Fe gettering by p⁺ layer in bifacial Si solar cell fabrication

Gettering behaviors of Fe into solar cell grade Si are investigated by deep level transient spectroscopy. The samples contaminated with Fe in the range of the concentration of 1.5×10¹²-2.0×10 ¹⁴ cm^-3 were annealed at 600 °C to induce gettering. It is shown that the surface layer gettering behaviors of Fe for the sample without p⁺ layer strongly depend on the Fe contamination level, in which the surface layer gettering is not effective for the sample with low level contamination <1×10¹³ cm^-3 but effective for the sample with middle level contamination of 1-5×10¹³ cm^-3. In contrast, the samples with p⁺ layer show effective gettering for low and middle level contaminations. The gettering mechanisms in solar cell grade Si without and with p⁺ layer are discussed in details.