Improvement of annealing procedure to suppress defect generation during impurity gettering in multicrystalline silicon for solar cells

We demonstrate an improved annealing procedure to suppress defect generation during impurity gettering process. A multiple cycled annealing and cooling for impurity gettering provides higher carrier lifetime in the wafers compared with continuously annealed wafers (conventional method). Microscopic photoluminescence images revealed that dislocation propagation from grown-in dislocations and defect generation in intra grain were suppressed in samples with the multiple cycled annealing. Therefore the multiple cycled annealing procedure is concluded to be a promising technique to improve electrical property of multicrystalline silicon for solar cells.