Determination of a grown oxide layer thickness and optical constants of Zn and Cd metals

Abstract

Optical constants of Zn and Cd polycrystalline metals are measured using both quasi polarizing angle and principal angle of incidence methods at wavelength 633 nm. The quasi polarizing angle is the angle at which the intensity of the p-polarized reflection component reaches its minimum value. It depends only on the rotation of the sample using a rotating stage (with accuracy ± 0.1º) without moving any other parts in the optical setup. This method is considered the most accurate method for determining the optical constants of metal. These two methods are performed to investigate the difference between the quasi polarizing angle and the principal angle of incidence and to determine the optical constants of Zn and Cd metals. To verify the optical constants results of both methods, the same metals are measured by manual null ellipsometer. Very strong correlation is found between all results of optical constants. The thickness of a grown oxide layer, which is naturally formed on the surface of a metal, is measured using PHE-103 spectroscopic ellipsometer. A polishing process is performed to each metal before measuring the thickness of the grown oxide layer with time. It is found that the formed layers grow up faster after polishing and the rate of growth decreases with time. In a period of 144 h, the oxide layer formed on zinc is about three times that formed on cadmium.