Determination of pore size distribution and surface area of thin porous silicon layers by spectroscopic ellipsometry

A non-destructive method for investigation of pore size distribution and su rface area of porous silicon is presented. Adsorption and desorption isothe rms of water in thin films of porous silicon an analyzed using variable ang le of incidence spectroscopic ellipsometry. The analysis is based on multil ayer optical models and the Bruggeman effective medium approximation. Pore size distribution and surface area are extracted from the isotherms employi ng the Wheeler theory combined with the Kelvin and Cohan equations. Good ag reement is obtained between the calculated pore size distribution and estim ations made by scanning electron microscopy. The evaluated specific surface area for the porous layers presented here is: similar to 180 m(2)/cm(3), w hich is in good agreement with the value reported in the literature. (C) 20 01 Elsevier Science B.V. All rights reserved.