Impact of interstitial iron on the study of meta-stable B-O defects in Czochralski silicon: Further evidence of a single defect

Abstract

We explore the influence of interstitial iron (Fei) on lifetime spectroscopy of boron-oxygen (B-O) related degradation in p-type Czochralski silicon. Theoretical and experimental evidence presented in this study indicate that iron-boron pair (Fe-B) related reactions could have influenced several key experimental results used to derive theories on the fundamental properties of the B-O defect. Firstly, the presence of Fei can account for higher apparent capture cross-section ratios (k) of approximately 100 observed in previous studies during early stages of B-O related degradation. Secondly, the association of Fe-B pairs can explain the initial stage of a two-stage recovery of carrier lifetime with dark annealing after partial degradation. Thirdly, Fei can result in high apparent k values after the permanent deactivation of B-O defects. Subsequently, we show that a single k value can describe the recombination properties associated with B-O defects throughout degradation, that the recovery during dark annealing occurs with a single-stage, and both the fast- and slow-stage B-O related degradation can be permanently deactivated during illuminated annealing. Accounting for the recombination activity of Fei provides further evidence that the B-O defect is a single defect, rather than two separate defects normally attributed to fast-forming recombination centers and slow-forming recombination centers. Implications of this finding for the nature of the B-O defect are also discussed.

Defect concentration and Δn change in light- and elevated temperature-induced degradation

“…For instance, using ∆n = 0.1 × N dop may not always be suitable, such as in the presence of iron. This can be overcome when ∆n is extracted at the cross-over point [26], which has been demonstrated in our previous study [27], but then the ratio of ∆n and N dop may no longer be the same with different N dop values.…”

“…Our previous study showed that depending on the period where one of the two types of LID dominates, the k of each type can be carefully calculated to eliminate or minimise the influence of each other. Moreover, the presence of multiple types of LID can lead to change in the apparent value of k over time [27], which can, therefore, be considered or potentially isolated. Any fitting approach like Murphy et al [36] that uses residual of the measurement with and without the presence of a defect can potentially have this problem.…”

Features of the Formation of the BiBs Defect in Si

“…The properties of B i O i defects were studied in many works. The B i O i defect has been of significant interest to the photovoltaic community because the light‐induced degradation of solar cells is associated with the boron–oxygen‐related defect . The available information about properties of the B i C s , B i B s , and B i B i complexes is yet insufficient.…”

Transition Metals in a Cast‐Monocrystalline Silicon Ingot Studied by Silicon Nitride Gettering

“…They reduce the carrier lifetime of silicon materials in both the dissolved state and the precipitated state, and are thus detrimental to silicon solar cells . Knowledge of the metal concentrations in silicon materials is also significant for the studies of other defects, including light and elevated temperature‐induced degradation, decorated crystal defects such as dislocations and grain boundaries, copper‐related light‐induced degradation, boron‐oxygen‐related defects, ring defects, and so on. The metal concentrations in multicrystalline silicon (mc‐Si) ingots have been successfully determined by applying neutron activation analysis in previous studies .…”