摘要:

AbstractIn a constant interval multifrequency measurement to evaluate optical device characteristics, considering that a constant time is required for the measurement at each frequency, a sweeping method that maintains the frequency during the measurement is desirable. Although this stepwise frequency sweeping can be achieved by changing the injection current of the semiconductor laser, the possible sweep frequency range is much wider for the temperature change than for the current change.In this paper, noting this wideband sweeping range by the temperature change, two frequency sweeping methods are proposed. In these methods, the frequency changes stepwise for the temperature change proportional to the time that is easy to realize, and are verified and compared experimentally. In this method, a part of the laser light is incident on the Fabry‐Perot resonator with the temperature change, and the transmitted light signal or its differential signal is fed back into the injection current. As a result, the feedback signal corresponding to the resonant characteristics controls the shift of the resonance frequency by the temperature change in the neighborhood of the resonance frequency, realizing the frequency sweep that changes stepwise with the spacing equal to the free spectral range of the Fabry‐Perot resona

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760301

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

年代:1993

数据来源: WILEY

摘要:

AbstractDifferential equation methods often are used for the analysis of the waves scattered by a dielectric grating. It is known that accurate numerical solutions can be obtained if the number of expansion terms of the spatial harmonics is increased. However, when the differential equation method is applied to a dielectric grating with an extremely large permittivity, the convergence speed of the solution becomes excessively slow in the TM wave analysis. Because of the increase of the computation time and the memory capacity, an analysis based on the differential equation method becomes difficult in practice.In this paper, it is shown that a boundary element method using Green's function satisfying the periodic condition is effective for the analysis. By introduction of pseudo‐periodic Green's function, the definition region for the integral equation is limited to the grating surface. In comparison to the boundary element method using the Hankel function, the number of linear equations is reduced. By means of numerical examples, it is shown that the convergence speed of the solution by the present method is faster and the computation time is significantly shorter than the solution by the differential equation method even in the TM wave analysis of a dielectric grating with a large los

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760302

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

年代:1993

数据来源: WILEY

摘要:

AbstractA numerical approach based on the finite element method using tetrahedral elements is proposed for the three‐dimensional discontinuity in electron waveguides. A three‐dimensional finite element method is applied for a region containing a discontinuity with an arbitrary shape. The uniform waveguide region connected to the discontinuity is treated analytically. The reflection probability and transmission probability are calculated, in addition to the current density, by combining the finite element method and the analytical solution. The transmission characteristics of a rectangular cavity between two electron waveguides are examined. It is found that the transmission probability of the three‐dimensional structure is much different from that of the two‐dimensio

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760303

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

年代:1993

数据来源: WILEY

摘要:

AbstractAs a useful approach to analyze the eigenstate of electrons inside a quantum box, the weighted potential method (WPM), already proven to be valid in a one‐dimensional system (wire structure), is applied to the zero‐dimensional one (box structure). The formulation and analysis were made for the quantum box structure of a finite potential barrier height in the presence of an applied electric field.The analysis, which takes into account the tunneling effect of electrons through the barrier when the electric field becomes strong, was carried out for the eigenstates. The method allows us to estimate the electron lifetime. A discussion also was made for an actual structure in which the effective mass of electrons is changed from a quantum well to a barrier region. The change in the eigenenergy was found to become more significant when increasing the number of the quantized direct

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760304

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

年代:1993

数据来源: WILEY

摘要:

AbstractOpen‐type waveguides with homogeneous cladding can be analyzed by the finite element method (FEM) with the multipole expansion method. In this paper, we propose a new connection method in which the fields described by the FEM and by the multipole expansion are combined at the connection boundary between the finìte inner region and the infinite outer region by using Galerkin method. By means of this method, we can analyze open‐type waveguides with higher accuracy and less amount of calculation than conventional FEM. In addition, there is no difficulty arising from spurious mode and no restriction between the number of the basis functions of the FEM and that of the multipole expansion functions on the connection boundary. The final matrix equation is symmetric. The validity and usefulness of the method has been demonstrated in the example of a rectangular dielectric waveguide and an elliptical f

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760305

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

年代:1993

数据来源: WILEY

摘要:

AbstractIt has been analyzed theoretically and verified experimentally that fixed pattern noise (FPN) is generated by the charge transfer loss when the charge in the CCD imager device generated by photoelectric conversion is imaged with a charge partitioning mode. This is done by removing the unnecessary nonsignal charge and reading out the signal charge. The result shows that the transfer loss due to the removal must be less than 10−4to achieve even an ordinary picture quality with signal‐to‐noise (SN) ratio of 60 dB when the signal in the charge partitioning mode is one‐tenth the total charge. Furthermore, for a high‐quality image with SN ratio above 70 dB, the transfer loss in reading two kinds of charge must be less than 10−5which is almost a perfect char

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760306

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

年代:1993

数据来源: WILEY

摘要:

AbstractDC‐freeing of write waveform is an important technique in digital magnetic recording. In this paper, it is achieved by using write equalization, which is one of the dc‐freeing methods, and on the read side, read equalization, which not only can reduce high‐frequency noise but also has little degradation of eye opening. A new write and read equalization method developed by investigating it from a synthetic viewpoint is proposed along with a signal detection method which brings out the best in the equalization method.First, it is shown that it is possible to dc‐free by the write equalization and then a read equalization and signal detection method is described which enables high signal‐to‐noise ratio (SNR) to be obtained by combining with the write equalization. Furthermore, it is clarified by computer simulation that our proposed system shows an excellent error rate performance compared with the combination of NRZ recording code and integrated detection, which is well known for its good perform

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760307

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

年代:1993

数据来源: WILEY

摘要:

AbstractTwenty‐four pairs of respective Ag, AgPd70/30, AgPd40/60, and Pd contacts are mounted on 24 miniature relays as pairs of electrical contact and switched the 30V, 10A DC resistive circuit on and off 100,000 times with the 1‐s closing period and 2‐s opening period. At each closing period, the contact resistance was measured with 10‐A circuit current.For all the materials, the histograms of the contact resistance averaged over 24 contact pairs from the start of opening/closing operations to 100 operations are clustered at approximately one location. The relation of the average contact resistance value among the four materials is the same as the relation of the resistivity and hardness. Therefore, the contact resistance at the initial stage of opening/closing operations is attributed to constriction resistance.For the case of Ag and Pd samples, the average contact resistance during the 100,000 operations depends little on the number of operations. Also, it is approximately the same as the average contact resistance during the initial 100 opening/closing operations. However, for the AgPd30% sample, the variation width increases with the switching operations. This is attributed to the fact that a selective evaporation of Ag from the contact surface during the arc discharge occurs and the alloy composition at the true contact surface changes repeatedly for each switching, with a resultant increase in variation of the average contact res

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760308

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

年代:1993

数据来源: WILEY

摘要:

AbstractA hybrid‐excitation technique using plasma excitation and photoexcitation in chemical vapor phase reaction has been developed. Using this technique, the silicon surface was nitrified in a mixture of ammonia (NH3) and hydrogen (H2) gases. First, a (100) Si substrate heated at 180°C was illuminated by ultraviolet ray (wavelengths: 184.9 nm and 253.7 nm) under NH3atmosphere. At the same time, hydrogen radicals generated by decomposition of H2gas in an RF (13.56 MHZ) inductive discharge tube were supplied to the substrate. Auger analysis indicated that the (100) Si surface up to about 1 nm in depth was nitrified and that the hybrid excitation was based on the synergy effect of photoexcitation and hydrogen radical excitation.Next, staggered‐structure thin‐film transistors were fabricated using amorphous Si whose surfaces nitrified by the foregoing method and the conventional plasma excitation method. It was found that when the hybrid‐excitation method was used, the field effect mobility was highest. In the gas analysis of hydrogen radical excitation, the presence of hydrazine was confirmed. Using this observation, the direct nitrification mechanism in the hybrid excitation was

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760309

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

年代:1993

数据来源: WILEY

摘要:

AbstractA method to calculate the current‐voltage characteristics and its distribution of a polysilicon thin‐film transistor as a function of grain size has been developed. The simulation was based on a model for a potential distribution in each grain and the grain size distribution in a channel. The grain sizes (both observed and assumed) were used to set a grain size distribution in a channel, leading to determination of the number of grains and their location in the channel.The thermionic emission by taking into account the modulation of a grain potential barrier due to a gate‐drain electric field was calculated, and then the current‐voltage characteristics were determined by a self‐consistency method. Applying this method to a large grain polysilicon thin‐film transistor grown by a solid‐phase growth method, the static characteristic and its variation could be simulated successfully by having only two adjustable parameters of interface trap density and grain boundary trap density. Based on the present method, one can obtain a grain size distribution necessary to obtain desirable electric characteristics and thus can have a guideline for a proces

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760310

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

年代:1993

数据来源: WILEY