Oxidative-gravimetric porosimetry of macroporous silicon

A simple nondestructive method to find the internal surface area, porosity, pore diameter, and pore density in macroporous silicon with through channels is suggested and tested. The porosity p is determined from the mass loss upon anodizing, and the surface area per unit volume, S, from the mass Of SiO2 formed on the pore surface upon thermal oxidation. The relations are given for calculation of the average pore diameter d and pore density N from the obtained S-V and p. Dependences of the specific surface area and porosity on the resistivity of initial n-Si in the range rho = 3-25 Omega cm have been studied for samples with ordered and self-organized "lattices" of macropores. The obtained values are within the limits p = 27-50%, S-V = 2800-6000 cm(2)/cm(3), d = 1.9-6.5 mu m, and N = 1.4-10 x 106 cm(-2), in acyreement with the data furnished by microscopy.