Iron Silicide Formation by Precipitation in a Silicon Bicrystal

Metal Impurity Redistribution in Crystalline Silicon for Photovoltaic Application

“…The driving force results from a lower chemical potential in regions with higher solubility. Precipitation seems to be the dominating effect for impurity accumulation because there is only little experimental evidence for segregation as mechanism of impurity accumulation at grain boundaries [16,69], while there is solid evidence for precipitation at grain boundaries as shown in this work (please see section 3, Falkenberg et al [43] and Falkenberg and Seibt [71] and by several other authors [72,73,74]. Consistently, simulations in this work also indicate that segregation has only minor effect and experimental results can well be modeled by using a model with only precipitation as mechanism of impurity accumulation (please see section 5.5.…”

Impurity Precipitation, Dissolution, Gettering and Passivation in PV Silicon: Final Technical Report, 30 January 1998--29 August 2001

“…However, the formation of distinctive large iron-silicide precipitates at extended defects is very uncommon. With a few exceptions (such as [140]), it was found that iron precipitates along dislocation lines very uniformly, and does not form any contrast spots in EBIC images, common for Cu-contaminated samples [84,117].…”

Gettering Processes and the Role of Extended Defects

“…Systematic studies mainly on bicrystals containing well-defined grain boundaries have been performed for nickel, copper, and iron showing that silicide precipitates form in the grain boundary plane (see, e.g., for Cu: [135,[220][221][222], Ni: [223][224][225][226], Fe: [227,228]) that in general leads to rather strong excess carrier recombination. Ihlal and Rizk [228] compare grain boundaries in iron-contaminated bicrystals for different cooling rates terminating the iron in diffusion.…”