摘要:

AbstractVarious waveguides made of different materials with complex configurations have been reported for use at the millimeter‐wave frequencies to optical wavelength. In general, it is difficult to analyze vectorially the characteristics of the waveguide with a three‐dimensional shape.In this paper, the spatial network method using all of the electromagnetic field components is employed as a vector analysis method to analyze a rectangular waveguide loaded with an anisotropic material with an extremely high relative permittivity. As the anisotropic material, the iron‐doped rutile used in a traveling‐wave maser is assumed.First, the propagation constant for the basic mode of the rectangular waveguide loaded completely with an anisotropic material is obtained. Next, the change of the propagation characteristics for the symmetric and non‐symmetric cases is studied for a rectangular waveguide partially loaded with an anisotropic material. The electromagnetic field distributions are presented for the case where the relative permittivity tensor of the anisotropic material has only the diagonal terms and where off‐diagonal terms exist. By means of the time domain analysis, the wave propagation in an anisotropic material can be found successively so that the effects of the boundary shape and the medium condition can be kno

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740801

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

年代:1991

数据来源: WILEY

摘要:

AbstractWith the recent advancement in semiconductor technology, high‐frequency applications of the elements have been developed rapidly. In the high‐frequency region, coupling of electromagnetic field and the elements cannot be defined by current and electrode voltage. It must be treated as a whole system.To solve this problem, unified analysis of electromagnetic field and semiconductor devices is required. In the past, the solution of the steady Poisson equation has been the principal goal in the analysis of semiconductor elements. However, for the devices operating at frequencies higher than microwave frequencies, it is strictly necessary to solve the Helmholtz equation considering time and loss terms.This paper explains that the unified analysis of electromagnetic field and semiconductor devices is possible by a combined equivalent circuit of scalar and vector wave equations along with Lorentz gauge or continuity equation, for a system including space charge and current. Moreover, the validity of this method is checked by applying it to a simple exam

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740802

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

年代:1991

数据来源: WILEY

摘要:

AbstractWhen the height of a tapered waveguide with its characteristic impedance changing in ann‐th power cosine profile with a varying cutoff frequency is varied, a resonance occurs near the cutoff frequency. In anticipation of improved rising properties of the insertion loss and the return loss, the reflection and transmission coefficients of the cutoff filter are derived. These coefficients are obtained numerically by solving the Runge‐Kutta method in which the differential equation valid for the rectangular TE10mode in a tapered waveguide satisfies the boundary conditions at the waveguide junctions.Next, the characteristics of the filter are analyzed by introducing a shape factor which indicates the rising property of a single taper near the cutoff frequency. Property charts are developed which can be used for deriving a small and high‐performance taper shape satisfying the requirements as a high‐pass filter. It is demonstrated that a small size and high performance can be realized by varying the

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740803

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

年代:1991

数据来源: WILEY

摘要:

AbstractAs a new power divider/combiner, a wideband microwave ladder‐type power divider/combiner with simple multiple branching structures is proposed in which probe pairs are provided to waveguides in a ladder shape. Based on the equivalent circuit, a design formula for a complete power division/combining is derived as well as the optimum coupling phase shift in the divider and combiner in the construction of a divider/combiner system. The frequency characteristics of the transmission efficiency of a divider (or combiner) alone and a divider/combiner system are analyzed numerically in terms of the admittance value of the probe pair so that the upper limit of the relative bandwidth of each stage (which is equal to the number of probe pairs) is derived. In the × band, 1–3 stage (2–6 port) divider/combiners were constructed.By means of the experiment of the transmission characteristics of the divider (or combiner) alone and the divider/combiner system, broadband characteristics were confirmed which agree well with the analytical results. In the case of a three‐stage ladder‐type divider/combiner, the reduction of the efficiency in the range of ±0.5 GHz from the center frequency (9 GHz) was less than 0.36 dB in a divider alone and less than 0.48 dB in the overall characteristics of the divider/combiner system. Further, isolation was studied theoretically and experimentally. In addition, the measured results were explained. It is demonstrated that the isolation can be improved without degrading the broadband characteristics by reducing the susceptance value of the

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740804

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

年代:1991

数据来源: WILEY

摘要:

AbstractAn attempt has been made to use a spatial light modulator to realize a system which controls the optical phase in a two‐dimensional (2‐D) fashion. Many of the spatial light modulators make use of the intensity modulation of the light. Very few can be used purely as a phase modulator. The microchannel spatial light modulator (MSLM) is an electron tube made of a photocathode, microchannel plate (MCP) and an electrooptic crystal (55‐deg cut LiNbO3). A theoretical study is conducted on the mechanism in which the optical phase is modulated by the writing optical energy incident on the photo‐cathode. To measure the phase variation by the device, Michaelson interferometer was used in the reading optics. The variation of the interference light intensity by the writing optical energy is obtained experimentally and from the obtained value the phase variation was derived. It is found that the phase can be inverted by the writing of the optical energy of 18 nJ/cm2when the reading light (γ = 632.8 nm) polarized in the direction normal to thex‐axis of the cryst

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740805

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper describes a homogeneously oriented LCD with a homogeneously oriented Np driving layer and a homogeneously oriented Np compensator and its characteristic. In general, in such an LCD, theV‐Tcharacteristic improves as 〈Δn〉10d1becomes larger. When the elastic constant ratioK33/k11is small and the dielectric constant ratio is close to unity in the Np material, theV‐Tcharacteristic remains sharp even if 〈Δn〉10d1is small. Considering both high time‐division driving and low‐voltage driving, vpandnshould be chosen so that 〈Δn〉= 〈Δn〉p= 〈Δn〉ndoes not deteriorate. Using ZLI‐2842 (manufactured by Merck&Co., Inc.), 〈Δn〉 of 7.5 percent was obtained when 〈Δn〉10d1= 0.76 μm, where the achromaticity was comparable with that in the VAN type. As 〈Δn〉10d1increased, the viewing angle characteristic became worse. In a cell with 〈Δn〉10d1suitable for high time‐division driving at a duty cycle lower than 1/200, the viewing characteristic was worse than those in the VAN CSH types. However, in a homogeneously oriented Np LCD, the instability caused by the dynamic scatter

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740806

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

年代:1991

数据来源: WILEY

摘要:

AbstractPartially oxidized cobalt films were deposited by the reactive evaporation method on an underlayer Au film and on a polymer film with a rough surface. The purpose of this study is to investigate the influence of these underlayers on the structure and perpendicular magnetic anisotropy of the partially oxidized cobalt films. The gold film was sputter‐deposited by using an Au target. The acceleration voltage and sputtering period for Au deposition were varied to form an Au film with different surface textures, i.e., island‐like, mesh‐like, and flat surfaces.CoOx films were deposited on these underlayers. The measurement of the magnetic properties and the SEM observation of the film cross section were carried out. When a CoOx film was deposited on an Au film with an island‐like surface texture, the CoOx film had a columnar structure perpendicular to the underlayer surface and the diameters of the columns were small. Because of this columnar structure, the perpendicular magnetic anisotropy was improved. When a CoOx film was deposited on a polymer film whose surface was roughened by sputter‐etching, the CoOx film had a columnar structure with a small columnar diameter.From the foregoing results, it was found that the columnar structure and perpendicular magnetic anisotropy of a CoOx film can be controlled by changing the surface condition of the u

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740807

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe short‐channel effect in thin‐film SOI MOS‐FETs was analyzed by two‐dimensional, two‐carrier simulation. In thin‐film SOI MOSFETs, the channel length dependence of the threshold voltage is influenced strongly by the avalanche effect caused by impact ionization. It was found that the short‐channel effect is enhanced by the avalanche effect.The holes generated by impact ionization raises the substrate potential, causing a decrease in the potential barrier between the source and substrate. In bulk MOSFETs, the potential barrier is not affected by the holes generated by the avalanche effect because the holes flow into the substrate electrode. However, in thin‐film SOI MOSFETs, the potential distribution near the source is influenced strongly by the holes because the holes flow into the source. The holes generated by the avalanche effect degrade the punch‐through breakdown voltage. The punch‐through breakdown voltage is highest when the SOI layer has a certain thickness. When the layer thickness is lower than a certain thickness, the punch‐through breakdown voltage decreases. The punch‐through breakdown voltage is lowest when the underlying oxide film

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740808

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

年代:1991

数据来源: WILEY

摘要:

AbstractA process to form an IC with an EPROM (erasable programmable ROM) and EEPROM (electrically erasable PROM) was a developed and a module was tested. Fabricating a floating‐gate type EEPROM and the process to achieve high reliability in write/erase performance and the high data‐retention characteristic were investigated. The write/erase endurance is higher when the tunnel oxidation is carried out by wet oxidation than when carried out by dry oxidation.As the temperature for forming the inter‐polyoxide increases, the leakage current decreases but the write/erase endurance decreases. As the tunnel oxide film becomes thinner, the write/erase endurance decreases. The passivation layer has a great influence on theVthwindow and data‐retention characteristics. When the passivation layer is a P‐SiN, the foregoing characteristics are poorer than when a PSG film is used. However, if PSG and P‐SiO films are formed under the P‐SiN film, the degradation of the forementioned characterist

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740809

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

年代:1991

数据来源: WILEY

摘要:

AbstractRecently, the pattern width in semiconductor devices has become as narrow as a submicrometer. As the pattern width decreases, the current density increases, thereby causing the breakage of the conductors due to electromigration and excessive heat generation.In the inductive thin‐film magnetic head used for the magnetic disc system, the number of wire windings in a coil should be high and the resistance should be low to achieve high output and low noise. To achieve these requirements, the aspect ratio of the conductor should be high and the conductor should be made of copper (Cu).The purpose of this study is to pattern fine Cu conductors with a high aspect ratio using the lift‐off technique. In the lift‐off technique, it is important to form a thick resist pattern with inverted‐trapezoidal cross section. In this study, image‐reversal photoresist was used and the conditions of exposure, heat‐treatment, and development were optimized to obtain a frame suitable for lift‐off. As a result, it was found that the Cu conductor with a pattern width of 1 μm and an aspect ratio over 2 could

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740810

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

年代:1991

数据来源: WILEY