Browsing by Author "Walton, Stanley Douglas"

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    The development of a cost-effective beam loss monitor for use at the K600 magnetic spectrometer at iThemba LABS
    (2008) Walton, Stanley Douglas; Fearick, Roger
    The purpose of this work was to develop a cost-effective beam loss monitor for use at the K600 magnetic spectrometer at iThemba LABS. To this end. the commonly used materials and technologies were reviewed and photo diodes were chosen because of their low price, high performance and ready availability. Experiments have been carried out and compared to theoretical calculations. Recommendations for future developments are presented.
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    Fully printed transistors employing silicon nanoparticles
    (2014) Walton, Stanley Douglas; Britton, David T; Härting, Margit
    A new device, which utilises a previously unknown two-way mode of current switching, has been developed. This is the current switching transistor, a three-terminal electronic device which exhibits a transfer resistance, in which the application of a potential or injection of charge to one terminal controls the current at either of the two remaining terminals. The development of the current switching transistor arose from a more general project focussed on printed electronics using nanoparticulate silicon, with the aim of producing fully printed transistors. All of the printed transistors produced to date have been field-effect transistors (FETs), due to the fact that printing processes are easily applicable to the planar FET architectures. The majority of the work in the area of printed FETs has so far been focussed on the use of organic semiconducting polymers to produce organic field-effect transistors (OFETs). However, research has also been undertaken regarding the use of inorganic semiconductors, including for example, transparent metal oxides, compound semiconductors and silicon. Of the active devices, the key element is the transistor. It is essential, especially for its function as an electronic switch, in enabling a wide variety of technologies. Of particular interest are its applications in digital electronics, including logic gates, memory and comparators. The ultimate goal of printed electronics is to replace conventional electronic components with their printed equivalents, which requires the use of functional inks to deliver the desired electronic properties. Printed electronic components have potential advantages over conventional discrete and integrated circuits, especially in applications in which the printed electronics form factor is more important than the absolute technical performance of the system. Furthermore, the processes of fabrication of printed devices are far simpler and more cost efficient than those of conventional devices. This is particularly true for the current switching transistor, which can be realised by a simple two layer print.