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1987 Vol. 9, No. 5
Display Method:
1987, 9(5): 385-394.
Abstract:
The concepts of power waves, exchangeable power, power wave reflection coefficients and generalized scattering parameters are explained, and some extensions are made. Several examples for applications are cited. They illustrate that these tools are very useful in dealing with microwave active circuits, especially those including negative resistances.
The concepts of power waves, exchangeable power, power wave reflection coefficients and generalized scattering parameters are explained, and some extensions are made. Several examples for applications are cited. They illustrate that these tools are very useful in dealing with microwave active circuits, especially those including negative resistances.
1987, 9(5): 395-403.
Abstract:
A program developed for analyzing general N-phase SC circuits is described. The program can perform the time-domain, frequency-domain and sensitivity simulation, the multiple objective optimization, and the calculation of the transfer poles of SC circuits. No topological or duty-cycle constraints are imposed on the SC circuits. The methods of calculating the SC circuits poles using modified nodal method and the circuit sensitivity with respect to capacitor ratios are given, and the multiple objective optimization method for SC circuits is developed. Two examples are included to illustrate the capabilities of the program.
A program developed for analyzing general N-phase SC circuits is described. The program can perform the time-domain, frequency-domain and sensitivity simulation, the multiple objective optimization, and the calculation of the transfer poles of SC circuits. No topological or duty-cycle constraints are imposed on the SC circuits. The methods of calculating the SC circuits poles using modified nodal method and the circuit sensitivity with respect to capacitor ratios are given, and the multiple objective optimization method for SC circuits is developed. Two examples are included to illustrate the capabilities of the program.
1987, 9(5): 404-412.
Abstract:
A high precision logarithmic amplifier with wide passband is achieved by using the charge and discharge of RC and the method of pulse-width modulation. It can be used in the astronomy, astronavigation, accurate measurement, communication etc. The theoretical analysis of the circuit is given. A practical circuit is constructed, and the experimental result shows that the logarithmic function for the circuit reaches 99% of the theoretical value.
A high precision logarithmic amplifier with wide passband is achieved by using the charge and discharge of RC and the method of pulse-width modulation. It can be used in the astronomy, astronavigation, accurate measurement, communication etc. The theoretical analysis of the circuit is given. A practical circuit is constructed, and the experimental result shows that the logarithmic function for the circuit reaches 99% of the theoretical value.
1987, 9(5): 413-419.
Abstract:
The problems of adaptive nonparametric detectors are considered. The major reason behind the increasing engineering interest in nonparametric signal detectors is their ability to maintain CFAR (Constant-False-Alarm-Rate) at the detector output for a broad class of noise distributions. The false alarm probability (Pfa) is not constant, when the input noise is not the sequence of IID (Identical Independent Distribution) variance. In order to maintain CFAR the weight of the detection range cell of the detector can be changed continuously by different output value of IIR filter for measuring the correlation coefficient of the input noise. The closed form expressions for detection probability (Pd) and Pfa of the weighted nonparametric detectors are derived. The ARE (Asymptotic Relative Efficiency) of the detectors is investigated. finally, the detection performance of the adaptive nonparametric detector is determined for a finite number of observations.
The problems of adaptive nonparametric detectors are considered. The major reason behind the increasing engineering interest in nonparametric signal detectors is their ability to maintain CFAR (Constant-False-Alarm-Rate) at the detector output for a broad class of noise distributions. The false alarm probability (Pfa) is not constant, when the input noise is not the sequence of IID (Identical Independent Distribution) variance. In order to maintain CFAR the weight of the detection range cell of the detector can be changed continuously by different output value of IIR filter for measuring the correlation coefficient of the input noise. The closed form expressions for detection probability (Pd) and Pfa of the weighted nonparametric detectors are derived. The ARE (Asymptotic Relative Efficiency) of the detectors is investigated. finally, the detection performance of the adaptive nonparametric detector is determined for a finite number of observations.
1987, 9(5): 420-427.
Abstract:
Clean Si (100) and (111) surfaces produced by the Ar+ ion bombardment and high temperature annealing techniques, and the epitaxial growth of nickel silicides on them at room temperature using molecular beam method are studied by reflection high energy electro diffraction (RHEED). The experimental results show that Si(111)77 and its negative zone RHEED pattern, Si(100)21, Si(111)1919 Ni and Si(100)42Ni structures are obtained, and the lattice structures of nickel silicide produced during epitaxy with low growing rate (0.16--0.5 per minute) is the same as that of silicon substrate.
Clean Si (100) and (111) surfaces produced by the Ar+ ion bombardment and high temperature annealing techniques, and the epitaxial growth of nickel silicides on them at room temperature using molecular beam method are studied by reflection high energy electro diffraction (RHEED). The experimental results show that Si(111)77 and its negative zone RHEED pattern, Si(100)21, Si(111)1919 Ni and Si(100)42Ni structures are obtained, and the lattice structures of nickel silicide produced during epitaxy with low growing rate (0.16--0.5 per minute) is the same as that of silicon substrate.
1987, 9(5): 428-434.
Abstract:
The control of Hg pressure is a major problem of LEP growth of HgCdTe. In this paper the lost of Hg and its affections and control in open tube sliding LEP system are analysed theoretically. A unique method of controlling Hg pressure, called pseudo-balance Hg pressure method is proposed. In this method, a circulatory system of Hg that is efficacious for control of Hg pressure is used. By experiments of growth conditions, the better way of LEP growth of HgCdTe was found. The HgCdTe epitaxial layers have been grown with mirror-like surface morphology, x=0.2110.002 and x=0.280.001, mobility of 1.81103cm2/Vs for p-type and 3.36105cm2/Vs for n-type (not annealed), carrier concentration of 1.041016/cm-3 for p-type and 1.091015cm-3 for n-type (not annealed) at 77K.
The control of Hg pressure is a major problem of LEP growth of HgCdTe. In this paper the lost of Hg and its affections and control in open tube sliding LEP system are analysed theoretically. A unique method of controlling Hg pressure, called pseudo-balance Hg pressure method is proposed. In this method, a circulatory system of Hg that is efficacious for control of Hg pressure is used. By experiments of growth conditions, the better way of LEP growth of HgCdTe was found. The HgCdTe epitaxial layers have been grown with mirror-like surface morphology, x=0.2110.002 and x=0.280.001, mobility of 1.81103cm2/Vs for p-type and 3.36105cm2/Vs for n-type (not annealed), carrier concentration of 1.041016/cm-3 for p-type and 1.091015cm-3 for n-type (not annealed) at 77K.
1987, 9(5): 435-440.
Abstract:
The dark defects in InGaAsP/InP DH LEDs are observed with an infrared line scanner. The dark structure appears before aging and it exists mainly in the form of dar kspot defect. The effect of the variety and concentration of the doping for p-InP confining layers on the dark defects is studied. The results show that the percentage of devices with dark defects is much lower for Mg or In-Zn doped devices than for Zn doped devices. It is believed that Zn is one of the important orign for the formation of dark defects. The growth rate of dark defects is studied both at room temperature and at 70--85℃. The results show that after aging for 15000 h at room temperature there are no dark defects newly appeared. But after agin for 2000 h at 70--85℃ some devices show newly formed dark structure with very slow growth rate.
The dark defects in InGaAsP/InP DH LEDs are observed with an infrared line scanner. The dark structure appears before aging and it exists mainly in the form of dar kspot defect. The effect of the variety and concentration of the doping for p-InP confining layers on the dark defects is studied. The results show that the percentage of devices with dark defects is much lower for Mg or In-Zn doped devices than for Zn doped devices. It is believed that Zn is one of the important orign for the formation of dark defects. The growth rate of dark defects is studied both at room temperature and at 70--85℃. The results show that after aging for 15000 h at room temperature there are no dark defects newly appeared. But after agin for 2000 h at 70--85℃ some devices show newly formed dark structure with very slow growth rate.
1987, 9(5): 441-450.
Abstract:
The eigen-frequency of the double-reentrant cavity is computed by classical method of the field matching. The results show that for the double-reentrant cavity with regular drift region, this method is superior to the others in higher accuracy and less computing time.
The eigen-frequency of the double-reentrant cavity is computed by classical method of the field matching. The results show that for the double-reentrant cavity with regular drift region, this method is superior to the others in higher accuracy and less computing time.
1987, 9(5): 451-457.
Abstract:
The high and low density sandwich CsI photocathodes have been developed and optimized to yield relatively stable and effecient systems for photon detecting in the 0.1-10 keV region. For sandwich CsI photocathodes, the photon detecting effeciency is 2-10 times higher than that oh-tained with the high density Csl photocathodes in the 0.1-10 keV region. The energy distributions of the photoemitted secondary electrons have been measured to be similar for the high density sandwich photocathodes and with about 2eV full-width-half-maximum. The high efficiencies and relatively narrow emitted electron energy distributions have made the CsI transmission photocathodes extensively useful in soft x-ray detectors and counters especially is x-ray streak camera applications.
The high and low density sandwich CsI photocathodes have been developed and optimized to yield relatively stable and effecient systems for photon detecting in the 0.1-10 keV region. For sandwich CsI photocathodes, the photon detecting effeciency is 2-10 times higher than that oh-tained with the high density Csl photocathodes in the 0.1-10 keV region. The energy distributions of the photoemitted secondary electrons have been measured to be similar for the high density sandwich photocathodes and with about 2eV full-width-half-maximum. The high efficiencies and relatively narrow emitted electron energy distributions have made the CsI transmission photocathodes extensively useful in soft x-ray detectors and counters especially is x-ray streak camera applications.
1987, 9(5): 458-464.
Abstract:
Using the priciple of electron cyclotron resonance, the microwave plasma with high degree of ionization and activity is obtained under the lower pressure from 10-3 to 10-4 Pa. In this paper, the influences of the microwave input power and gas pressures on the parameters of plasma in nitrogen and argon are studied with Langmuir probe, and mass spectrographic analysis is also made.
Using the priciple of electron cyclotron resonance, the microwave plasma with high degree of ionization and activity is obtained under the lower pressure from 10-3 to 10-4 Pa. In this paper, the influences of the microwave input power and gas pressures on the parameters of plasma in nitrogen and argon are studied with Langmuir probe, and mass spectrographic analysis is also made.
1987, 9(5): 465-468.
Abstract:
When the operating mode wave generated in a gyrotron is going through the output window section, in which the undesired scattering modes that may disturb the normal operating of gryo-tron can be excited by the discontinuities. The transmitting properties of the window section in a gyrotron are analysed theoretically. The approximate formulas for mode scattering on the radial step of cylindrical waveguides are derived. The frequency dependence of wave transmis-sions of the operating mode and undesired modes through the window system are obtained and discussed. The cold measurements show that the theoretical results are reasonable.
When the operating mode wave generated in a gyrotron is going through the output window section, in which the undesired scattering modes that may disturb the normal operating of gryo-tron can be excited by the discontinuities. The transmitting properties of the window section in a gyrotron are analysed theoretically. The approximate formulas for mode scattering on the radial step of cylindrical waveguides are derived. The frequency dependence of wave transmis-sions of the operating mode and undesired modes through the window system are obtained and discussed. The cold measurements show that the theoretical results are reasonable.
1987, 9(5): 469-472.
Abstract:
The stirless method and the electrophilic corrosive reagent is used for etching of the glass-core of Pb glass microchannel plate. The etching quality is examined by means of SEM and EDX, and it shows that there are no residues of the core glass. A reliable and reproducible measuring method of etching velocity is also proposed.
The stirless method and the electrophilic corrosive reagent is used for etching of the glass-core of Pb glass microchannel plate. The etching quality is examined by means of SEM and EDX, and it shows that there are no residues of the core glass. A reliable and reproducible measuring method of etching velocity is also proposed.
1987, 9(5): 473-476.
Abstract:
A pile-up masking technique using the conventional optical lithography and a two-step or three-step evaporation process is developed to fabricate the variable thickness superconducting microbridges of submicron. The l-V characterise of the microbridges made by the technique is measured at 4.2 k.
A pile-up masking technique using the conventional optical lithography and a two-step or three-step evaporation process is developed to fabricate the variable thickness superconducting microbridges of submicron. The l-V characterise of the microbridges made by the technique is measured at 4.2 k.
1987, 9(5): 477-480.
Abstract:
A new method for patterns making by using electron beam imaging in SiO2 film on silicon substrate is presented. The electron beam images in SiO2 film can form not only positive patterns but also negative patterns by using HF vapor etching and reactive media.
A new method for patterns making by using electron beam imaging in SiO2 film on silicon substrate is presented. The electron beam images in SiO2 film can form not only positive patterns but also negative patterns by using HF vapor etching and reactive media.
