排序方式: 共有19条查询结果,搜索用时 15 毫秒
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The reduction of the current amplification factor of a wide-base transistor, with growing doping concentration in the base region, is investigated. A method for the determination of the minority-carrier lifetime τn in the base region and the emitter Gummel number G e is developed. The method is based on transistor structures differing only in the base width. It was found that the lifetime τn decreases according to the power law τn~N -0.45A. This result is analyzed for different recombination processes. Good agreement is obtained if shallow impurities acting as recombination centers are assumed. The injection-limited current gain βγ decreases significantly with an increase in the total number of the doping concentration of the base, reaches a broad maximum, and then falls slowly. The maximum value of G e is found to be 1.1×1014 cm-4-s in good agreement with theoretical results. Finally, the contribution of the injection efficiency γ and the transport factor αT to the current gain α are determined. It is found that α is limited mainly by the injection efficiency γ 相似文献
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Zekry A. Abdel-Naby M. Ragaie H.F. El Akkad F. 《Electron Devices, IEEE Transactions on》1993,40(2):259-266
Capacitance-voltage and conductance-voltage characteristics of RF-sputtered ZnCdS films on ZnTe single crystals are studied as a function of frequency up to 1 MHz. It is found that the measured capacitance decreases with frequency while the conductance increases. A physical circuit model of the junction is proposed to explain this dependence. A relationship relating the junction capacitance to the polycrystalline film properties and the built-in voltage of the junction is derived. It shows that the junction capacitance is related to the average carrier concentration rather than the doping concentration of the polycrystalline material. From a C -2 versus V plot an average carrier concentration in the films which is in good agreement with that obtained by Hall measurement is obtained. The lower average electron concentration in the ZnCdS film near the substrate is due to either interdiffusion of Cd from the film into substrate or due to higher density of grain boundary states in the starting deposition portion of the film 相似文献
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Zakaria Hassan Abdelwahab Talaat A. Elgarf Abdelhalim Zekry 《Information Security Journal: A Global Perspective》2020,29(6):341-365
ABSTRACT Confidentiality and integrity processes are based on SNOW and ZUC algorithms. These standardized algorithms are designed by the 3rd Generation Partnership Project (3GPP) for advanced mobile communication systems. Each algorithm has two S-boxes in its nonlinear layer structure. This paper proposes three different approaches to enhance the security level of both algorithms. The first approach aims to select the best combination of two S-boxes in the nonlinear part of each algorithm. Results showed that the best randomness properties are achieved by combining the Feistel structure (S1-box) and Rijndael (S2-box) in the SNOW algorithm and New Rijndael (S1-box) and Rijndael (S2-box) in the ZUC algorithm. The second approach aims to increase the nonlinearity and complexity of these algorithms by selecting a strong S-box to cascade the best-existing two S-boxes for both algorithms. The third approach is an extension of the former, based on a dynamic reform of such S-boxes as a function of the “Authentication Token” to increase the computational complexity of the upgraded two algorithms. These proposed upgrades are simulated by C language and tested successfully for their statistical properties using the standard NIST SP 800-22 test suite. 相似文献
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Mohsen Saeed Zekry Abdelhalim Youssef Khaled Abouelatta Mohamed 《Wireless Personal Communications》2021,116(4):3143-3164
Wireless Personal Communications - In this paper, a wearable medical sensor system is designed for long-term healthcare applications. This system is used for monitoring temperature, heartbeat,... 相似文献
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This paper presents a fast CAD model to calculate plasma-spreading velocity in large area thyristors. The model is based on the two-dimensional two-transistor circuit model of a thyristor. At first, a simplified numerical solution of the semiconductor equations is developed to obtain the current amplification factor and the base transit time of each transistor of the thyristor model as a function of the emitter current density. The turn-on recurrence relations governing the evolution of the anode current at different lateral points are then derived by the transit function method. The time constant of the anode current rise and the plasma spreading velocity are calculated as functions of the anode current density. The results of simulation are in close agreement with the corresponding measured values of plasma spreading velocity by the electrical probes method. This agreement confirms the validity of our model over a large scale of anode current densities 相似文献
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Bahran N. A. El-Shafai W. Zekry A. El-Rabaie S. El-Halawany M. M. El-Samie F. E. Abd 《Multimedia Tools and Applications》2019,78(16):22351-22396
Multimedia Tools and Applications - In the Three-Dimensional H.264 Multi-view Video Coding (3D H.264/MVC), the original 3D Video (3DV) sequence is a combination of variable video frames captured... 相似文献
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In this paper, a new microthyristor structure suitable for microelectronics applications has been introduced. A suitable technology for its implementation has been chosen. The microthyristor has been designed and its performance has been simulated. The device showed superior performance concerning the switching times and the power dissipation in addition to controllability of its S-curve. During the development of this work, we introduced some new concepts such as doping-engineered devices, thyristor turn-off by shunting its cathode junction, and power consumption reduction by realizing high resistances. The basic requirements and some conditions are put together for successful launch of the microthyristor in microelectronics. 相似文献
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