Ellipsometric data analysis used in on-line metal passivation monitoring
Gdańsk University of Technology, Department of Optoelectronics, Narutowicza 11/12 Street, 80-952 Gdańsk, Poland
2 Gdańsk University of Technology, Department of Electrochemistry, Corrosion and Materials Engineering Narutowicza 11/12 Street, 80-952 Gdańsk, Poland
Metal oxide thin films, suitable for use on solar energy converters and photocatalitic applications, have been characterized on-line by ellipsometric monitoring system. Ellipsometry is a powerful and non-invasive technique of film analysis but it is indirect tool. The most interesting parameters such as film thickness and complex refractive indices can be determined only by computer sample modelling. The complex reflection coefficients obtained from model calculation were compared with ellipsometric measurements. We discuss composition of multilayer film structure using various models and fittings method. The implementation of effective medium approximation procedure enables to interpret multilayer oxides structure formation during passivation process. It is shown that an accurate model fitting was obtained using Levenberg-Marquardt optimization algorithm and multidimensional mean square error.
© EDP Sciences, Springer-Verlag, 2007