SECOND-ORDER SCATTERING INDUCED REFLECTION DIVERGENCE AND NONLINEAR DEPOLARIZATION ON RANDOMLY CORRUGATED SEMICONDUCTOR NANO-PILLARS

Second-order scattering induced re∞ection divergence and nonlinear depolarization on randomly sub-wavelength corrugated semiconductor nano-pillar surface is observed, which explains the nonlinear transverse electric (TE)/transverse magnetic (TM) mode transformation of the nano-pillar surface re∞ection with diminishing Brewster angle. The re∞ected fleld polarization ratios are increased from 0.12 to 0.65 and from 0.11 to 0.55 under TE- and TM- mode incidences by increasing Si nano-pillar height from 30 to 240nm. A small-perturbation modeling corroborates the scattering induced second-order polarization transformation to depolarize the re∞ection from highly corrugated Si nano-pillar surface. The higher fleld polarization ratio at TE-mode re∞ection caused by a severer inhomogeneous Si nano-pillars oriented in parallel with surface normal is concluded. With the enlarged fleld polarization ratio under TM- mode incidence, the angular dependent re∞ectance spectra with a gradually diminished and shifted Brewster angle from 74 - to 45 - can be simulated. The nano-roughened surface induced second-order scattering model correlates the diminishing Brewster angle with the surface depolarized re∞ection.