Role of heavily b-doped layer on low-temperature Fe gettering in bifacial Si solar cell fabrication

The gettering behaviors of Fe into Si with and without a p⁺ layer are investigated by deep-level transient spectroscopy. The samples contaminated with Fe in a wide concentration range were annealed at 600°C to induce gettering. The surface-layer gettering behaviors of Fe for the sample without the 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 at a concentration of less than 1 × 10 ¹³cm^-3 but effective for the sample with middle-level contamination at a concentration of (1-5) × 10¹³cm ^-3. In contrast, the samples with the p⁺ layer show effective gettering for low- and middle-level contaminations. The gettering mechanisms of Fe in Si without and with the p⁺ layer are discussed in detail.