The fragmented and unequal system of technical and vocational education and training in South Africa is a consequence of the apartheid era. Since 1994 comprehensive legislation has been introduced to create a transformed system of Further Education and Training (FET) guided by the principles of redress, equity and lifelong learning and aimed at producing graduates who can contribute to making South Africa a key player in the global economy. In particular, the Technical College sector requires transformation. This in turn demands new knowledge, attitudes and skills from college managers and educators. Therefore, relevant staff development programmes is a key instrument of change in colleges. Against this background this study examines the management of staff development programmes in FET colleges in Gauteng Province by means of a literature study and an empirical investigation. The former addresses the management of change, human resource management, staff development and organisational development with an emphasis on the application of chaos/complexity theory. Moreover, the dynamic FET landscape in South Africa is sketched and FET policies and legislation since 1994 are discussed. The empirical investigation adopts a qualitative approach using focus group and individual interviews, observation and document analysis to gather data from a small sample of participants: educators and members of senior and middle management. Participants were selected by purposeful sampling from three former Technical Colleges (one previously advantaged and two previously disadvantaged) in Gauteng, which have recently merged to create a new multi-campus college, the Tshwane North College. The findings of the interviews present the experience of participants according to six themes: the management of change; communication during change; stakeholder involvement in change; the impact of FET legislation; human resource management and the role of staff development programmes in this process. These findings were integrated with observations of staff development programmes and their management and analysis of key documents. It was concluded that people are complex and may resist change; during change effective communication, stakeholder participation, adequate funding for staff development and its effective management are essential. Recommendations for the improvement of practice are presented based on the findings of the literature and empirical study. / Educational Studies / D. Ed. (Education Management)

The National Curriculum Statement (NCS) heralds the beginning of a new curriculum for Grades 10 to 12 in South Africa. Underpinned by the South African Constitution, and based on the tenets of Outcomes-based Education, the NCS seeks to provide contextually-relevant education for all South African learners, so that they are able to embrace inevitable change. Although the NCS highlights the importance of assessment, an analysis of the English Home Language (EHL) NCS reveals tensions between policy and practice. This study attempts to contextualise the role of relevant assessment for the 21st century. It then proceeds to engage in a historical evaluation of assessment within the NSC in terms of how assessment was conducted in the former Natal Education Department, a liberal education department within former apartheid South Africa. The conclusions drawn from the evaluation are used to provide recommendations to relieve the tensions identified within the EHL NSC. / Educational Studies / M.Ed.

Diploma thesis describes the design of an switched mode power supply with switching at zero voltage for driving the anode of Anode-layer type ion source. First aim of thesis is ion sources and specialy Anode-layer type of ion source in detail. Main aim of thesis are important aspects of the design of switching mode power supply, which comes later the detailed construction of an switched mode power supply with output voltage 2800 V at output power 2800 W.

Diese Arbeit beschäftigt sich mit der „First-Principles“ atomskaligen Modellierung der HfO2-basierten high-k-Gate-Isolatorschichten der Metalloxid-Halbleiter-Feldeffekttransistoren. Die theoretischen Untersuchungen basieren auf Dichtefunktionaltheorie und Nichtgleichgewicht-Greensche-Funktion-Formalismen. Eine der wichtigsten Eigenschaften eines Gate-Isolators ist der Wert seiner Bandlücke. Die Bandlücke eines gemischten Festkörpers aus SiO2 und ZrO2 oder HfO2 wird auf der Grundlage der „Generalized Quasi-Chemical“ Approximation in Kombination mit dem „Cluster Expansion“ Ansatz berechnet. Zu diesem Zweck wurde Dichtefunktionaltheorie für die Berechnung der Eigenschaften verschiedener Konfigurationen möglicher Elementarzellen durchgeführt. Es wurde ein fast linearer Verlauf für die Bandlücke eines aus SiO2 und HfO2 gemischten Festkörpers berechnet. Im Vergleich zu dem üblichen SiO2 Gate-Isolator, haben die high-k-Gate-Isolatoren eine höhere Defektdichte, die hauptsächlich aus Sauerstoffleerstellen bestehen. Dies führt zu mehreren Problemen, wie zum Beispiel höherer Leckstrom, Schwellenspannungsverschiebung und Degradation des Gateoxids. Daher wurde eine umfassende Untersuchung der verschiedenen Eigenschaften von Sauerstofffehlstellen in HfO2 durchgeführt, indem wichtige Parameter wie zum Beispiel die Formationsenergien und die Lage der Defektniveaus in der Bandlücke berechnet wurden. Es wurde durch die theoretischen Berechnungen gezeigt, dass die schädlichen Auswirkungen von Sauerstofffehlstellen durch die Einführung von Lanthan-Atomen in dem HfO2 Kristallgitter teilweise zu verringern sind. Energetisch gesehen bevorzugen die Lanthan-Atome die Hf-Gitterplätze in der Nachbarschaft einer Sauerstofffehlstelle und führen dadurch zu der Passivierung durch Sauerstoffleerstelle induzierten Defektniveaus. Die high-k-Isolatorschicht in den heutigen Transistoren besteht aus drei Schichten: einem Metallgate, einer HfO2-Schicht als Haupt-Gate-Isolator und einer sehr dünnen SiO2 Übergangsschicht zwischen Gateoxid und Si. Die Einführung eines Metallgates führt zu einigen Problemen bei der Einstellung einer geeigneten Schwellenspannung in den Transistoren. Theoretische Berechnungen in einer komplexen Modellstruktur von der Si/SiO2/HfO2-Grenzfläche zeigen, dass die dotierten Lanthan-Atome energetisch die SiO2/HfO2-Grenzfläche bevorzugen, was wiederum ein Dipolmoment an der Grenzfläche erzeugt. Dieses Dipolmoment kann verwendet werden, um die richtige Schwellenspannung wieder einzustellen. Schließlich wird in den experimentellen Messungen festgestelltes progressives Degradationsverhalten von high-k-Gate-Isolatoren mit einem theoretischen Modell erklärt. Dieses Modell basiert auf ab-initio-Berechnungen und zeigt, wie die Erzeugung geladener Sauerstoffleerstellen und deren Migration unter der angelegten Gatespannung zu einer progressiven Erhöhung des Leckstroms und folglich zu einer Degradation der Isolatorschicht führt.:List of Figures 7 List of Tables 9 List of Symbols 10 List of Abbreviations 11 Chapter 1: Introduction 12 Chapter 2: Theory of Atomic-Scale First-Principles Calculations 15 2.1 Theoretical methods 15 2.2 Density functional theory 17 2.3 Non-equilibrium Green’s function formalism 23 Chapter 3: Calculations for Bulk High-k Materials 27 3.1 Bulk high-k materials 27 3.2 Crystalline insulators 27 3.3 Solid solutions 29 3.3.1 Cluster expansion approach 30 3.3.2 Band gap and bowing parameter 33 3.3.3 Calculation of internal stress 40 3.4 Leakage current 41 Chapter 4: Defects in Bulk High-k Materials 43 4.1 Defects in high-k gate dielectrics 43 4.2 Oxygen vacancies in monoclinic HfO2 44 4.2.1 Neutral oxygen vacancies 44 4.2.2 Charged oxygen vacancies 46 4.3 Hybrid functional 50 4.4 Double oxygen vacancies 56 4.5 Interaction of oxygen vacancies with La-doping 61 4.5.1 La doping in m-HfO2 61 4.5.2 Complex LaHfVO defects 64 Chapter 5: Interface Properties of High-k Gate Stack 72 5.1 high-k gate-stack 72 5.1.1 Atomic-scale model structure for a high-k gate-stack 72 5.1.2 Electronic structure 74 5.1.3 Leakage current 76 5.2 Band offset 80 5.3 Threshold voltage engineering with La doping 84 Chapter 6: Degradation of the High-k Gate Stack 90 6.1 Reliability issues in high-k gate-stack 90 6.2 Calculations and experimental methods 91 6.3 Leakage current 92 6.4 Defect generation 100 6.5 Explaining progressive SILC in high-k dielectrics 102 Chapter 7: Conclusions 104 Bibliography 106 Selbständigkeitserklärung 119 Danksagung 120 Lebenslauf 121 Veröffentlichungen 122 / This thesis deals with the first-principles atomic-scale modeling of the HfO2-based high-k gate-insulator layer of the metal-oxide-semiconductor field-effect transistors. The theoretical investigations are based on density functional theory and non-equilibrium Green's function formalisms. One of the important properties of the gate insulator is the value of its band gap. The band gap of amorphous solid mixtures of SiO2 and ZrO2 or HfO2 is calculated based on generalized quasi-chemical approximation combined with a cluster expansion approach, by performing density functional calculations on different configurations of possible unit cells. An almost linear variation of the band gap is obtained for solid mixtures of SiO2 and HfO2. One drawback of the high-k gate-insulator, comparing to the standard SiO2, is high density of defects, particularly oxygen vacancies, which leads to several problems such as enhancement of the leakage current, threshold voltage instability, and degradation of the gate-oxide. A comprehensive investigation of different properties of oxygen vacancies in HfO2 is conducted by the calculation of formation energies and induced trap levels. It is shown based on theoretical calculations that the harmful effects of oxygen vacancies can be partially healed by introducing lanthanum atoms into the defected HfO2 crystal. Lanthanum atoms energetically prefer to occupy Hf lattice sites close to the oxygen vacancies and passivate the induced defect levels. The state-of-the-art high-k gate-stacks consist of a metal-gate on a HfO2 layer, as the main part of the gate insulator, and a very thin SiO2 intermediate layer between high-k material and Si. The introduction of a metal-gate raises some problem in the adjustment of an appropriate threshold voltage. Theoretical calculations in a complex model structure of the Si/SiO2/HfO2 interface reveals that the lanthanum atoms energetically prefer to stay at the SiO2/HfO2 interface, which in turn results in a dipole moment. This dipole moment can be employed to adjust the threshold voltage in high-k/metal-gate stacks. Finally, a theoretical model, which can quiet well explain the experimental measurements, is introduced for the progressive degradation of the high-k gate-insulators. This model is based on ab-initio calculations and shows how the generation of charged vacancies and their migration under the applied gate voltage leads to the progressive enhancement of the leakage current and consequently to the degradation of the insulator layer.:List of Figures 7 List of Tables 9 List of Symbols 10 List of Abbreviations 11 Chapter 1: Introduction 12 Chapter 2: Theory of Atomic-Scale First-Principles Calculations 15 2.1 Theoretical methods 15 2.2 Density functional theory 17 2.3 Non-equilibrium Green’s function formalism 23 Chapter 3: Calculations for Bulk High-k Materials 27 3.1 Bulk high-k materials 27 3.2 Crystalline insulators 27 3.3 Solid solutions 29 3.3.1 Cluster expansion approach 30 3.3.2 Band gap and bowing parameter 33 3.3.3 Calculation of internal stress 40 3.4 Leakage current 41 Chapter 4: Defects in Bulk High-k Materials 43 4.1 Defects in high-k gate dielectrics 43 4.2 Oxygen vacancies in monoclinic HfO2 44 4.2.1 Neutral oxygen vacancies 44 4.2.2 Charged oxygen vacancies 46 4.3 Hybrid functional 50 4.4 Double oxygen vacancies 56 4.5 Interaction of oxygen vacancies with La-doping 61 4.5.1 La doping in m-HfO2 61 4.5.2 Complex LaHfVO defects 64 Chapter 5: Interface Properties of High-k Gate Stack 72 5.1 high-k gate-stack 72 5.1.1 Atomic-scale model structure for a high-k gate-stack 72 5.1.2 Electronic structure 74 5.1.3 Leakage current 76 5.2 Band offset 80 5.3 Threshold voltage engineering with La doping 84 Chapter 6: Degradation of the High-k Gate Stack 90 6.1 Reliability issues in high-k gate-stack 90 6.2 Calculations and experimental methods 91 6.3 Leakage current 92 6.4 Defect generation 100 6.5 Explaining progressive SILC in high-k dielectrics 102 Chapter 7: Conclusions 104 Bibliography 106 Selbständigkeitserklärung 119 Danksagung 120 Lebenslauf 121 Veröffentlichungen 122

It is generally agreed that during the apartheid era secondary school History education was perceived as either an indispensible aid toward furthering the National Party’s social and political programme of separate development by some sections of the South African community or as an insidious form of indoctrination by other sections of the community. One of the contentions of this thesis is that this form of apology or indoctrination was less successful than is generally believed. The white English and Afrikaans-speaking sections of the community, although practising very different cultures shared many perceptions, including the perception that secondary school History education was less important than was the study of other subjects. The result was that at least since the 1960s, History was a subject in decline at most South African white secondary schools. History education enjoyed a mixed reception on the part of black secondary school educators during the apartheid era although the majority of black secondary school educators and learners, particularly after the 1976 Soweto Uprising, rejected the subject as a gross misrepresentation of historical record. The demise of History as a secondary school subject during the post-apartheid era is well documented. The case is made that this is due to factors such as poor teaching and the tendency by school administrations to marginalise the subject. My own 2008 and 2012 research indicates that while many South African adults display a negative attitude toward secondary school History education, secondary school learners have a far more positive outlook. The finding of this thesis is that the future for History education in South Africa is not as bleak as many imagine it appears to be. / History / D. Litt. et Phil. (History)

It is generally agreed that during the apartheid era secondary school History education was perceived as either an indispensible aid toward furthering the National Party’s social and political programme of separate development by some sections of the South African community or as an insidious form of indoctrination by other sections of the community. One of the contentions of this thesis is that this form of apology or indoctrination was less successful than is generally believed. The white English and Afrikaans-speaking sections of the community, although practising very different cultures shared many perceptions, including the perception that secondary school History education was less important than was the study of other subjects. The result was that at least since the 1960s, History was a subject in decline at most South African white secondary schools. History education enjoyed a mixed reception on the part of black secondary school educators during the apartheid era although the majority of black secondary school educators and learners, particularly after the 1976 Soweto Uprising, rejected the subject as a gross misrepresentation of historical record. The demise of History as a secondary school subject during the post-apartheid era is well documented. The case is made that this is due to factors such as poor teaching and the tendency by school administrations to marginalise the subject. My own 2008 and 2012 research indicates that while many South African adults display a negative attitude toward secondary school History education, secondary school learners have a far more positive outlook. The finding of this thesis is that the future for History education in South Africa is not as bleak as many imagine it appears to be. / History / D. Litt. et Phil. (History)

The aim of this study was to investigate the management of the function shift of Technical and Vocational Education and Training Colleges at the Department of Higher Education and Training. When the function shift of TVET Colleges took place, it provided an opportunity to research a phenomenon and obtain data that were not previously researched, as this was the first ever function shift or migration of colleges from the Department of Basic Education to the Department of Higher Education and Training. As such, this research not only explores a new phenomenon but also contributes to the body of knowledge regarding TVET in South Africa. This research was conducted at a TVET College in Newcastle, Kwa-Zulu Natal, South Africa. A qualitative, phenomenological study was conducted. The instruments for collecting data were individual and focus group interviews. Field notes were compiled during the various interviews, as deemed necessary by the researcher. All interviews were recorded digitally. The said digital recordings were transcribed and emanating themes were identified. Managers were selected as the interviewees. As this research was based on the management of the function shift, they were the most appropriate choice. A sample of staff was also interviewed, as two separate focus groups, to balance the scope and extent of the data, thus attempting to not only view the managerial paradigm as the sole reality. Findings made from the data were that the function shift was preceded by a previous migration of staff. That migration, however, saw colleges remaining in the same educational stream or level namely that of basic education. The staff at colleges, or technical colleges as they were called at the time, were previously employed by the State. This changed when the State created governing bodies for colleges or college councils, as they are known. Technical Colleges were then renamed Further Education and Training Colleges. These colleges were reporting to the Department of Education which saw a name change to the Department of Basic Education, as explained above. Employees were given the opportunity to migrate from State employment to council employment, which most staff members did. These college councils were later found to be dysfunctional, and the State arranged for colleges to be returned to the auspices of the State, but this time round they were usurped in the newly formed Department of Higher Education and Training. From a management perspective, the function shift was successful with minor challenges. Thus the staff felt that they did not receive adequate communication, thereby adversely affecting their financial positions. The researcher recommends further research among TVET Colleges regarding the management of this function shift. It is also recommended that all current channels of communication with staff be revisited, and improvement therein pursued, where possible. A final recommendation is that managers involved in a function shift be subject to a refresher course in change management before a function shift is implemented. / Educational Leadership and Management / M. Ed. (Education Management)

Extracellular neuroelectronic interfacing has important applications in the fields of neural prosthetics, biological computation and whole-cell biosensing for drug screening and toxin detection. While the field of neuroelectronic interfacing holds great promise, the recording of high-fidelity signals from extracellular devices has long suffered from the problem of low signal-to-noise ratios and changes in signal shapes due to the presence of highly dispersive dielectric medium in the neuron-microelectrode cleft. This has made it difficult to correlate the extracellularly recorded signals with the intracellular signals recorded using conventional patch-clamp electrophysiology. For bringing about an improvement in the signalto-noise ratio of the signals recorded on the extracellular microelectrodes and to explore strategies for engineering the neuron-electrode interface there exists a need to model, simulate and characterize the cell-sensor interface to better understand the mechanism of signal transduction across the interface. Efforts to date for modeling the neuron-electrode interface have primarily focused on the use of point or area contact linear equivalent circuit models for a description of the interface with an assumption of passive linearity for the dynamics of the interfacial medium in the cell-electrode cleft. In this dissertation, results are presented from a nonlinear dynamic characterization of the neuroelectronic junction based on Volterra-Wiener modeling which showed that the process of signal transduction at the interface may have nonlinear contributions from the interfacial medium. An optimization based study of linear equivalent circuit models for representing signals recorded at the neuron-electrode interface subsequently iv proved conclusively that the process of signal transduction across the interface is indeed nonlinear. Following this a theoretical framework for the extraction of the complex nonlinear material parameters of the interfacial medium like the dielectric permittivity, conductivity and diffusivity tensors based on dynamic nonlinear Volterra-Wiener modeling was developed. Within this framework, the use of Gaussian bandlimited white noise for nonlinear impedance spectroscopy was shown to offer considerable advantages over the use of sinusoidal inputs for nonlinear harmonic analysis currently employed in impedance characterization of nonlinear electrochemical systems. Signal transduction at the neuron-microelectrode interface is mediated by the interfacial medium confined to a thin cleft with thickness on the scale of 20-110 nm giving rise to Knudsen numbers (ratio of mean free path to characteristic system length) in the range of 0.015 and 0.003 for ionic electrodiffusion. At these Knudsen numbers, the continuum assumptions made in the use of Poisson-Nernst-Planck system of equations for modeling ionic electrodiffusion are not valid. Therefore, a lattice Boltzmann method (LBM) based multiphysics solver suitable for modeling ionic electrodiffusion at the mesoscale neuron-microelectrode interface was developed. Additionally, a molecular speed dependent relaxation time was proposed for use in the lattice Boltzmann equation. Such a relaxation time holds promise for enhancing the numerical stability of lattice Boltzmann algorithms as it helped recover a physically correct description of microscopic phenomena related to particle collisions governed by their local density on the lattice. Next, using this multiphysics solver simulations were carried out for the charge relaxation dynamics of an electrolytic nanocapacitor with the intention of ultimately employing it for a simulation of the capacitive coupling between the neuron and the v planar microelectrode on a microelectrode array (MEA). Simulations of the charge relaxation dynamics for a step potential applied at t = 0 to the capacitor electrodes were carried out for varying conditions of electric double layer (EDL) overlap, solvent viscosity, electrode spacing and ratio of cation to anion diffusivity. For a large EDL overlap, an anomalous plasma-like collective behavior of oscillating ions at a frequency much lower than the plasma frequency of the electrolyte was observed and as such it appears to be purely an effect of nanoscale confinement. Results from these simulations are then discussed in the context of the dynamics of the interfacial medium in the neuron-microelectrode cleft. In conclusion, a synergistic approach to engineering the neuron-microelectrode interface is outlined through a use of the nonlinear dynamic modeling, simulation and characterization tools developed as part of this dissertation research.