on the substrate surface. Therefore, they require protective packaging and are expensive as well as unreliable. This paper reports an effort to develop SAW devices that do not require packaging. To this end we study the Stoneley waves propagating along the interface between the piezoelectric and isotropic materials. A range of material constants of isotropic materials is obtained which allows the Stoneley wave if combined with piezoelectric materials with various cuts and propagation directions. We obtain the relation of the allowable range to the maximum velocity of the Stoneley wave and the velocity of the Rayleigh wave. It is found that the Stoneley wave can be supported with a combination of glass and LiTaO3, PZT4and ZnO. It is not possible to concentrate the energy near the interface if LiNbO3and Bi12GeO20are used.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractTo realize low‐loss low‐crosstalk long‐length polarization‐maintaining fibers, this paper examines the “PANDA fibers” having a circular stress‐applying part which has a high design accuracy and ease of fabrication. Stress‐applied type polarization‐maintaining optical fibers generally have two orthogonal polarized modes, and their coupling causes crosstalk which makes the transmission of polarized mode through a long‐length of fibers difficult. To suppress this mode‐coupling, it is important (a) to make the modal birefringence larger, and (b) to reduce the deterioration of the symmetry of the stress applied. This paper examines the circular stress‐applying type PANDA fiber and compares it with two other types of PANDA fiber having the typical shapes of the stress‐applying part. As a result, (1) the structure parameters of the stress‐applying part which gives the maximum modal birefringence and a low loss, and (2) the mode‐coupling parameter, with the stress‐applying part deviated, which can evaluate the crosstalk characteristics, have been obtained. Based on the results of these theoretical analyses, the symmetry in the stress‐applying part is improved by using a large preform, and the increase of the modal birefringence by increasing the outer diameter of the fiber is carried out. The circular stress‐applying type PANDA fiber having a crosstalk as low

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractDue to its strong nonlinearity, computer simulation has been used in most cases to analyze the Josephson circuit. Thus, it is difficult to obtain the general prospect for the solutions and their errors are apt to accumulate. This paper proposed an analytical method to solve the stationary oscillation, produced in such a circuit with any higher harmonic components, and the calculated analytical results show a good agreement with those of computer simulation. A method is proposed to obtain solutions based on the combined concepts of the Fourier analysis and harmonic balance method, assuming in advance that the stationary oscillation solution includes any higher harmonic components. The stationary oscillation solutions produced in the captioned circuit can be analyzed with good results. This method is applicable to the analysis of any nonlinear circuits other than the Josephson circuit.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA two‐dimensional numerical model has been developed for the analysis of operation of a high electron mobility transistor (HEMT) based on the AlGaAs/GaAs heterojunction. In this model, the basic equations are formulated under the assumption that the band structure is continuous and Boltzmann statistics are applicable. Further, it is assumed that the velocity‐electric field curve of the two‐dimensional electron gas system is identical to that of the bulk GaAs. The calculations have been performed for the device with a 1 μm gate length and the following results have been made on the operating mechanism of the HEMT. 1 In the short‐channel HEMT, the electron velocity saturates in the channel directly below the drain‐side edge of the gate electrode and as a result the current also saturates. 2 In the HEMT operated in the saturation region, an electron accumulation region is formed in the GaAs layer below the drain‐side edge of the gate electrode. In this region, the current flow significantly extends into the bulk GaAs from the heterojunction interface. 3' A strong electric field concentration occurs in this region and the major portion of the applied drain voltage is sustained by this region. This concentration is limited in an extremely n

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA two‐dimensional device simulator HESPER, which can numerically analyze the AlGaAs/GaAs heterostructure devices, has been developed. This program was applied to a heterostructure bipolar transistor and its performance was compared with a homostructure device. As a result, it was shown that the transistor characteristics such as current gain and cutoff‐frequency are improved greatly by the introduction of a heterostructure. In addition, from carrier and potential distributions, the advantage of heterostructure devices was clarified. Moreover, HESPER was applied to a two‐dimensional electron gas FET, and the calculated transconductance values have agreed well with the measured results for different AlGaAs thicknesses. Furthermore, it was also suggested that the increasing mobility in the low electric field region and/or the saturation velocity mobility are effective to realize the high‐speed operation. That is, we can expect more excellent performance of the two‐dimensional electron gas devices at 77 K and/or in velocity oversho

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe versatile algorithms of two‐dimensional device simulation programs are studied in detail. We have separated the device simulator which is independent of the device structure and the user's analysis purpose, and the preprocessor that specifically deals with user interface. Moreover, the algorithms of the device simulator become the discretization by information obtained at the nodes only, electrode current definition at the nodes of electrodes, initial guess using two‐dimensional numerical depletion approximation, and the iterative operation of the device simulation by step design. Using these algorithms we developed a two‐dimensional device simulator UNISAS, and confirmed the validity of the versatile algorithm using an example of NMOS. Step design is used for the analysis of the avalanche phenomenon of NMOS. Solving for the two carriers, we have explained easily the flow of electrons and holes in the avalanche breakdown phenomenon. Moreover, by changing only input data, we have easily analyzed the five‐ga

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractWe propose a process evaluation method using channel‐doped MOS devices and process/device simulators for quantitative evaluation of contamination and surface condition. The amount of contamination is determined by comparison of the measured and simulatedC‐Vcharacteristics of an MOS capacitor. Then the MOS FET is evaluated by comparison with a theoretical idealI‐Vcharacteristic calculated from the MOS capacitor measurement data and the doping profile. The surface condition is evaluated by determining the carrier mobility from MOS FET characteristics. With these evaluation methods, we develop a new process evaluation algorithm to determine the cause of processing irregularities, whether due to contamination, damage, faulty pattern delineation, or other factors. By combining a process data base and process device simulator, we develop a process evaluation system to facilitate application of the new evaluation method. It is applied to the evaluation of MOS LSI proce

ISSN:8756-663X    

DOI:10.1002/ecjb.4420680310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY