Self-purification model for metal-assisted chemical etching of metallurgical silicon

Electrochimica Acta 138 476-480

https://doi.org/10.1016/j.electacta.2014.05.048

Xiaopeng Li, Yanjun Xiao, Chenglin Yan, Keya Zhou, Paul-Tiberiu Miclea, Sylke Meyer, Stefan L. Schweizer, Alexander Sprafke, Jung-Ho Lee, Ralf B. Wehrspohn

Abstract

Metal-assisted chemical etching (MaCE) of metallurgical-grade silicon (MG-Si) has improved the purity of MG-Si (∼99%) to close to solar-grade (∼99.9999%) by removing metal impurities during the successful preparation of porous silicon nanowires (SiNWs). A new etching principle is proposed to explain the different levels of chemical reduction between various metal impurities with pore formation during etching. This model provides chemical insights into the relationship between dissolved metal ions and pores evolved during the formation of SiNWs.