Ellipsometry

Abstract Ellipsometry, also known as reflection polarimetry or polarimetric spectroscopy, is a classical and precise method for determining the optical constants, thickness, and nature of reflecting surfaces or films formed on them. Ellipsometry derives its name from the measurement and tracking of elliptically polarized light that results from optical reflection. Typical experiments undertaken with this technique consist of measuring the changes in the state of polarization of light on reflection from the investigated surfaces. Hence, ellipsometry finds applicability in a wide variety of fields such as physical and chemical adsorption, corrosion, electrochemical and chemical formation of passive layers on metals, oxides, polymer films, semiconductor growth and microelectronics, biology, medicine, and immunological reactions. The main strength of this technique lies in its capability not only to allow in situ measurements and provide information about the growth kinetics of thin films but also simultaneously to allow the determination of many or all of the optical parameters necessary to quantify the system. Spectroscopic ellipsometry allows the accurate and swift characterization of optical constants and reflectivity for single and multilayer coatings with film thicknesses of from 0.1 nm to 30 μm. Phase‐modulated ellipsometry is more sophisticated and was developed in recent years thanks to the advent of computer control and multichannel detectors. Other configurations of ellipsometers for special purposes are tailored for qualification and online production control, photovoltaic applications and testing of solar cells, single or multiwavelength monitoring, and in situ film growth allowing the precise control of film deposition processes.