Abstract The main objective of this research is studying the effect laser parameters on the linear energy absorption mechanism of laser produced plasma in under critical density zone as a result of high power laser incidence. The work is based on a model designed for CO2 laser which was improved in other studies to include different wavelength considering the type of the plasma material. The results have shown that the total absorbed laser energy per unit length increases with the increase of the laser power, the focal laser of the beam, the atomic number of the plasma material and the laser pulse duration, and decreases according to the increase of the wavelength of the laser light moreover there is an optimum angle in which the laser energy per length unit has its maximum magnitude.
عز الدين الهاشمي للاموج (2015)

تم في هذا البحث دراسة بعض الخصائص الكهربية و البصرية لسطح السليكون المتعدد البلورات(Poly-Crystalline Silicon) وذلك بعد معالجته بنبضات ليزر الياقوت (λ = 6943 A°, τ = 500 μsec., E ≈ 0.58 J/cm²) و بإستخدام تحليل نظري من خلال برنامج حاسوب تم حساب درجة حرارة سطح السليكون كمؤشر لتقدير طاقة النبضة الليزرية التي يمكن إستعمالها في معالجة السطح. أستخدمت مطيافة الأشعة تحت الحمراء (IR-Spectrophotometery) لتقصي ما يحدث من أكسدة على السطح. بزيادة كثافة طاقة النبضة الليزرية تم تتبع التشويه الناتج على سطح و مايحدث من إنصهار و تبخر و إمكانية إحداث ثقوب في شريحة السليكون عند معاملته بنبضة ليزرية بكثافة طاقة (E ≈ 1>7 J/cm²) و مدى إعتماد تجانس الثقب الناتج على موضعه بالنسبة لحدود الحبيبات (Grain Boundaries) على السطح. ولدراسة مدى إمكانية تحسن مواصفات سطح السليكون المعالج بالليزر تم تحضير نوعين من العينات على نفس الشريحة نصفها معالج بالليزر و النصف الأخر غير معالج و ذلك لغرض المقارنة. و تم تحضير ثنائيات شوتكي (Al-Si(poly)-Al) بتسيب طبقة من الألومنيوم على سطح الأمامي و الخلفي للسيلكون بإستخدام التبخير الحراري (Thermal Evaporation) مع إستخدام نبضة ليزر الياقوت بكثافة طاقة (E ≈ 1.0 J/cm²) لصنع الوصلة الأومية (Ohmic Contact) وذلك بدلا من إيتخدام التسخين الحراري التقليدي. ثم قياس الخصائص الكهربية لهذه الثنائيات و هي [Ideality Factor(n), Barrier Height (ϕв), Reverse Saturation Current (Js)] و مقارنتها بثنائيات شوتكي المصنعة على سطح الغير معالج ليزريا التي تعمل كحاجز إلكتروستاتيكي لحاملات الشحن الأقلية (Minority Charge Carriers) مما يؤدي الي زيادة تيار التشبع العكسي و البتالي تقل كفاءة ثنائيات شوتكي المصنعة على هذا السطح. أخيرا يمكن إستخدام نبضة ليزر الياقوت ذو الطاقة العالية في عملية ثقب شريحة السليكون المتعدد البلورات و مدى تجانس الثقب الحادث يحدده موضعه بالنسبة لحدود الحبيبات فكلما بعدت الثقوب عن مناطق حدود الحبيبات كلما كانت أكثر تناسقا في الشكل. Abstract In this work, the poly-crystalline silicon surface was mechanically polished, chemically cleaned and then treated with ruby laser (λ = 6943 A°, τ = 500 μsec., E ≈ 0.58 J/cm²) of energy density from 0.58 J/cm2 . The temperature profile of the treated surface was estimated using numerical analysis of the heat flow equation. IR-spectra is used to diagnose the treated surface for any oxidation. Laser pulse of energy density higher than 0.58 J/cm20 caused a damage on the surface. The energy density of 1.7 J/cm2 resulted in small holes in poly-Si wafers, the homogeneousity of the hole shape depends on its relative position with respect to the grain boundaries. Al-Si(poly)-Al Schottky diodes were prepared on laser treated surface, and compared with those prepared on the untreated one. The diode’s parameters, such as, ideality factor n, barrier height ϕв, and reverse saturation current Js, were determined and discussed. Generally, it was found that the laser treatment of poly-Si surface improved the schottky diode parameters.
طارق عاشور (1996)

Abstract In practice, most SoCs are multiprocessor systems-on-chips (MPSoCs) because it is too difficult to design a complex system-on-chip without making use of multiple CPUs. MPSoCs are the latest picture of very large scale integration (VLSI) technology. The architecture of the system is generally tailored to the application rather than being a general-purpose chip. This in turn enforces designers to move beyond logic design into advanced computer architecture and parallel processing. In such architectures, cores are integrated via a custom or commercial interconnection network with a controller, timing and a function interface to the external world. Current state-of-the-art SoCs already embeds typical sub-systems such as digital signal processors (DSP), RAM, ROM, MPEG cores.The main goal of this thesis is to design an efficient switch for Fat-tree interconnection networks. In addition a useful survey study for interconnection networks architectures, technologies and routing algorithms was provided. The survey included in some details commonly used switching methods and virtual channel arrangements. The proposed switch structure has been validated by a software model.A set of algorithms and procedures have been developed to facilitate the switch functionality. Those procedures include the control of transmission of the packets from switch input buffer to switch output buffer and transferring packets from switch output buffer to neighboring switch input buffer. While the input/output link controllers take care of buffer assignments to flits (packet) and deals with buffer organization. More over, the algorithms include (i) the routing algorithm which is the least common ancestor routing algorithm, (ii) arbitration algorithm that based on round-robin technique.Therefore in this thesis we have proved the correctness of the functionality of the proposed switch in software model that have been written in C++ language. The obtained simulation results of the switch functionality in fat-tree of 16 nodes definitely declare the correctness of the proposed arbitration scheme as well as showing the efficiency of the routing algorithm. Finally, we can say that the fat-tree interconnection network is very good candidate to implement future NoC connectivity for current and future multiprocessor systems-on-chips (MPSoCs) designs due to its modular, flexible and regular structured design. In turn, these features are suitable as well for VLSI realizations.
أسماء شعبان العصار (2010)