Metal-insulator-metal (MIM) capacitors are used for analog, RF, and DRAM applications in ICs. The International Technology Roadmap for Semiconductors (ITRS) specifies continuing increase in capacitance density (> 7 fF/ m2), lower leakage current density (< 10 8 A/cm2), very low effective oxide thickness (EOT < 1 nm, for DRAM applications), and better capacitance density-voltage (C-V) linearity ( < 100 ppm/V2, for analog/RF applications). In addition, the maximum fabrication/processing temper-ature should not be greater than 400 0C, in order to be compatible with the thermal budget of back-end fabrication steps. Low dielectric constants of conventional SiO2 and Si3N4 capacitors limit the capacitance densities of these devices. Although scaling down of dielectric thickness increases the capacitance density, it results in large leakage current density and poor C-V linearity. In this work, the effects of high-k materials (Eu2O3, Gd2O3, TiO2) on the device performance of MIM capacitors are studied. The performance of multi-dielectric stack, and doped-dielectric stack devices are also investigated. The effects of anneal temperature, anneal ambient, anneal mode, and dielectric thickness on device performance are evaluated. C-V, current density-voltage (J-V), and reliability measurements are performed to benchmark the electrical performance, and this is correlated to the structural and material properties of the films through ellipsometry, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) measurements. High-performance MIM capacitors are fabricated by using (RF sputtered) Eu2O3 dielectric. The fabricated devices are subjected to different anneal conditions, to study their device performance. Forming gas (FG) and argon (Ar) annealed devices are shown to have higher capacitance densities (7 fF/ m2jF G), lower leakage current densities (3.2 10 8 A/cm2jAr at -1 V), and higher , compared to oxygen (O2) annealed de-vices ( 100kHz = 193 ppm/V2jO2). The electrical characterization results are correlated with the surface chemical states of the films through XPS measurements. The annealing ambient is shown to alter the surface chemical states, which, in turn, modulate the electrical characteristics. High-density MIM capacitors are fabricated by using (RF sputtered) Gd2O3, and Gd2O3-Eu2O3 stacked dielectrics. The fabricated Gd2O3 capacitors are also subjected to different anneal conditions, to study their device performance. Although Gd2O3 capacitors provide high capacitance density (15 fF/ m2), they suffer from high leakage current density, high , and poor reliability. Therefore, stacked dielectrics of Gd2O3 and Eu2O3 (Gd2O3/Eu2O3 and Eu2O3/Gd2O3) are fabricated to reduce leakage current density, improve , and improve reliability, with only a marginal reduction in capacitance density, compared to Gd2O3 capacitors. Density of defects and barrier/trap heights are extracted for the fabricated capacitors, and correlated with the device characteristics. High-performance MIM capacitors with bilayer dielectric stacks of (ALD-deposited) TiO2-ZrO2, and Si-doped ZrO2 are characterized. Devices with (ALD-deposited) TiO2/ ZrO2/TiO2 (TZT) and AlO-doped TZT stacks are also characterized. The influence of doping on the device performance is studied. The surface chemical states of the deposited films are analyzed by high-resolution XPS. The structural analysis of the samples is performed by XRD measurements, and this is correlated to the electrical characteristics of the devices. Reliability measurements are performed to study the effects of constant voltage and current stress on device performance. High capacitance density (> 45 fF/ m2), low leakage current density (< 5 10 8 A/cm2 at -1 V, for most devices), and sub-nm EOT are achieved. These parameters exceed the ITRS specifications for DRAM storage capacitors.

n-type binary compound semiconductors such as InN, InAs, or In2O3 are especial because the branch-point energy or charge neutrality level lies within the conduction band. Their tendency to form a surface electron accumulation layer prevents the formation of rectifying Schottky contacts. Utilizing a reactive sputtering process in an oxygen-containing atmosphere, we demonstrate Schottky barrier diodes on indium oxide thin films with rectifying properties being sufficient for space charge layer spectroscopy. Conventional non-reactive sputtering resulted in ohmic contacts. We compare the rectification of Pt, Pd, and Au Schottky contacts on In2O3 and discuss temperature-dependent current-voltage characteristics of Pt/In2O3 in detail. The results substantiate the picture of oxygen vacancies being the source of electrons accumulating at the surface, however, the position of the charge neutrality level and/or the prediction of Schottky barrier heights from it are questioned.

No description available.

In real life, immediately after joint replacement, the artificial joint is actually bathed in blood (and clotted blood) instead of synovial fluid. Blood contains large molecules and cells of size ~ 5 to 20 μm suspended in plasma and considered to be a non-Newtonian (pseudoplastic) fluid with density of 1060 Kg/m³ and viscosity ~ 0.01 Pas at shear rates of 3000 s⁻¹ (as obtained in this work). The effect of these properties on friction and lubrication is not fully understood and, so far to our knowledge, hardly any studies have been carried out regarding friction of metal-on-metal bearings with various clearances in the presence of lubricants such as blood or a fluid containing macromolecules such as hyaluronic acid (HA) which is a major component of synovial fluid increasing its viscosity and lubricating properties. In this work, therefore, we have investigated the frictional behaviour of a group of Smith and Nephew Birmingham Hip Resurfacing implants with a nominal diameter of 50mm and diametral clearances in the range ~ 80 μm to 300 μm, in the presence of blood (clotted and whole blood), a combination of bovine serum (BS) with hyaluronic acid (HA) and carboxymethyl cellulose (CMC, as gelling agent) adjusted to a range of viscosities (~0.001-0.2 Pas), and bovine serum with CMC adjusted to a similar range of viscosities. These results suggested that reduced clearance bearings have the potential to generate high friction especially in the presence of blood which is indeed the in vivo lubricant in the early weeks after implantation. Friction factors in higher clearance bearings were found to be lower than those of the lower clearance bearings using blood as the lubricant. Similar trends, i.e. increase in friction factor with reduction in diametral clearance, were found to be also the case using a combination of BS+CMC or BS+HA+CMC as lubricants having viscosities in the range 0.1-0.2 and 0.03-0.14 Pas, respectively. On the other hand, all the lubricants with lower viscosities in the range 0.001-0.0013 and 0.001-0.013 Pas for both BS+CMC and BS+HA+CMC, respectively, showed the opposite effect, i.e. caused an increase in friction factor with increase in diametral clearance. Another six large diameter (50mm nominal) BHR deflected prostheses with various clearances (~ 50-280μm after cup deflection) were friction tested in vitro in the presence of blood and clotted blood to study the effect of cup deflection on friction. It was found that the biological lubricants caused higher friction factors at the lower diametral clearances for blood and clotted blood as clearance decreased from 280μm to 50μm (after deflection). The result of this investigation has suggested strongly that the optimum clearance for the 50 mm diameter MOM BHR implants to be ≥150μm and <235μm when blood lubricant used, so as to avoid high frictions (i.e. avoid friction factors >0.2) and be able to accommodate a mixed lubrication mode and hence lower the risk of micro- or even macro-motion specially immediately after hip implantation. These suggested optimum clearances will also allow for low friction (i.e. friction factors of <0.2-0.07) and reasonable lubrication (dominantly mixed regime) for the likely cup deflection occurring as a result of press-fit fixation.

Dissolution of hydrogen into intermetallic compounds characteristically occurs at interstitial sites, causing little alteration to the base metal substructure but often bringing about substantial electronic and magnetic changes to the material. These hydrogen-induced alterations in the intermetallic hydrides are of interest both on a fundamental research level and in terms of technological applications; however, there exists no general theory as to how and why these alterations arise. The objective of this research is to elucidate to general effect of hydrogen on intermetallic compounds through the study of crystallographic, magnetic and electronic properties. An investigation has been carried out on the properties of three intermetallic compound - hydrogen systems of general formula ZrM₂, where M = V, Cr, Mn. All three compounds reversibly absorbed hydrogen with no change in crystal symmetry: powder diffraction studies showed that hydrogen was accommodated in interstitial sites of the existing metal sublattice via lattice expansion. The measurement of the magnetic properties of these systems was combined with the determination of conductivity and dielectric properties in order to describe the electronic e¤ects of hydrogen absorption. Despite the lack of signi…cant structural alteration in these systems, electron transfer between the metal sublattice and hydrogen may occur, as manifested in the appearance/disappearance of magnetic phenomena and the increase/decrease of electrical conductivity. Whilst the hydrogen addition in ZrM₂-H occurs simply via an expansion of the crystal structure, hydrogen does not act purely as null dilutant - there exist subtle electronic changes connected with the hydriding process as well.

Λόγω των θεωρητικών πλεονεκτημάτων τους, τα συστήματα ισχίου που συνδυάζουν μεταβλητούς αυχένες και μεγάλες κεφαλές απέκτησαν βαθμιαία μεγάλη δημοτικότητα. Όμως, μεταξύ των άλλων, ανησυχίες διατυπώθηκαν για τις αλλαγές που τα συστήματα αυτά επιφέρουν στο πρότυπο των φορτίσεων στο εγγύς μηριαίο. Πράγματι, πρόσφατες αναλύσεις φορτίσεων έδειξαν ότι η χρήση των συναρμολογούμενων αυχένων και των μεγάλων κεφαλών αλλάζει σημαντικά την κατανομή των φορτίων κατά μήκος του μηριαίου. Η αρχική μας υπόθεση είναι ότι οι μεταβολές αυτές επηρεάζουν την πρώιμη άπω μετανάστευση του μηριαίου στυλεού. Εξετάσαμε, κατόπιν, την επίδραση της διαμέτρου της κεφαλής και της γεωμετρίας του αυχένα στην μετανάστευση του στυλεού μετά δύο χρόνια παρακολούθησης σε μια σειρά 116 ασθενών (125 ισχίων), οι οποίοι υποβλήθηκαν σε πρωτογενή ΜοΜ ΟΑΙ με την εγγύς αρθρωτή πρόθεση Profemur®E (Wright Medical Technology Inc., Arlington, TN) συνδυασμένη με κεφαλές μεγάλης διαμέτρου (≥40mm). Βρήκαμε ότι η επιλογή της γεωμετρίας του αυχένα και της διαμέτρου της κεφαλής δεν είχε καμία επίδραση στην μετανάστευση του στυλεού. Μία πολυπαραγοντική ανάλυση παλινδρόμησης που περιέλαβε τους συγχυτικούς παράγοντες του δείκτη μάζας σώματος, της ποιότητας του οστού, της πλήρωσης του αυλού σε διάφορες θέσεις και της θέσης τοποθέτησης του στυλεού απεκάλυψε μόνο μια αρνητική συσχέτιση μεταξύ της καθίζησης και της πλήρωσης του αυλού στο ύψος της μέσης του στυλεού. Η στατιστική ανάλυση δεν επιβεβαίωσε την αρχική μας υπόθεση ότι η επιλογή της γεωμετρίας του αυχένα και/ή της διαμέτρου της κεφαλής επηρεάζει την πρώιμη άπω μετανάστευση του στυλεού. Απεδείχθη όμως η σημασία της σωστής εκτίμησης του μεγέθους του στυλεού. Για να διερευνήσουμε παραπέρα αν τα διαφορετικά πρότυπα φορτίσεων των διαφόρων κατευθύνσεων του αυχένα και των διαφορετικών διαμέτρων της κεφαλής παίζουν κάποιο ρόλο στην αυξημένη συχνότητα χαλάρωσης, σχεδιάσαμε μια ανάλυση πεπερασμένων στοιχείων και χρησιμοποιήσαμε σαν πρότυπο το σύστημα με τον ευθύ αυχένα και την κεφαλή των 28 χιλ. Χρησιμοποιώντας στοιχεία που προήλθαν από αξονικές τομογραφίες, αλλά και τη χρήση μιας σταθερής μετρητικής μηχανής, ένα πτωματικό μηριαίο και ο αρθρωτός στυλεός Profemur®E ψηφιοποιήθηκαν πλήρως, οδηγώντας μέσω του λογισμικού ANSYS Workbench σε ένα τρισδιάστατο μοντέλο πεπερασμένων στοιχείων. Αρχικά, προσδιορίσθηκαν τα φορτία και οι παραμορφώσεις, εστιάζοντας σε ορισμένες περιοχές κατά μήκος του μηριαίου: στο μηριαίο πλήκτρο και στην εξωτερική επιφάνεια κάτω από τον μείζονα τροχαντήρα, στην περιοχή του άκρου του στυλεού, καθώς και κατά μήκος της τραχείας γραμμής. Η ανάλυση των πεπερασμένων στοιχείων απέδειξε ότι η χρήση των μεγάλων κεφαλών προκαλεί σημαντικές αλλαγές στις παραμορφώσεις μέσα στον οστικό όγκο, σε σχέση με το μοντέλο με την κεφαλή των 28 χιλ. Στην εξωτερική επιφάνεια του μηριαίου, κατά μήκος της τραχείας γραμμής και στο άκρο του στυλεού η αύξηση της διαμέτρου οδηγεί σε αύξηση των παραμορφώσεων, ενώ στην περιοχή του μηριαίου πλήκτρου συμβαίνει το αντίθετο. Κατόπιν υπολογίσθηκαν οι μέσες τιμές των παραμορφώσεων για καθεμία από τις 11 γεωμετρίες του αυχένα, εστιάζοντας σε συγκεκριμένες περιοχές ενδιαφέροντος: στην έσω πλευρά του μηριαίου στο μηριαίο πλήκτρο, στην έξω πλευρά στην περιοχή κάτω από τον μείζονα τροχαντήρα, καθώς επίσης στην πρόσθια και οπίσθια επιφάνεια του μηριαίου και σε μια κυκλική περιοχή γύρω από το άκρο του στυλεού. Συγκρινόμενοι με το σύστημα με τον ευθύ αυχένα, ο αυχένας με πρόσθια κλίση 15° έδειξε μια αύξηση 17% και 17.7% στην πρόσθια και οπίσθια επιφάνεια του μηριαίου καιφαίνεται να είναι ο πιο επικίνδυνος. Ο ίδιος αυχένας έδειξε τη μεγαλύτερη αύξηση των παραμορφώσεων στην εξωτερική περιοχή ενδιαφέροντος (13%) και στο μηριαίο πλήκτρο (5%). Στην περιοχή του άκρου του στυλεού η μεγαλύτερη αύξηση καταγράφηκε με τον διπλής γωνίας βλαισό-οπίσθιας κλίσης αυχένα (15.4%), ενώ με τον 15° πρόσθιας κλίσης ήταν 11%. Πιστεύουμε, πάντως, ότι η δημοσιευμένη μεγαλύτερη συχνότητα άσηπτης χαλάρωσης των συγκεκριμένων συστημάτων δεν μπορεί να εξηγηθεί με τα ευρήματα αυτής της μελέτης. Αντίθετα η εξήγηση πρέπει να αναζητηθεί στη βιοδραστικότητα των μεταλλικών ιόντων που παράγονται από τις ΜοΜ συνδέσεις και όχι μόνο στην εμβιομηχανική αυτών των συστημάτων. / Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gained gradually popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads alters significantly the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on- Metal THA with the modular grit-blasted Profemur®E (Wright Medical Technology Inc., Arlington, TN) stem combined with large-diameter heads (≥40mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis didn’t confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed. In order to further investigate whether the different strain distributions of the various neck geometries and head diameters play a role in the increased rate of loosening, we designed a Finite Element Analysis (FEA) and used as reference the loading behavior of the straight-neck system with the 28 mm head. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Firstly, strains and stresses were calculated, focusing on areas of clinical interest: the calcar and below the greater trochanter in the proximal femur, the stem tip region and a profile line along linea aspera. The performed FE analysis revealed that the use of large heads produces significant changes in strain development within the bone volume, with respect to the reference model featuring a typical femoral head of 28mm. In the lateral side, along linea aspera and for the stem tip area increasing the head diameter, results in strain rise, while in the calcar area the opposite is observed. Mean strain values, for each of the 11 available neck geometries were then calculated, focusing on specific regions of interest (ROIs) as a whole: medially the calcar and laterally the area below the greater trochanter, as well as, the anterior and the posterior surfaces of the femur and a circumferential area around the stem tip. Compared with the straight neck system, the 15° anteverted neck system showed an increase of 17% and 17.7% in the mean strain developed at the anterior and posterior ROIs respectively and seems to be the most precarious. The same neck showed the greatest strain increase also at the lateral ROI (13%) and at the calcar (5%). At the stem tip the greatest increase was recorded with the double-angled valgus-retroverted neck (15.4%), while for the 15° anteverted neck was 11%. We believe, however, that the reported higher incidence of aseptic loosening of modular-neck stems cannot be confirmed only by the findings of this study. Instead, the explanation should be sought also in the bioreactivity of the metal ions generated by the metal-on-metal junctions and not in the biomechanics of these systems alone.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 162-169).

Die exzellenten Eigenschaften einer Keramik beziehen sich auf den hohen Schmelzpunkt, die gute Hochtemperaturfestigkeit sowie hohe Elastizitätsmodul- und Härtewerte. Weiterhin zeichnen sich die anorganisch-nichtmetallischen Werkstoffebesonders durch ihre gute Korrosions- und Verschleißbeständigkeit aus.Bedingt durch die erschwerte Versetzungsbewegung weisen keramische Werkstoffeeine höhere Sprödigkeit auf. Metallische Werkstoffedagegen sind in der Regel duktil und zeigen meist ein duktiles Bruchverhalten. Lokale Spannungsspitzen können durch plastische Verformung abgebaut werden.Das Ziel dieser Arbeit ist es, das grundsätzlich unterschiedliche Werkstofferhalten einer Keramik und eines Metalls miteinander zu kombinieren, um die Bruchzähigkeit des Keramik-Metall-Verbundwerkstoffes zu erhöhenDie fein verteilten Metalle sollen die Rissausbreitung behindern. Es können unterschiedliche Mechanismen wirken. Im Vergleich zur unverstärkten Keramik ist eine höhere Bruchenergie aufzubringen, um den Riss voran zu treiben. Die Erhöhung der Bruchenergie spiegelt sich in einer höheren Bruchzähigkeit wieder.Um eine duktile Phase in einer spröden Zirkoniumdioxidmatrix zu erzeugen, werden für die Untersuchungen unterschiedliche Metalle eingebracht. Dadurch soll die Bruchzähigkeit als Schadenstoleranz gegenüber dem Totalversagen erhöht werden. Die resultierenden Eigenschaften der Keramik-Metall-Verbundwerkstoffewerden analysiert und charakterisiert.Die Untersuchungen umfassen das pulvermetallurgische Einbringen von metallischen Pulvern mit verschiedenen Teilchengrößen sowie die chemische Einbringung von Präkursoren, die in nanokristalline Metallpartikel umgewandelt werden. Dabei kommen verschiedene Metalle mit unterschiedlichen Wechselwirkungen und Spannungen durch thermische Fehlpassungen in der Matrix zur Anwendung. Zusätzlich wird die Auswirkung der Variation der Verstärkungsform (Partikel/Faser) und des Metallgehaltes untersucht.

Ziel des BMWi-Fördervorhabens 1501393 ist es, durch den Einsatz von Untersuchungsmethoden auf der nm-Skala einen Beitrag zur Aufklärung von Flusseffekten und von Late-Blooming-Effekten in bestrahlten RDB-Stählen zu leisten. Zur Untersuchung dieser Effekte wurde auf RDB-Stähle deutscher Reaktoren aus zwei bei der AREVA GmbH abgeschlossenen Vorhaben zurückgegriffen. Die Auswahl der Grundwerkstoffe und Schweißgüter erfolgte so, dass sich optimale Voraussetzungen für das Erreichen des Gesamtziels des Vorhabens ergeben. Die ausgewählten Untersuchungsmethoden umfassen mit der Neutronenkleinwinkelstreuung, der Atomsondentomographie und der Positronen-annihilationsspektroskopie solche Techniken, die die nm-skaligen bestrahlungsinduzierten Defekt-Fremdatom-Cluster bestmöglich und in komplementärer Weise zu detektieren und zu charakterisieren gestatten. Es wurde ein Flusseffekt auf die Größe der bestrahlungsinduzierten Fremdatomcluster, jedoch nicht auf den Volumenanteil und die mechanischen Eigenschaften gefunden. In einem Cu-armen RDB-Schweißgut wurde ein Late-Blooming-Effekt nachgewiesen, der sich in einem steilen Anstieg des Clustervolumenanteils und der Übergangstemperaturverschiebung nach einer Phase schwacher oder fehlender Zunahme niederschlägt. The BMWi project 1501393 aimed at contributing to the clarification of flux effects and late blooming effects in irradiated RPV steels by means of experimental techniques of sensitivity at the nm scale. The investigation of these effects was focussed on RPV steels, both base metal and weld of German reactors selected according to the objectives of the present project from two previous projects performed at AREVA GmbH. The complementary techniques of small-angle neutron scattering, atom probe tomography and positron annihilation spectroscopy were applied to detect and characterize the irradiation-induced nm-scale defect-solute clusters. A flux effect on the size of the irradiation-induced clusters but no flux effect on both cluster volume fraction and mechanical properties was found. For a low-Cu RPV weld, a late blooming effect was observed, which results in a steep slope of both cluster volume fraction and transition temperature shift after an initial stage of small or no change.

The ever increasing advancements in semiconductor technology and continuous scaling of CMOS devices mandate the need for new dielectric materials with low-k values. The interconnect delay can be reduced not only by the resistance of the conductor but also by decreasing the capacitance of dielectric layer. Also cross-talk is a major issue faced by semiconductor industry due to high value of k of the inter-dielectric layer (IDL) in a multilevel wiring scheme in Si ultra large scale integrated circuit (ULSI) devices. In order to reduce the time delay, it is necessary to introduce a wiring metal with low resistivity and a high quality insulating film with a low dielectric constant which leads to a reduction of the wiring capacitance. Boron carbon nitride (BCN) films are prepared by reactive magnetron sputtering from a B4C target and deposited to make metal-insulator-metal (MIM) sandwich structures using aluminum as the top and bottom electrodes. BCN films are deposited at various N2/Ar gas flow ratios, substrate temperatures and process pressures. The electrical characterization of the MIM devices includes capacitance vs. voltage (C-V), current vs voltage, and breakdown voltage characteristics. The above characterizations are performed as a function of deposition parameters.