Preparation of Large-Area Porous Silicon through Cu-Assisted Chemical Etching

Porous silicon (PS) was prepared with catalyst of Cu nanoparticles in HF/H2O2 solutions. The effects of the key fabrication parameters (amount of copper, etching temperature and concentration of H2O2) on the nanostructure of PS were systematically investigated and discussed. The experimental results indicated that the porosity of PS increased with the amount of copper, the reaction temperature and the concentration of H2O2, respectively. Copper can be used as catalyst to assist in etching silicon and the evolution process of copper nanoparticles was explored showing that the mass of copper experienced a drastic reduction in the first 60 seconds. A mechanism is proposed to explain the formation of PS by Cu-assisted chemical etching.