Radiation resistance of flash memory manufactured in deep-submicron technology

U radu radijaciona otpornost fleš memorija izrañenih u duboko-submikronskoj tehnologiji, razmatra se aktuelan problem pouzdanosti rada elektronskih memorija u uslovima dejstva jonizujućeg zračenja. Rad je aktuelan pošto visoki stepen minijaturizacije komponenata integrisanih u fleš memorije prouzrokovao izuzetnu osetljivost ovog tipa memorija na efekte jonizujućeg zračenja. Efekti jonizujućeg zračenja mogu biti takvi da dovedu do promene memorisanih podataka ili čak do fizičkog uništenja samih komponenata. Rad je teoretskog, eksperimentalnog i numeričkog karaktera. U uvodnim poglavljima se navode osnovni podacio interakciji zračenja sa materijalom, definiše doza zračenja, ukratko prikazuje metoda Monte - Karlo za simulaciju nuklearnih interakcija, daju podaci o tipovima i konstruktivnim rešenjima ispitivanih fleš memorija. U poglavlju u kome se govori o eksperimentu, ukratko su prikazana polja zračenja Instituta za nuklearne nauke Vinča, gde je eksperimentalni deo rada rañen, i definisane energije i doze primenjivanog zračenja. U poglavlju koje sledi dati su rezultati brojnih autora, meñu kojima je bio i autor teze, o radijacionoj otpornosti MOSFETA sa izolovanim gejtom, na kome se u osnovi, bazira funkcionisanje fleš memorija. Nakon toga je data teorija radijacionih efekata na fleš memorije na kojima se nalaze i originalna tumačenja ovih efekata. Na kraju rada su prikazani i prodiskutovani eksperimentalno i numerički dobijeni efekti zračenja na konkretnim fleš memorijama. Rezultati dobijeni realnim i numeričkim eksperimentom su pokazali dobro slaganje, kako meñusobno, tako i sa teoretski očekivanim rezultatima.Dissertation "Radiation Hardness of Flash Memories Fabricated in Deep Submicron Technology" investigates the relevant problem of electronic memory reliability under exposure to ionizing radiation. The dissertation is up-to-date because the high degree of miniaturization of components integrated into flash memories makes this type of memory very sensitive to ionizing radiation. Ionizing radiation effects can cause changes in the stored content or even physical destruction of memory components. The dissertation is theoretical, experimental, and numerical in character. Introductory chapters provide basic information about the interaction of radiation with materials, state the definition of the absorbed dose, describe concisely the Monte Carlo methods for simulating nuclear interactions, and provide data about the types and construction details of the investigated flash memories. The chapter concerned with the experiment gives a short depiction of radiation fields at the Vinča Institute of Nuclear Sciences, where the experimental part was conducted, and defines the energies and doses of utilized radiation. The next chapter provides results by several authors, including the author of the dissertation, on the radiation hardness of MOSFETs with insulated gates, which form the basis of flash memories. The next part of the dissertation deals with the theory of radiation effects in flash memories, including original explanations of these effects. The final part presents and discusses the effects observed experimentally and numerically in specific flash memories. Results from real and numerical experiments are in good agreement, both with one another and with the theoretically anticipated value

Stress distribution in an anisotropy plane field weakened by an elliptical hole

U radu je razmatran utjecaj položaja eliptičnog otvora na stanje naprezanja anizotropne (ortotropne) jednoosno zategnute ploče, izložene statičkom opterećenju. Otvori u strojnim dijelovima predstavljaju karakteristične izvore koncentracije naprezanja. Na raspodjelu naprezanja oko otvora kao izvora koncentracije naprezanja, znatno utječu kako veličina otvora i vrsta materijala, tako i njegov oblik i položaj u odnosu na pravac djelovanja vanjskog opterećenja. Cilj ovog rada je analiza utjecaja eliptičnog otvora, kao izvora koncentracije naprezanja, na raspodjelu naprezanja. Iako se u praksi eliptični otvori rjeđe sreću od kružnih, poznato je da kružni otvori predstavljaju specijalan slučaj eliptičnih i sve jednakosti do kojih se dolazi kod eliptičnih otvora vrijede i za kružne otvore kada se u tim jednakostima poluosi eliptičnog otvora izjednače. U ovom radu razmatrani su samo dijelovi od anizotropnih (ortotropnih) materijala, jer se u praksi pokazalo da isti mogu biti izvanredni konstrukcijski materijali. Za dobivanje rezultata raspodjele naprezanja u ravninskom izotropnom polju oslabljenom otvorima, korištene su analitičke i numeričke metode.In the paper, the influence of an elliptical hole onto stress condition of an anisotropic (orthotropic) one-axis strengthened panel exposed to static loading is considered. Holes in machine parts represent characteristic sources of stress concentration. The stress distribution around the holes, as the source of stress concentration, is significantly influenced not only by the size of a hole and its material but also by its form and position in relation to the course of action of an outer loading. The aim of this paper is the analysis of the elliptical hole influence, as the source of stress concentration, onto stress distribution. Although in practice the elliptical holes are not as common as the circular ones, it is known that the circular holes represent a special case of the elliptical ones, and all equalities being accomplished within elliptical holes are valid within the circular ones, when half-axes of an elliptical hole have been equalled. In this paper, only the parts from anisotropic (orthotropic) materials are considered, since in practice it has been shown that they can be excellent construction materials. The analytical and numerical methods are used for accomplishment of the stress distribution in a plane isotropic field weakened by holes

Radiation effects in polycarbonate capacitors

The aim of this paper is to examine the influence of neutron and gamma irradiation on the dissipation factor and capacitance of capacitors with polycarbonate dielectrics. The operation of capacitors subject to extreme conditions, such as the presence of ionizing radiation fields, is of special concern in military industry and space technology. Results obtained show that the exposure to a mixed neutron and gamma radiation field causes a decrease of capacitance, while the loss tangent remains unchanged

Gamma-ray irradiation and post-irradiation at room and elevated temperature response of pMOS dosimeters with thick gate oxides

Gamma-ray irradiation and post-irradiation response at room and elevated temperature have been studied for radiation sensitive pMOS transistors with gate oxide thickness of 100 and 400 nm, respectively. Their response was followed based on the changes in the threshold voltage shift which was estimated on the basis of transfer characteristics in saturation. The presence of radiation-induced fixed oxide traps and switching traps - which lead to a change in the threshold voltage - was estimated from the sub-threshold I-V curves, using the midgap technique. It was shown that fixed oxide traps have a dominant influence on the change in the threshold voltage shift during gamma-ray irradiation and annealing

Real-time shadows in OpenGL caused by the presence of multiple light sources

U suvremenoj računalnoj grafici naglasak je na detaljima prizora, a uzimajući u obzir poboljšanja hardverskih svojstava, nije dopušteno raditi kompromise kada je riječ o stvarnosti scena. Svaki odraz, sjena, zaobljeni kut ili prozirnost mora biti doveden do savršenstva i prikazan u cilju da se scena koja se oslikava učini što realističnijom. U jednom od najšire rabljenih API-ja za renderiranje 3D objekata, OpenGL-u, ne postoji nešto poput knjižnice za dodavanje ovih pojava koje postoje u stvarnosti. Ako se razmatra mogućnost postojanja više izvora svjetlosti, renderiranje svih ovih detalja postaje pravi izazov. Cilj ovog rada je obezbjeđivanje metoda za generiranje sjene na efikasan način, za objekte često rabljene kao komponente složenih 3D objekata, u uvjetima prisutnosti više svjetlosnih izvora s mogućnošću kretanja.In modern computer graphics, the emphasis is on the details of the scene, and taking into account the improvements in hardware performances, it is not allowed to make compromises when it comes to the reality of scenes. Each reflection, shadow, rounded corner and transparency must be brought to perfection and presented in order to make a depicted scene more realistic. In one of the most widely used API for rendering 3D objects, OpenGL, there is nothing similar to a library for adding those phenomena that exist in reality. If the possibility of existence of multiple light sources is considered, rendering all these details becomes a real challenge. The aim of this paper is to provide a method for generating shadows in an efficient way, for the objects commonly used as components of complex 3D objects, in conditions of the presence of moving light sources

Određivanje temperaturske zavisnosti karakteristika solarnih ćelija merenjima frekventnog šuma i faktora idealnosti

Prilikom procesa detekcije zračenja uticaj temperature i termički indukovan šum u fotodetektorima su veoma značajni. Degradacija električnih i optičkih karakteristika fotodetektora pri povišenim temperaturama su jedan od glavnih ograničavajućih faktora za njihovu upotrebu. S obzirom na to da većina električnih procesa u poluprovodničkim uređajima u manjoj ili većoj meri zavisi od temperature, istraživanja na temperaturama višim od sobne mogu da otkriju moguće promene izlaznih karakteristika uređaja. Sa tehnološkog stanovišta, termički izazvan šum povećava minimalni signal koji može da se detektuje, što je posebno značajno za nisko energetske detektore i detektore nejonizujućeg zračenja. U ovom radu je uticaj povišene temperature proučavan preko merenja frekvetno zavisnog šuma i osnovnih izlaznih karakteristika solarnih ćelija

CONSUMERS BEHAVIOR ON ORGANIC FOOD: EVIDENCE FROM THE REPUBLIC OF SERBIA CONSUMERS BEHAVIOR ON ORGANIC FOOD: EVIDENCE FROM THE REPUBLIC OF SERBIA

Summary In developed countries, the demand for organic food has seen a significant increase in the past decade. Howeve

Analysis of marketing instruments used by domestic organic food producers

The overview of previous research results points out to the fact that the majority of the sources related to the organic food marketing belong to the literature based on the research of consumers, with the lack of extensive research of organic food producers. Thus, the results obtained by the quantitative research of organic food producers on the territory of the Republic of Serbia, are presented in this paper. The main marketing mix instruments (4P) are in the focus of analysis, as the most beneficial way of determining the success of marketing activities of the organic food producers in Serbia. In order to get a comprehensive idea of the success of the market activity of the producers, the obtained results are explained in regard to the theoretical knowledge of consumer behavior, acquired by an extensive overview of the relevant literature. The research results are significant, both for the producers of organic food, as well as for traders, because they indicate the key elements to improve the placement of organic food products originating in Serbia. As an important contribution of the paper to the topic, recommendations for the development of an appropriate marketing strategy are given in the conclusion

Monte Carlo optimization of redundancy of nanotechnology computer memories in the conditions of background radiation

The aim of this paper is applying statistical laws and enlargement law to determine a redundancy level of nanotechnology computers with a pre-given statistical confidence. We have tested radiation hardness of MOS memory components (commercial EPROM memory) using both Monte Carlo simulation method and experimental procedure. Then, by using the statistical enlargement law, we have performed the analysis of redundancy optimization of MOS structure for nanotechnology computers, under the influence of background radiation, and obtained more than satisfying results. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 171007

Reliability of semiconductor and gas-filled diodes for over-voltage protection exposed to ionizing radiation

The wide-spread use of semiconductor and gas-filled diodes for non-linear over-voltage protection results in a variety of possible working conditions. It is therefore essential to have a thorough insight into their reliability in exploitation environments which imply exposure to ionizing radiation. The aim of this paper is to investigate the influence of irradiation on over-voltage diode characteristics by exposing the diodes to californium-252 combined neutron/gamma radiation field. The irradiation of semiconductor over-voltage diodes causes severe degradation of their protection characteristics. On the other hand, gas-filled over-voltage diodes exhibit a temporal improvement of performance. The results are presented with the accompanying theoretical interpretations of the observed changes in over-voltage diode behaviour, based on the interaction of radiation with materials constituting the diodes