Validity Analysis of Effective Medium Theory and Long Wave Approximation for the Optical Properties of Metal Surface Layer with Surface Roughness.

Abstract

The effects of surface roughness on the optical properties of metals have been discussed by comparing experimental results of ellipsometry with theoretical results from the homogeneous effective medium model (HEM), the monolayer effective medium model (MEM) and the gradual density layer model (GDL). A gradual increase of |rp/rs|(=p) has been observed with the increase in surface roughness at a higher angle than θB and gradual decrease at lower angle than θB, where θB is the pseudo-Brewster's angle. Though HEM models do not explain the roughness effect on optical properties, MEM model and GDL model show good explanations for the optical effects from rough metal surface, when Δd<<λ.