Ellipsometric studies on rough Zn and Cd polycrystalline samples

A manual null ellipsometer is constructed and used to determine the optical constants of zinc and cadmium of different surface roughness at the wavelength 632.8 nm, angle of incidence 45° and room temperature. The studied samples are polycrystalline sheets of thickness ~ 0.05 mm and surface area 30 mm x 30 mm. The samples were mechanically polished using diamond paste of different grain sizes. The final stage of polishing for the samples was with pastes of grain size 0.5 μm, 2.5 μm, 5 μm, 10 μm and 14 μm. The ellipsometric parameters ψ and Δ were obtained and were used to calculate the optical constants n (refractive index) and k (extinction coefficient). It was found that as the roughness is increased, the refractive index n increases while the extinction coefficient k decreases. The used optical arrangement for ellipsometric measurements is presented and the procedure for extracting the results is explained. The uncertainty in the results is calculated and included in the results.