Optimization Study on Preparation of Macroporous Silicon on P-Type Silicon Substrate by Electrochemical Etching

Low cost electrochemical etching method was utilized to prepare macroporous silicon on p-type silicon substrate in dilute HF solution. By optimizing the substrate resistivity, the etching current density, and the etching time, excellent macroporous silicon was obtained on 15 Ω•cm p-type silicon substrate with the pore diameter of about 2 μm, the pore depth of about 30 μm, and the surface pore density up to ~107/cm2. Such macroporous silicon gave out an excellent antireflective performance with the reflectance lower than 4% in a wide spectral range of 400-1000 nm. The low reflectance combined with the deep pore morphology provides an attractive potential to fabricate radial p-n junction solar cells on such macroporous silicon.