Abstract
Porous silicon (PS) made from highly doped material is modeled as a uniaxial effective medium consisting of two components: hollow cylindrical silicon shells and free cylindrical pores. The complex refractive index is calculated in the coherent potential approximation leading to a very good agreement with the experimental refractive index data. Light scattering in porous silicon is estimated using the vector radiative transfer theory. It is found that the diffuse reflectance of a porous layer at its interface with air agrees with the available experimental measurements of light scattering from p+ porous silicon at a wavelength λ=457 nm. It is also found that, at longer wavelengths, the diffuse reflectance can be much higher, and increases with the porous layer thickness, reaching a maximum value of almost 10% for very thick layers. As for the scattered light transmitted or reflected through a PS/Si interface, a qualitative agreement is obtained between the model and the available measurements of the spectral photoconductivity of a silicon wafer with a front-surface porous film and the optical transmittance of a silicon wafer with a back-surface porous film.
Published Version
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