Optical Constants by Ellipsometry

Abstract

<p> The standard technique of ellipsometry allows the determination of the optical constants of a substrate material provided either the surface is free of an oxide film or the oxide film thickness and optical constants of this oxide film are known. The majority of ellipsometric measurements performed on materials known to grow natural oxides is done by removing the natural oxide (either by cleaving or etching) and performing the measurements at one angle of incidence in vacuo. These processes perturb the surface and the reported values of optical constants may be questionable. </p> <p> The technique to be presented here assumes the material to be studied has a naturally-occurring oxide. Measurements are performed at several angles of incidence and the optical equations are solved for a self-consistent oxide film thickness until the best fit substrate optical constants have been found. The optical constants of the oxide film are then determined. </p>