78 research outputs found

    Solid State Circuits Technologies

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    The evolution of solid-state circuit technology has a long history within a relatively short period of time. This technology has lead to the modern information society that connects us and tools, a large market, and many types of products and applications. The solid-state circuit technology continuously evolves via breakthroughs and improvements every year. This book is devoted to review and present novel approaches for some of the main issues involved in this exciting and vigorous technology. The book is composed of 22 chapters, written by authors coming from 30 different institutions located in 12 different countries throughout the Americas, Asia and Europe. Thus, reflecting the wide international contribution to the book. The broad range of subjects presented in the book offers a general overview of the main issues in modern solid-state circuit technology. Furthermore, the book offers an in depth analysis on specific subjects for specialists. We believe the book is of great scientific and educational value for many readers. I am profoundly indebted to the support provided by all of those involved in the work. First and foremost I would like to acknowledge and thank the authors who worked hard and generously agreed to share their results and knowledge. Second I would like to express my gratitude to the Intech team that invited me to edit the book and give me their full support and a fruitful experience while working together to combine this book

    Resistive switching in ferroelectric polycrystalline Yttrium Manganese Oxide thin films

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    A memristor is a two-terminal device which exhibits a hysteresis loop in the current-voltage characteristics. Resistive switching refers to reversible non-volatile change in state of the resistance. There exists a wide range of materials which show resistive switching i.e, phase change materials are used in today’s technology which are a main component of the resistive random access memory. In actual research, mostly metal oxides are investigated regarding their resistive switching which is based on migration of anions and cations. Additionally, in hexagonal manganites, h-RMnO3 (R = Y, In, Sc, Ho,...,Lu), the multiferroic properties and nano-sized conducting domain walls introduce further interesting aspects in this material class which may contribute to additional features in resistive switching. This dissertation investigates the resistive switching in yttrium manganite thin film (Y1Mn1O3, Y0.95Mn1.05O3, Y1Mn0.99Ti0.01O3 and Y0.94Mn1.05Ti0.01O3) based metal-insulator-metal structures with different top electrodes (Au or Al) and bottom electrodes (Pt or Pt/Ti or Pt/Cr) in 2-point DC probe measurements. Yttrium manganite thin films have been deposited by pulsed laser deposition on metal coated SiO2/Si substrates. Electrical characterization of yttrium manganite thin films in a metal-insulator-metal structure exhibit electroforming-free unipolar resistive switching. High voltages and currents are required for SET (V_ ) and RESET (I_ ), respectively. The observed resistive switching is assigned to the formation (low resistance state) and rupture (high resistance state) of conductive, metallic-like filaments induced by a thermo-chemical phenomena. Observed unipolar RS is classified as the thermo-chemical memory (TCM) resistive switching phenomena related to the locally increased temperature. The stability of conductive filaments leads to good retention of the programmed states with large memory window (OFF to ON resistance in the order of 10^4 - 10^6, depends on electrodes, electrode size and composition of yttrium manganite thin films). The endurance or number of loading cycles of the resistive switching devices are improved and is in the order of 10^3 for Y1Mn1O3 and Y0.95Mn1.05O3 composition with Al-top electrodes and Pt-bottom electrode. The maximum number of loading cycles is observed for an applied negative bias, a preferential negative polarity for switching the yttrium manganite thin film devices with Au or Al top electrodes and Pt or Pt/Ti bottom electrodes. Whereas, yttrium manganite thin film devices with Pt/Cr-bottom electrode and Al-top electrodes a preferential positive bias is required for switching the devices. Temperature-dependent measurements of yttrium manganite thin films deposited on Pt/SiO2/Si show semiconducting and metallic-like conduction in high resistance state and low resistance state, respectively. The activation energy () extracted in the ohmic region for hopping of holes localized at Mn4+ is in the range of 0.36 eV - 0.43 eV. Scanning electron microscopy in secondary electron emission mode with an in-lens detector and a small acceleration voltage of 1.0 kV is used to characterize the ferroelectric charged domain network formation in polycrystalline hexagonal yttrium manganite thin film. The observed bright regions correspond to local polarization vector with upward polarization components (+P ) and dark regions to local polarization vector with downward polarization components (-P ). A dense domain network is observed for Mn-rich samples (Y0.95Mn1.05O3 and Y0.94Mn1.05Ti0.01O3) in comparison to Y1Mn1O3 and Y1Mn0.99Ti0.01O3 with smaller grains show isolated charged domains. The observed dependency of different compositions to the charged domain density network in yttrium manganite thin films may influenced by different factors: stoichiometry gradient, oxygen, dopant concentration and the resulting grain structure.Ein Memristor ist ein Bauelement, welches eine Hysterese beim Vermessen seiner IU-Kennlinie aufweist. Dieses als „Widerstandsschalten“ bezeichnete Phänomen beruht auf der nichtflüchtigen Veränderung des Widerstandes. Es existiert eine breite Auswahl an Materialien, welche Widerstandsschalten zeigen, z.B. sind Phasenwechselmaterialien die Hauptkomponenten in aktuellen RRAMs. Aktuelle werden hauptsächlich Metalloxide untersucht, welche durch Migration von Anionen und Kationen Widerstandsschalten hervorrufen. Weitere Materialien wie hexagonale Manganoxidverbindungen RMnO3 (R = Y, In, Sc, Ho,...,Lu), besitzen zusätzliche multiferroische Eigenschaften, bei denen geladene Domänengrenzen weitere interessante Aspekte in dieser Materialklasse einführen und das Widerstandsschalten beeinflussen können. Die vorliegende Dissertation untersucht das Widerstandsschalten in Yttriummanganoxid-Dünnfilmen mit unterschiedlichen Kompositionen und unterschiedlichen Elektrodenmaterialien. Y1Mn1O3, Y0.95Mn1.05O3, Y1Mn0.99Ti0.01O3 und Y0.94Mn1.05Ti0.01O3, wurden mittels gepulster Laserdeposition auf metallisierte Si/SiO2 Substrate abgeschieden. Die elektrische Charakterisierung von Yttriummanganoxid-Dünnfilmen in einer Metall-Isolator-Metall Sandwichstruktur weist auf elektroformierungsfreies, unipolares Widerstandsschalten hin. Das beobachtete Widerstandsschalten wird auf die Formierung (niederohmiger Zustand) und Zerstörung (hochohmiger Zustand) des leitfähigen, metallischen Filaments (geladenen Domänengrenzen oder auch Vortices), verursacht durch thermisch-chemische Vorgänge, zurückgeführt. Die geladenen Domänengrenzen und/oder Vortices in Yttriummanganoxid-Dünnfilmen beeinflussen unter Umständen als nanoskalige Objekte die Formierung der leitfähigen Filamente. Die Stabilität der leitfähigen Filamente führt zu einer guten Langzeitspeicherung der programmierten Zustände, welche auch ein sehr großes Speicherfenster (Widerstandsverhältnis zwischen Aus/An-Zustand von 10^5) aufweisen. Die großen Widerstandsverhältnisse sind z.B. für die Herstellung von Auswahlschaltern (selektoren) in Crossbar-Strukturen notwendig, um die möglicherweise auftretenden Kriechströme in Crossbar-Strukturen zu unterdrücken, welche sonst Lesefehler der adressierten Zellen hervorrufen würden. Die Wiederbeschreibbarkeit ist in der Größenordnung von ca. 10^3, abhängig von der chemischen Zusammensetzung des Yttriummanganoxide-Dünnfilmes und vom verwendeten Elektrodenmaterial. Resultate der Charakterisierung mittels Rasterelektronenmikroskopie im Sekundärelektronenmodus mit einer kleinen Beschleunigungsspannung von 1.0 kV weisen auf geladene ferroelektrische Domänen in polykristallinem hexagonalen YMnO3 Dünnfilmen hin. Deswegen muß der Einfluss von geladenen Domänengrenzen und multiferroischen Vortices auf das beobachtete Widerstandsschalten in hexagonalem YMnO3 berücksichtigt werden

    Investigations of small-scale magnetic features on the solar surface

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    Solar activity is controlled by the magnetic field, which also causes the variability of the solar irradiance that in turn is thought to influence the climate on Earth. The magnetic field manifests itself in the form of structures of largely different sizes. This thesis concentrates on two types of the smallest known magnetic features: The first part studies the properties of umbral dots, dot-like bright features in the dark umbra of a sunspot. The obtained umbral dot properties provide a remarkable confirmation of the results of recent magneto-hydrodynamical simulations. Observations as well as simulations show that umbral dots differ from their surroundings mainly in the lowest photospheric layers, where the temperature is enhanced and the magnetic field is weakened. In addition, the interior of the umbral dots displays strong upflow velocities which are surrounded by weak downflows. This qualitative agreement further strengthens the interpretation of umbral dots as localized columns of overturning convection. The second part of the thesis investigates bright points, which are small-scale brightness enhancements in the darker intergranular lanes of the quiet Sun produced by magnetic flux concentrations. Observational data obtained by the balloon-borne solar telescope SUNRISE are used in this thesis. For the first time contrasts of bright points in the important ultraviolet spectral range are determined. A comparison of observational data with magneto-hydrodynamical simulations revealed a close correspondence, but only after effects due to the limited spectral and spatial resolution were carefully included. 98% of the synthetic bright points are found to be associated with a nearly vertical kilo-Gauss field.Comment: PhD thesis, Braunschweig University, 209 pages; ISBN 978-3-942171-73-1, uni-edition GmbH 201

    Special Topics in Information Technology

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    This open access book presents thirteen outstanding doctoral dissertations in Information Technology from the Department of Electronics, Information and Bioengineering, Politecnico di Milano, Italy. Information Technology has always been highly interdisciplinary, as many aspects have to be considered in IT systems. The doctoral studies program in IT at Politecnico di Milano emphasizes this interdisciplinary nature, which is becoming more and more important in recent technological advances, in collaborative projects, and in the education of young researchers. Accordingly, the focus of advanced research is on pursuing a rigorous approach to specific research topics starting from a broad background in various areas of Information Technology, especially Computer Science and Engineering, Electronics, Systems and Control, and Telecommunications. Each year, more than 50 PhDs graduate from the program. This book gathers the outcomes of the thirteen best theses defended in 2019-20 and selected for the IT PhD Award. Each of the authors provides a chapter summarizing his/her findings, including an introduction, description of methods, main achievements and future work on the topic. Hence, the book provides a cutting-edge overview of the latest research trends in Information Technology at Politecnico di Milano, presented in an easy-to-read format that will also appeal to non-specialists

    Advances in Plastic Forming of Metals

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    The forming of metals through plastic deformation comprises a family of methods that produce components through the re-shaping of input stock, oftentimes with little waste. Therefore, forming is one of the most efficient and economical manufacturing process families available. A myriad of forming processes exist in this family. In conjunction with their countless existing successful applications and their relatively low energy requirements, these processes are an indispensable part of our future. However, despite the vast accumulated know-how, research challenges remain, be they related to the forming of new materials (e.g., for light-weight transportation applications), pushing the boundaries of what is doable, reducing the intermediate steps and/or scrap, or further enhancing the environmental friendliness. The purpose of this book is to collect expert views and contributions on the current state-of-the-art of plastic forming, thus highlighting contemporary challenges and offering ideas and solutions

    Nanocristaux pour les mémoires flash (multicouches, métalliques et organisés)

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    Les deux principales limitations des mémoires non-volatiles de type Flash à stockage de charges dans des nanocristaux en silicium sont la faible fenêtre mémoire et la dispersion des caractéristiques électriques due à la dispersion en taille des nanocristaux. Dans cette thèse, plusieurs solutions sont étudiées afin de remédier à ces deux défauts. Afin d'augmenter la fenêtre de programmation, une première approche consiste à augmenter la densité de stockage de charges grâce à l'utilisation d'une double couche de nanocristaux en silicium. Le fonctionnement et les performances électriques de ces dispositifs mémoires sont étudiés puis interprétés grâce à un modèle analytique. Une seconde approche, plus amont, consiste à utiliser des nanocristaux métalliques pour augmenter la quantité de charges piégées dans les nanocristaux. Le dépôt, la passivation et l'intégration de nanocristaux à caractère métallique (Pt, TiN, W) en tant que grille flottante dans un dispositif mémoire sont ainsi réalisés. Enfin, l'organisation bottom-up des nanocristaux est proposée comme une solution à la dispersion des caractéristiques électriques des dispositifs mémoires. Un procédé original de transfert et de gravure d'un masque auto-organisé à base de copolymères diblocs est développé.The two main limitations of Flash nonvolatile memories charge storage in silicon nanocrystals are the small memory window and the dispersion of electrical characteristics due to the size dispersion of nanocrystals. In this thesis, several solutions are studied in order to remedy these defects. In order to increase the programming window, a first approach is to increase the density of charges stored in the device through the use of a double layer of silicon nanocrystals. The operation and electrical performance of these memory devices are studied and interpreted through an analytical model. A second approach, more upstream, is the use of metallic nanocrystals to increase the amount of trapped charges in the nanocrystals. Deposition, passivation and integration of metal nanocrystals (Pt, TiN, W) as a floating gate in a memory device have been realized. Finally, the "bottom-up" organisation of nanocrystals is proposed as a solution to the dispersion of electrical characteristics of memory devices. An original process for transferring a self-organized diblock copolymer mask into a hard mask is developed and used to etch nanocrystals with small size dispersion.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

    Annual Report 2020 - Institute of Ion Beam Physics and Materials Research

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    As for everybody else also for the Institute of Ion Beam Physics and Materials Research (IIM), the COVID-19 pandemic overshadowed the usual scientific life in 2020. Starting in March, home office became the preferred working environment and the typical institute life was disrupted. After a little relaxation during summer and early fall, the situation became again more serious and in early December we had to severely restrict laboratory activities and the user operation of the Ion Beam Center (IBC). For the most part of 2020, user visits were impossible and the services delivered had to be performed hands-off. This led to a significant additional work load on the IBC staff. Thank you very much for your commitment during this difficult period. By now user operation has restarted, but we are still far from business as usual. Most lessons learnt deal with video conference systems, and everybody now has extensive experience in skype, teams, webex, zoom, or any other solution available. Conferences were cancelled, workshops postponed, and seminar or colloquia talks delivered online. Since experimental work was also impeded, maybe 2020 was a good year for writing publications and applying for external funding. In total, 204 articles have been published with an average impact factor of about 7.0, which both mark an all-time high for the Institute. 13 publications from last year are highlighted in this Annual Report to illustrate the wide scientific spectrum of our institute. In addition, 20 new projects funded by EU, DFG, BMWi/AiF and SAB with a total budget of about 5.7 M€ have started. Thank you very much for making this possible. Also, in 2020 there have been a few personalia to be reported. Prof. Dr. Sibylle Gemming has left the HZDR and accepted a professor position at TU Chemnitz. Congratulations! The hence vacant position as the head of department was taken over by PD Dr. Artur Erbe by Oct. 1st. Simultaneously, the department has been renamed to “Nanoelectronics”. Dr. Alina Deac has left the institute in order to dedicate herself to new opportunities at the Dresden High Magnetic Field Laboratory. Dr. Matthias Posselt went to retirement after 36 years at the institute. We thank Matthias for his engagement and wish him all the best for the upcoming period of his life. However, also new equipment has been setup and new laboratories founded. A new 100 kV accelerator is integrated into our low energy ion nanoengineering facility and complements our ion beam technology in the lower energy regime. This setup is particularly suited to perform ion implantation into 2D materials and medium energy ion scattering (MEIS). Finally, we would like to cordially thank all partners, friends, and organizations who supported our progress in 2020. First and foremost we thank the Executive Board of the Helmholtz-Zentrum Dresden-Rossendorf, the Minister of Science and Arts of the Free State of Saxony, and the Ministers of Education and Research, and of Economic Affairs and Energy of the Federal Government of Germany. Many partners from univer¬sities, industry and research institutes all around the world contributed essentially, and play a crucial role for the further development of the institute. Last but not least, the directors would like to thank all members of our institute for their efforts in these very special times and excellent contributions in 2020

    Proceedings of the 5th International Workshop on Reconfigurable Communication-centric Systems on Chip 2010 - ReCoSoC\u2710 - May 17-19, 2010 Karlsruhe, Germany. (KIT Scientific Reports ; 7551)

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    ReCoSoC is intended to be a periodic annual meeting to expose and discuss gathered expertise as well as state of the art research around SoC related topics through plenary invited papers and posters. The workshop aims to provide a prospective view of tomorrow\u27s challenges in the multibillion transistor era, taking into account the emerging techniques and architectures exploring the synergy between flexible on-chip communication and system reconfigurability
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