Gravimetric method to find internal surface of macroporous silicon membranes

Abstract

AbstractA simple method to evaluate the internal surface area, porosity, pore diameter and pore density of macroporous silicon membranes has been proposed and tested. The porosity p is obtained from the mass loss under anodizing, and the surface area per unit volume Sv is determined from the mass of SiO2 formed on the pore surface as a result of thermal oxidation. The average pore diameter d and pore density N can be easily calculated from the obtained Sv and p. Experimental verification of d and N was performed by means of SEM and optical microscope images; Sv was checked by BET technique. Surface area and porosity on the resistivity of initial n‐Si in the range ρ = 3–25 Ohm · cm have been studied for the samples with regular and self‐organized macropore “lattices”. The obtained values are within the limits p = 27–50%, Sv = 2800–6000 cm2/cm3, d = 1.9–6.5 μm, N = 1.4–10 × 106 cm–2, and in a good agreement with the data of microscopic characterization. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)