Optimization of Si photocathode formation conditions through correlation between saw damage removal and black Si

Abstract

This study aimed to address the correlation between the saw damage removal (SDR) process and the formation of a nanoporous structure in order to fabricate a phototoelectrochemical (PEC) water splitting photocathode using silicon (Si) wafer utilized in solar cell. The experimental conditions were categorized into two groups: 1) before and after SDR process, and 2) the nanoporous structure formation time (ranging from 1 to 10 min) to identify the optimized conditions for enhancing efficiency. The results showed that the Si photocathode manufactured with a nanoporous structure fabricated for 5 min after SDR process had the lowest reflectance and interfacial defect, and the highest photocurrent density. This is because saw damage on the wafer caused many defects on the surface, making it difficult to form a uniform nano-porous structure. The SDR process helped in eliminating the saw damage and creating a uniform Si surface. In addition, the uniform nanoporous structure facilitated substantial light absorption, leading to the creation of numerous electrons and hole pairs, and resulted in achieved high efficiency by providing smoother the movement of carriers due to low interfacial defects. In summary, this study established a correlation between the SDR process and the formation of a nanoporous structure in the manufacturing of Si wafer for solar cells as a photocathode, and confirmed that the uniform nanostructure remarkably improves the photocurrent density characteristics.