Controlling impurity distributions in crystalline Si for solar cells by using artificial designed defects

We report on the controlling of iron impurity distributions in Si by using artificial designed defects. We utilized Si wafers, which were designed to have high density of localized dislocations and high-quality region, for measurement of the interstitial iron concentration and total iron amount. It is suggested that interstitial irons can be accumulated at high density of dislocations by annealing at 600°C. In addition, interstitial iron concentrations were decreased by slow cooling from 800°C to 400°C. These results show that a large number of interstitial irons are precipitated at high density of dislocations by annealing. Therefore, it is considered that impurity distribution can be controlled by using artificial designed defects under certain annealing condition. •We proposed the annealing condition for impurity trapping at defects area in c-Si.•Impurity distribution could be controlled by using artificial designed defects.•The Fei was accumulated at dislocations when annealed at 600°C .•When cooling linearly, many Fei were precipitated at high dislocation density area.