Surface modifications by wet oxidation method removing getter layer in crystalline silicon cells

Reducing the impurity atom content in crystalline silicon (c-Si) can effectively reduce the recombination current density (J(0)) and improve the photoelectric conversion efficiency (PCE) of solar cells. Phosphorus diffusion gettering (PDG) has been proven to be an effective method to remove impurity atoms from c-Si. However, the research studies show that the traditional tube thermal diffusion method will cause a large number of dislocations on the silicon surface during the oxidation process, reducing the effectiveness of gettering. In this paper, the wet oxidation method is systematically used to remove phosphorus-rich layers (PRL) and modify the surface. The gettering effectiveness is measured by the minority carrier lifetime (τ(eff)) and bulk carrier lifetime (τ(bulk)) of silicon wafers. The results show that wet oxidation can reduce J(0) by 27.0% and increase τ(eff) by 26.3%. For the bulk region, the average τ(bulk) can be increased by more than 6–14%. In addition, with the final PCE comparison, the efficiency of the wet oxidation cell will be improved by 0.12%. These works indicate that the wet oxidation method can significantly improve the gettering effectiveness and the PCE of c-Si solar cell fabrication.