Effect of Contamination Level and Gettering Parameters on Solar Cell Performance in Iron Contaminated Silicon

Czochralski-silicon wafers with different initial iron contamination levels were processed to solar cells using systematically varying phosphorus diffusion gettering (PDG) parameters. The cells were characterized by injection level dependent effective lifetime (eff) and two-diode model parameter analysis. A strong dependency between the effective lifetime (eff) and the gettering efficiency was demonstrated. The huge potential of PDG was most prominently seen in initially highly iron contaminated cells: eff value of the cells with initial bulk iron concentrations as high as 2×1014 cm-3 was recovered to the same level as the non-contaminated cells. Two-diode model analysis showed a strong correlation between the gettering efficiency and the diffusion current density (Jdiff), while the behavior of the recombination current density (Jrec) was not observed to be as straightforward.