published_or_final_version / Physics / Doctoral / Doctor of Philosophy

The classical capacitance voltage characteristics based on the depletion approximation, is adequate at reverse bias, but introduces errors at high forward bias. Because of its inherent simplicity and compactness this classical depletion model is well studied and widely used in circuit simulators. In this work, a new model for the semiconductor space charge region (SCR) capacitance, based on physical justification, will be derived. This new model takes three input parameters, C0 , Vbi and m, thus eliminating the fitting parameter FC currently used in SPICE. This new model is applicable for any applied voltage and will be compared with the SCR capacitance extracted from the numerical device simulator PISCES, and with the SCR capacitance models proposed by Gummel and Poon and by DeGraaff and Klaassen.

Magister Educationis - MEd / This study investigated 1) the conceptions on capacitors held by a group teachers in the Western Cape; 2) the effect of a dialogical argumentation instructional model on the teachers’ conceptions on the capacitor; and 3) the teachers’ perceptions on the implementation of this instructional model. The theoretical framework of the study was based on Toulmin’s Argumentation Pattern (TAP) and Ogunniyi’s Contiguity Argumentation Theory (CAT). The objective was to retrain science teachers in their awareness and understanding of the Nature of Science and Indigenous Knowledge Systems thereby enhancing their ability and efficacy in integrating science and Indigenous Knowledge Systems. The study involved workshop activities that included the teachers’ Reflective Diary, interview sessions, and video-taped lesson observations. The study adopted a Case Study approach and the data was analysed both quantitatively and qualitatively. The findings of the study showed that: 1) the teachers held varying conceptions of the capacitor; 2) the teachers’ conceptions of the capacitor improved after being exposed to the Dialogical Argumentation Instructional Model and 3) the teachers were dominantly in favour of the Dialogical Argumentation Instruction Model as a teaching method to be introduced at schools. The implications of the findings for school science and pedagogy were highlighted for closer observation.