by Lo Veng Cheong. / Parallel title in Chinese characters. / Thesis (Ph.D.) -- Chinese University of Hong Kong, 1991. / Bibliography: leaves 116-119. / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / LIST OF SYMBOLS --- p.iv / LIST OF FIGURES --- p.ix / LIST OF TABLES --- p.xii / Chapter CHAPTER ONE --- INTRODUCTION --- p.1 / Chapter CHAPTER TWO --- SURVEYS ON THEORETICAL MODELS --- p.7 / Chapter 2.1 --- Some Basic Concepts --- p.7 / Chapter 2.1.1 --- Vacancy Mechanism and Interstitial Mechanism --- p.7 / Chapter 2.1.2 --- Relative Contribution from Various Point Defects Species --- p.15 / Chapter 2.1.3 --- Impurity Point Defect Pairs or 'Centers' --- p.20 / Chapter 2.1.4 --- Anomalous Diffusion --- p.21 / Chapter 2.2 --- Historical Review on Theoretical Models --- p.22 / Chapter 2.3 --- Formulation of the General Model --- p.29 / Chapter 2.3.1 --- Effects to be and Not to be Considered --- p.30 / Chapter 2.3.2 --- Derivation of the Basic Equations --- p.31 / Chapter CHAPTER THREE --- MODELING OF THE DAMAGE ENHANCED DIFFUSION OF IMPLANTED BORONS IN SILICON --- p.35 / Chapter 3.1 --- Brief Description of Powell's Experiment --- p.35 / Chapter 3.2 --- Modeling --- p.38 / Chapter 3.3 --- Results and Discussion --- p.45 / Chapter CHAPTER FOUR --- EXPERIMENTAL INVESTIGATION OF BORON DIFFUSION DIFFUSION ASSISTED BY THE NON-UNIFORMITY OF POINT DEFECTS --- p.66 / Chapter 4.1 --- Introduction --- p.66 / Chapter 4.2 --- Experimental --- p.67 / Chapter 4.3 --- Results and Discussion --- p.88 / Chapter CHAPTER FIVE --- CONCLUSION AND FURTHER SUGGESTIONS --- p.103 / Chapter 5.1 --- Conclusion --- p.103 / Chapter 5.2 --- Further Suggestions --- p.104 / Chapter APPENDIX A --- DOPANT CONCENTRATION DEPENDENCE OF THE ENHANCED DIFFUSION --- p.107 / Chapter APPENDIX B --- FLOW CHART OF NUMERICAL SIMULATION --- p.111 / REFERENCE --- p.116

Please read the abstract in the section 00front of this document / Thesis (PhD (Physics))--University of Pretoria, 2006. / Physics / unrestricted

M.Sc. / Techniques for the fabrication of polycrystalline silicon solar cells have advanced in recent years with efficiencies exceeding 17%. The major advantage of polycrystalline silicon is its low cost relative to single-crystalline silicon. The disadvantage is the significantly smaller minoritycarrier bulk diffusion length and inhomogeneous nature of the material. These two drawbacks are due to the presence of grain boundaries as well as high concentrations of dislocations and other physical and chemical defects. In this study the experimental conditions were determined to fabricate solar cells on polycrystalline silicon substrates. The controlled diffusion of phosphorous into silicon and subsequent evaluation of the doped layers (by spreading resistance profiling and chemical staining) were important aspects of this study. From these results the diffusion parameters (i.e. temperature and reaction times) could be optimized in order to improve the solar cell output parameters. Additional material improvement (increase in surface- and bulk minority carrier lifetimes) was demonstrated by the hydrogen passivation of electrically active defects in polycrystalline silicon. However. measurements on hydrogenated silicon samples also indicated that excess passivation can result in surface damage and subsequent reduction in the minority carrier lifetimes. Preliminary solar cells were fabricated on polycrystalline silicon with efficiencies ranging between 0.5 and 6% (total area = 16 cm2).