The boron-oxygen (BO) defect is ubiquitously present in p-type Czochralski material and is known to cause significant carrier induced degradation in commercial solar cells. Despite being well-known for years, the nature and behaviour of the defect are not yet completely understood. This thesis aims to shed new insights into the properties of the BO defect and the mechanisms underlying known processes that can be used to mitigate its effects.This thesis begins with a review of the known properties and behaviours of the BO defect, and a summary of the key gaps in knowledge. Statistical regression-based methods to characterise the recombination properties of the defect at room temperature and at elevated temperatures using injection-dependent lifetime spectroscopy (IDLS) and temperature- and injection-dependent lifetime spectroscopy (TIDLS) are presented and applied to independently confirm the trap level (EC – (0.41 ± 0.01) eV), the associated capture cross section ratio (11.5 ± 1.0) and the power exponent of temperature dependence of the capture cross sections (-2.3 ± 0.1) associated with the BO donor level in p-type Czochralski wafers. Empirical models to determine effective carrier lifetime at elevated temperatures are also developed and applied to unambiguously determine the carrier dependence of the rate constants of degradation and annealing. These are then explicitly accounted for to obtain improved estimates of the associated activation energies and characteristic frequencies based on fits to datasets in this and other works in the literature.Also investigated in this thesis are various proposed mechanisms underlying permanent deactivation of the BO defect via rapid thermal annealing and via regeneration (illuminated annealing). It is concluded that the two effects occur independently and are likely unrelated. Thermal deactivation is explained as defect dissociation into precursors, whereas regeneration is concluded to be hydrogen passivation of the fully formed defect. Finally, the new insights gained into the nature of the BO defect and the configurational changes that occur during defect state transitions are discussed in the context of existing literature.
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