ABSTRACT
One of the most important applications of polarized light is the measurement of the complex refractive index and thickness of thin films. A field of optics has been developed to do this and has come to be known as ellipsometry. In its broadest sense, ellipsometry is the art of measuring and analyzing the elliptical polarization of light. The name appears to have been given in 1945 by Alexandre Rothen [1], one of the pioneers in the field. However, the field of ellipsometry has become much more restrictive, so that now it almost always applies to the measurement of the complex refractive index and thickness of thin films. In its most fundamental form, it is an optical method for measuring the optical parameters of a thin film by analyzing the reflected polarized light. The optical parameters are the refractive index n, the extinction coefficient κ, and the thickness d of a thin film deposited on a substrate. The optical procedure for determining these parameters is done in a very particular manner, and it is this manner that has come to be known as ellipsometry. The fundamental concepts of ellipsometry are quite simple and straightforward; however, we shall see that this seeming simplicity is deceptive. Nevertheless, the method is very elegant.
