Abstract
        We calculate the dielectric constants and absorption coefficient of porous silicon from the reflectance. The normal 
reflectance was measured at 200-3000 nm range by unpolarized light. Kramers-Kronig analysis has been taken to use 
reflectance data. The real part of dielectric constant, ε1, decreases with increasing porosity in visible region. However, 
absorption coefficient, α, increases with increasing porosity in visible region. Also the void fractions were determined from 
effective media approximation (EMA). Our results show that maximum void fractions are in visible region and it increases 
with increasing porosity. A good agreement is found between EMA and Kramers-Kronig results.
        Keywords
        Porous silicon, Dielectric constants, Kramers-Kronig method, Effective media approximation (EMA), Absorption coefficient.
        Citation
        S. RAMEZANI SANI, A. MORTEZAALI, R. S. DARIANI, M. R. SARKARDEI, Nanostructure effect on optical properties of porous  silicon, Optoelectronics and Advanced Materials - Rapid Communications, 2, 7, July 2008, pp.424-427 (2008).
        Submitted at: April 26, 2008
 
        Accepted at: July 8, 2008