A III-V channel field effect transistor for non-classical CMOS: process optimisation for improved gate stack function

This thesis describes a collection of studies into the electrical response of a III-V MOS stack comprising metal/GaGdO/GaAs layers as a function of fabrication process variables and the findings of those studies. As a result of this work, areas of improvement in the gate process module of a III-V heterostructure MOSFET were identified. Compared to traditional bulk silicon MOSFET design, one featuring a III-V channel heterostructure with a high-dielectric-constant oxide as the gate insulator provides numerous benefits, for example: the insulator can be made thicker for the same capacitance, the operating voltage can be made lower for the same current output, and improved output characteristics can be achieved without reducing the channel length further. It is known that transistors composed of III-V materials are most susceptible to damage induced by radiation and plasma processing. These devices utilise sub-10 nm gate dielectric films, which are prone to contamination, degradation and damage. Therefore, throughout the course of this work, process damage and contamination issues, as well as various techniques to mitigate or prevent those have been investigated through comparative studies of III-V MOS capacitors and transistors comprising various forms of metal gates, various thicknesses of GaGdO dielectric, and a number of GaAs-based semiconductor layer structures. Transistors which were fabricated before this work commenced, showed problems with threshold voltage control. Specifically, MOSFETs designed for normally-off (VTH > 0) operation exhibited below-zero threshold voltages. With the results obtained during this work, it was possible to gain an understanding of why the transistor threshold voltage shifts as the gate length decreases and of what pulls the threshold voltage downwards preventing normally-off device operation. Two main culprits for the negative VTH shift were found. The first was radiation damage induced by the gate metal deposition process, which can be prevented by slowing down the deposition rate. The second was the layer of gold added on top of platinum in the gate metal stack which reduces the effective work function of the whole gate due to its electronegativity properties. Since the device was designed for a platinum-only gate, this could explain the below zero VTH. This could be prevented either by using a platinum-only gate, or by matching the layer structure design and the actual gate metal used for the future devices. Post-metallisation thermal anneal was shown to mitigate both these effects. However, if post-metallisation annealing is used, care should be taken to ensure it is performed before the ohmic contacts are formed as the thermal treatment was shown to degrade the source/drain contacts. In addition, the programme of studies this thesis describes, also found that if the gate contact is deposited before the source/drain contacts, it causes a shift in threshold voltage towards negative values as the gate length decreases, because the ohmic contact anneal process affects the properties of the underlying material differently depending on whether it is covered with the gate metal or not. In terms of surface contamination; this work found that it causes device-to-device parameter variation, and a plasma clean is therefore essential. This work also demonstrated that the parasitic capacitances in the system, namely the contact periphery dependent gate-ohmic capacitance, plays a significant role in the total gate capacitance. This is true to such an extent that reducing the distance between the gate and the source/drain ohmic contacts in the device would help with shifting the threshold voltages closely towards the designed values. The findings made available by the collection of experiments performed for this work have two major applications. Firstly, these findings provide useful data in the study of the possible phenomena taking place inside the metal/GaGdO/GaAs layers and interfaces as the result of chemical processes applied to it. In addition, these findings allow recommendations as to how to best approach fabrication of devices utilising these layers.

Roland Anhorn / Frank Bettinger / Cornelis Horlacher / Kerstin Rathgeb (Hrsg.): Kritik der Sozialen Arbeit ��� kritische Soziale Arbeit. Wiesbaden: Springer VS Verlag f��r Sozialwissenschaften 2012 (480 S.) [Rezension]

Rezension von: Roland Anhorn / Frank Bettinger / Cornelis Horlacher / Kerstin Rathgeb (Hrsg.): Kritik der Sozialen Arbeit ��� kritische Soziale Arbeit. Wiesbaden: Springer VS Verlag f��r Sozialwissenschaften 2012 (480 S.; ISBN 978-3-531-17917-9)

Classical Invariants for Principal Series and Isomorphisms of Root Data

We develop some new techniques to calculate the Schur indicator for self-dual irreducible Langlands quotients of the principal series representations. Using these techniques we derive some new formulas for the Schur indicator and the real-quaternionic indicator. We make progress towards developing an algorithm to decide whether or not two root data are isomorphic. When the derived group has cyclic center, we solve the isomorphism problem completely. An immediate consequence is a clean and precise classification theorem for connected complex reductive groups whose derived groups have cyclic center.

Classical and quantum approaches to the interaction of light and matter at the nanoscale

168 p.

A natural extension of the classical envelope theorem in vector differential programming

The aim of this paper is to extend the classical envelope theorem from scalar to vector differential programming. The obtained result allows us to measure the quantitative behaviour of a certain set of optimal values (not necessarily a singleton) characterized to become minimum when the objective function is composed with a positive function, according to changes of any of the parameters which appear in the constraints. We show that the sensitivity of the program depends on a Lagrange multiplier and its sensitivity.

Classical electrodynamics: retarded potentials and power emission by accelerated charges

L'obiettivo di questo lavoro �� quello di analizzare la potenza emessa da una carica elettrica accelerata. Saranno studiati due casi speciali: accelerazione lineare e accelerazione circolare. Queste sono le configurazioni pi�� frequenti e semplici da realizzare. Il primo passo consiste nel trovare un'espressione per il campo elettrico e il campo magnetico generati dalla carica. Questo sar�� reso possibile dallo studio della distribuzione di carica di una sorgente puntiforme e dei potenziali che la descrivono. Nel passo successivo verr�� calcolato il vettore di Poynting per una tale carica. Useremo questo risultato per trovare la potenza elettromagnetica irradiata totale integrando su tutte le direzioni di emissione. Nell'ultimo capitolo, infine, faremo uso di tutto ci�� che �� stato precedentemente trovato per studiare la potenza emessa da cariche negli acceleratori.

Defining ����vara: A New Perspective in the Hermeneutics of Classical Yoga

The mere presence of the term ����vara in Pata��jali���s Yogas��tra has come to affect the meaning of both the path and the goal of Classical Yoga as well as the meaning of the term Yoga itself. The frequent translation of the term ����vara as God leads to the system of Classical Yoga to be labeled as theistic, particularly obscuring the interpretation of ����varapra���idh��na, a functional component of the system, as well as perpetuating a syncretic trend that has led to the popular understanding of Yoga as ���union with the divine���. From identifying problematic hermeneutical trends and their underlying causes, as well as understanding the term within the constraints of the original text in its original Sanskrit, the term ����vara emerges as the archetype of an ultimate reality functioning as a practical and experiential tool providing the yogi with a direct glimpse of its true nature.

A non-classical LysR-type transcriptional regulator PA2206 is required for an effective oxidative stress response in Pseudomonas aeruginosa

LysR-type transcriptional regulators (LTTRs) are emerging as key circuit components in regulating microbial stress responses and are implicated in modulating oxidative stress in the human opportunistic pathogen Pseudomonas aeruginosa. The oxidative stress response encapsulates several strategies to overcome the deleterious effects of reactive oxygen species. However, many of the regulatory components and associated molecular mechanisms underpinning this key adaptive response remain to be characterised. Comparative analysis of publically available transcriptomic datasets led to the identification of a novel LTTR, PA2206, whose expression was altered in response to a range of host signals in addition to oxidative stress. PA2206 was found to be required for tolerance to H2O2 in vitro and lethality in vivo in the Zebrafish embryo model of infection. Transcriptomic analysis in the presence of H2O2 showed that PA2206 altered the expression of 58 genes, including a large repertoire of oxidative stress and iron responsive genes, independent of the master regulator of oxidative stress, OxyR. Contrary to the classic mechanism of LysR regulation, PA2206 did not autoregulate its own expression and did not influence expression of adjacent or divergently transcribed genes. The PA2214-15 operon was identified as a direct target of PA2206 with truncated promoter fragments revealing binding to the 5'-ATTGCCTGGGGTTAT-3' LysR box adjacent to the predicted -35 region. PA2206 also interacted with the pvdS promoter suggesting a global dimension to the PA2206 regulon, and suggests PA2206 is an important regulatory component of P. aeruginosa adaptation during oxidative stress.

Synthesis and characterization of K2Ca5(SO4)6�� H2O, the equivalent of g��rgeyite, a rare evaporite mineral

G��rgeyite, K2Ca5(SO4)6����H2O, is a very rare monoclinic double salt found in evaporites related to the slightly more common mineral syngenite. At 1 atmosphere with increasing external temperature from 25 to 150 ��C, the following succession of minerals was formed: first gypsum and K2O, followed at 100 ��C by g��rgeyite. Changes in concentration at 150 ��C due to evaporation resulted in the formation of syngenite and finally arcanite. Under hydrothermal conditions, the succession is syngenite at 50 ��C, followed by g��rgyeite at 100 and 150 ��C. Increasing the synthesis time at 100 ��C and 1 atmosphere showed that initially gypsum was formed, later being replaced by g��rgeyite. Finally g��rgeyite was replaced by syngenite, indicating that g��rgeyite is a metastable phase under these conditions. Under hydrothermal conditions, syngenite plus a small amount of gypsum was formed, after two days being replaced by g��rgeyite. No further changes were observed with increasing time. Pure g��rgeyite showed elongated crystals approximately 500 to 1000 �� m in length. The infrared and Raman spectra are mainly showing the vibrational modes of the sulfate groups and the crystal water (structural water). Water is characterized by OH-stretching modes at 3526 and 3577 cm���1 , OH-bending modes at 1615 and 1647 cm���1 , and an OH-libration mode at 876 cm���1 . The sulfate 1 mode is weak in the infrared but showed strong bands at 1005 and 1013 cm���1 in the Raman spectrum. The 2 mode also showed strong bands in the Raman spectrum at 433, 440, 457, and 480 cm���1 . The 3 mode is characterized by a complex set of bands in both infrared and Raman spectra around 1150 cm���1 , whereas 4 is found at 650 cm���1.

On Ordinal VC-Dimension and Some Notions of Complexity

We generalize the classical notion of Vapnik���Chernovenkis (VC) dimension to ordinal VC-dimension, in the context of logical learning paradigms. Logical learning paradigms encompass the numerical learning paradigms commonly studied in Inductive Inference. A logical learning paradigm is defined as a set W of structures over some vocabulary, and a set D of first-order formulas that represent data. The sets of models of �� in W, where �� varies over D, generate a natural topology W over W. We show that if D is closed under boolean operators, then the notion of ordinal VC-dimension offers a perfect characterization for the problem of predicting the truth of the members of D in a member of W, with an ordinal bound on the number of mistakes. This shows that the notion of VC-dimension has a natural interpretation in Inductive Inference, when cast into a logical setting. We also study the relationships between predictive complexity, selective complexity���a variation on predictive complexity���and mind change complexity. The assumptions that D is closed under boolean operators and that W is compact often play a crucial role to establish connections between these concepts. We then consider a computable setting with effective versions of the complexity measures, and show that the equivalence between ordinal VC-dimension and predictive complexity fails. More precisely, we prove that the effective ordinal VC-dimension of a paradigm can be defined when all other effective notions of complexity are undefined. On a better note, when W is compact, all effective notions of complexity are defined, though they are not related as in the noncomputable version of the framework.

Impediments to Cosmopolitan Engagement: Technology and Late-Modern Cosmopolitanism

What characterises late modern variety of cosmopolitanism from its classical predecessors is the inherent connection between cosmopolitanism and technology. Technology enables a vital dimension of the cosmopolitan experience ��� to move beyond the cosmopolitan imagination to enable active, direct engagement with other cultures. Different types of technologies contribute to cosmopolitan practice but in this paper we focus on a specific set of these enabling technologies: technologies which play a crucial role in regulating the free movement of people and populations. We briefly examine how three of the great surveillance states of the 20th century ��� Nazi Germany, the Soviet Union, and the German Democratic Republic ��� used hightech solutions in pursuing an anti-cosmopolitanism. We suggest that in the period from 2001 to the present, important elements of the cosmopolitan ethos are being closed down, and once again high-tech is intimately connected to this moment. The increasing (and proposed) use of identity cards, biometric identification systems, ITS and GIS all work to make the globalised world much harder to traverse and inhibit the full expression and experience of cosmopolitanism. The result of these trends may be that the type of cosmopolitan sentiment exhibited in western countries is an ersatz, emptied out variety with little political-ethical robustness.