Polarization dependent light extinction in ensembles of polydisperse, vertical semiconductor nanowires : a Mie scattering effective medium

We present an experimental and theoretical study of the angle- and polarization-dependent light extinction in random arrays of polydisperse semiconductor nanowires epitaxially grown on substrates. The specular reflectance is described by averaging the scattering properties of individual nanowires obtained from Mie theory over the diameter distribution. The complex effective refractive index describing the propagation and attenuation of the coherent beam scattered in a forward direction is determined in the independent scattering approximation and used to calculate the angle- and polarization-dependent reflectance. Our measurements demonstrate the highly anisotropic scattering in ensembles of aligned nanowires.