Table of Content

31 December 1991, Volume 9 Issue 4

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Articles

PRINCIPLE OF DESIGNING SILICON PHOTOVOLTAGE MEASURED CELLS

AN QILIN, SHI WEIMIN, SHI JUYUAN

1991, 9(4):  283-289. 

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The principle of designing silicon photovoltage measured cells is discussed The effect of impurities, junction depth and surface recombination on the main parameters are also discussed. The main parameters are open-circuit voltage, short-circuit current, spectrum response and dark current. For application sake, the effects of series and shunt resistances on the linearity of the cell are analysed. In the last part of this paper, the mathematical model of temperature effect and the relationship between shunt resistance and the typical circuit design are demonstrated.

EXTREMELY LOW VELOCITY MEASUREMENT BY MEANS OF SPACIAL MODULATED LASER BEAM

SUN WEZHEN, GUO JIHUA, YIN CHUNYONG

1991, 9(4):  290-296. 

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In this paper a new laser Doppler velocimeter for extremely low velocity is introduced. The spacial light modulation and time dividing technique are used to clean-up low frequency noise which is close to the measurand. The principle of the method, optical diagram, and signal processing system are described. The measuring range is (300μm/s-0.02μm/s), and the accuracy is higher than 2%. An experimental result of a heating soldering iron Is given.

FOLDOVER EFFECTS AND THE SECOND-ORDERSPIN-WAVE INSTABILITY THRESHOLD OFFMR IN YIG SINGLE CRYSTAL FILMSUNDER PERPENDICULAR PUMPING

ZHANG YOUTING

1991, 9(4):  297-301. 

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Experimental results of the foldover effect in FMR for YIG single crystal films under perpendicular pumping were reported by the author and his co-workers. The objective of this work was to further analyze these experimental results, and to discuss the second-order spin-wave instability threshold for film samples. Analytical results indicated that the foldover of FMR at high continuous-wave power excitation conditions was mainly due to the sample heating. There was no obvious foldover for FMR with static magnetic field in the film plane, but foldover for FMR with static magnetic field perpendicular to the film plane was observed under pulsed microwave excitation conditions.

KINETICS OF ELECTRON CAPTURE IN SOLID DIELECTRIC UNDER HIGH ELECTRICAL FIELD

LIU FUD, E YANG BAITUN, TU DEMIN, LIU YAONAN

1991, 9(4):  302-308. 

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The kinetic properties of electron capture in solid dielectric under strong electrical field are studied with surface potential measurement in this paper. With respect to the different mechanisms of carrier injection by the field, the authors take thermal emission and impact ionization into account, respectively. The improved first-order capture kinetic equations can explain qualitatively the processes of electron capture and the variation of the steady-state values captured by traps with the fields. It is found that in the range approaching the field of breakdown, the electrons in the conduction band will collide with the trapped, resulting in the trapped electrons detrapping. Once the detrapping reaches a certain value, breakdown occurs.

THE TECHNOLOGY AND CHARACTERISTICS OF LDD MOSFET

ZHENG QINGPING, ZHANG QIANLING, RUAN GANG, CHENG XIAO

1991, 9(4):  309-314. 

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Lightly Doped Drain (LDD) MOSFET developed from the conventional MOSFET, is a new structure for MOS devices. Some short channel effects including the hot electron effect in this new structure can be restrained effectively. In this paper a comparison between overcut etching and side wall technology for LDD MOSFET is given. It shows that the side wall technology is a more precise one to control the length of the lightly doped drain region. Combining the side wall technology with the Si-gate NMOS technology, the LDD MOSFET with 1 micrometer channel length is made successfully. The results of test show that the breakdown voltage of LDD MOSFET is higher than that of the conventional MOSFET over 3 volts and the short channel effects of the threshold voltage are restrained obviously. The LDD MOSFET is a suitable structure for VLSI.

NUMERICAL SOLUTION TO POISSON'S EQUATION FOR MIS STRUCTURE

WU YINGQIAN

1991, 9(4):  315-322. 

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The numerical solution to one-dimensional Poisson's equation for MIS structures is described in detail in this paper. Newton's iterated formulation for a nonuniform mesh is derived and the suitable boundary conditions for MIS structures are also presented. As an example of the application of the numerical method, the Ψ_S-V_G relation and the interface trap density are obtained by use of the high frequency C-V characteristic for a MOS structure whose SiO₂ film is thermally grown. This method is compared with the quasi-static method experimentally. The results are well agreed, but the former method is much simpler in fabricating and measuring the example. Therefore, this method is suitable for the regular process monitoring.

THE APPLICATION OF PATTERN RECOGNITION AND LINEAR PROGRAMMING IN THE OPTIMIZATION OF THE REACTION PROCESS OF F-53 TELOMER

XU CHI, ZHANG ZHONG, LU JINZHONG

1991, 9(4):  323-328. 

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The technological condition of the reaction process and the proportion of raw materials of F-53 telomer (IC₂F₄OC₂F₄SO₄F) were optimized by computerized pattern recognition and linear programming. The target function based on the discriminant introduced from the transformation of multi-dimensional pattern space can determine the optimizational direction and best combination of all factors. Using the optimization method the yield rate increases from 43% to 57.6%. The method has great potentialities for the decrement of the expense of raw materials and that of production cost.

LUMINESCENCE OF Bi³⁺ AND Eu³⁺ IONS IN Li_0.3MeAl_0.3-x-ySiO₃(Me=Mg, Ca, Sr, Ba)

LI BIN, TIAN YIGUANG, BAI YUBAI

1991, 9(4):  329-334. 

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The luminophors of silicates Li_0.3MeAl_0.3SiO₃:Eu, Bi (Me=Mg, Ca, Sr, Ba) were synthesized and luminescence properties of Bi³⁺ and Eu³⁺ ions were studied. The effects and regularities of Me (Ⅱ) ions on the luminescence of Eu³⁺ and Bi³⁺ ions were also investigated. The study on the luminescence of silicates Li_0.3MeAl_0.3SiO₃:Eu, Bi indicated that there were energy transitions from the Bi³⁺ ion to Eu³⁺ ion and that Bi³⁺ions acted as both sensitizer and co-activator. The best promoting result of Bi³⁺ to Eu³⁺ was obtained when Me was Sr, i. e. the relative intensity was the highest by exciting the Bi³⁺ ion. The main emission of the Eu³⁺ion was from ⁵D₀-⁷F₁ transition for Me=Mg, Oa, Sr, and from ⁵D₀-⁷F₂ for Ba.
Under UV excitation of 395nm, the luminescence intensity of Eu³⁺ in Li_0.3BaAl_0.3SiO₃:Eu was 2 times that of Y(V, P)O₄:Eu, for both, of ⁵D₀-⁷F₁ and of ⁵D₀-⁷F₂ transition emissions. The experiment results demonstrated that the optimum synthesis condition was 950℃ and 4 hours sintered in twice and silicate Li_0.3BaAl_0.3SiO₃ was an excellent host lattice to obtain efficient photoluminescence materials.

THE STOCHASTIC PROCESS MODEL OF AGING OF POLYMER MATERIALS

SHI TUO, SHI ZHE

1991, 9(4):  335-340. 

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According to the general law of aging of polymer materials, the mathematical model of the aging process has been obtained using the method of stochastic proces and the life distribution function has been derived. The reliability analysis of the failure of the polymer materials' due to aging is discussed.

A STUDY ON INFLUENCE CF THE “IMMERSION” TECHNOLOGY ON THE QUALITY OF Nd:YAP CRYSTAL BY MEANS OF THE POSITRON ANNIHILATION LIFE SPECTROSCOPY

SHI ZIKANG

1991, 9(4):  341-346. 

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In this paper, we report the research on the effect of the "immersion" technology adopted in the Nd:YAP crystal growth process by the Czochrolski method on the quality of the crystal. We find that the "immersion" technology can improve the crystal quality.

AN APPROACH TO THE PRECISION OF TEMPERATURE CONTROL IN THE SCR TEMPERATURE CONTROL SYSTEM

LU ZHIPING, XUE ZHILIN

1991, 9(4):  347-353. 

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This article studies the effect of the interference on the furnace temperature fluctuation in the SCR temperature control system at a lesser lag. The mathematical expressions of the furnace temperature fluctuation are derived, and the relationship between the furnace temperature fluctuation and the system parameters is analyzed. Then a comparison is made with the experimental results. It is hoped, that in this way, we can provide a theoretical basis for improving the precision of the temperature control system.

SUBFIELD MAP METHOD——AN ALGORITHMRESEARCH FOR DISTRIBUTIVE SORT

YANG XIANZE

1991, 9(4):  354-358. 

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This article puts forward a new sort algorithm … the subfield map quick sort method. It makes a great amount of modification based on Ref.[5] and belongs to a distributive sort. In this algorithm, the key words; distribution is considered only, comparison and exchanges of key words being omitted. The purpose of the work is to solve the problem:why the sort method of Ref.[5] fails when the key word is long and, the data are not equally distributed. The theoretical analysis and the experimental results prove that the efficiency of the algorithm is higher than Hoare's in the ordinary case, and the algorithm is appropriate for large-scale information sort.

APPLICATION OF FUZZY MATHEMATICS IN THE APPRAISAL OF SOIL QUALITY

WAN CUNXU, ZHANG XIAOYUNG

1991, 9(4):  359-365. 

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Fuzzy clustering analysis is used to classify the different samples of the soil resources of the loess plateau, in accordance with their physicochemical properties.
On this basis, then, the samples are arranged in order of quality, using grade-2 Fuzzy synthetical judgement.It is shown that the Fuzzy approach in the quantitative research of soil, is far better than any other quantitative approach. It can provide a reliable scientific basis for the protection and exploitation of soil resources. Therefore it is regarded as a basic approach to the appraisal of soil quality.

Research Notes

STUDY AND APPLICATION OF THE ROOM TEMPERATURE GAS SENSING ELEMENT

LI WENFAN, LIU XIUYING

1991, 9(4):  366-370. 

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A new type of room temperature gas sensing element of SnO₂ has been made.The sensing characteristics of this element have been examined for combustible gas and smoke. The results show that the element has short response time, and is sensitive, stable, and cheap. Experiments confirm that the quick response and sensitivity of the element are due to its high bulk temperature. The element has now been put inot practical use.