I have obtained psi and del values for different wavelengths for 3 different angles (VASE data).
How do I calculate refractive index using this data.
Ellipsometry is an indirect technic. As consequence, a physical model is necessary to reproduce the sample composition. In addition, a fitting for thickness, volume fraction and dispersion law parameters, corresponding to each composition, to reproduce the experimental measurment (psi and delta or Is and Ic).
I noticed you to read this two references :
1. R.M.A. Azzam, N.M. Bashara, Ellipsometry and Polarized Light, North-Holland,
Amsterdam, 1977.
2.M.-B. Bouzourâa, A. En Naciri and All., Materials Chemistry and Physics 175 (2016) 233-240.
Ellipsometry is an indirect technic. As consequence, a physical model is necessary to reproduce the sample composition. In addition, a fitting for thickness, volume fraction and dispersion law parameters, corresponding to each composition, to reproduce the experimental measurment (psi and delta or Is and Ic).
I noticed you to read this two references :
1. R.M.A. Azzam, N.M. Bashara, Ellipsometry and Polarized Light, North-Holland,
Amsterdam, 1977.
2.M.-B. Bouzourâa, A. En Naciri and All., Materials Chemistry and Physics 175 (2016) 233-240.
As already stated it all depends on the optical model of your sample. Things become in particular easy if you can consider your sample as semiinfinite with negligible surface roughness and characterized by a scalar dielectric function, since then you can simply invert the corresponding equations to obtain the complex index of refraction. So what kind of sample do you have?
Assuming that your sample is randomly oriented (with domains small compared to the wavelength), thick and smooth enough, it means that you can directly invert the formulas...
I expect that you are using some commercial package like Complete ease (JAW). In that case just use a blank model, select the Cauchy model and fit for coefficients A, B & C. Else, follow what Bouzourâa suggested.
However, from my experience, ellipsometry is not good for (optically) thick samples, in your case not more than 5 microns of PDMS. Else you will get too many reflections close together(will look like oscillations). If that's how your data is, you should look for some alternative method, may be spectroscopic reflectometry.
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