Calculation model of rough gold optical constants

Optical constants of electrodeposited thick gold (1 μm) films on nickel with root mean square (RMS) roughness between 5 and 100 nm are calculated using both the Azzam–Bashara multiple-reflection-transmission model and the Maxwell–Garnett law. The solid fraction variation in the roughened surface layer can be calculated with a Gaussian function depending on RMS, measured by atomic force microscope. Calculated and experimental ellipsometric parameters ψ and Δ are in good accordance and the optical constants varies with RMS in accordance with the theory.