We have prepared a film using spin coating. Can anyone help to find the thickness and refractive index of the film? In uv-vis we have not got interference fringes, other than SEM or ellipsometry. Is there any other method to find thickness and ref. index.
The film thickness can be measured by x-ray reflectometry with high accuracy for thicknesses of below 200nm.
Could use surface plasmon resonance measurements or use AFM after carefully scratching the sample with soft materials.
Focused ion beam could be an option, you can cut the sample and observe the cross section in vacuum, from cross section you can estimate or find your thickness if you have smooth layer.
As Hans-Ulrich Krebs suggested X-ray reflectivity is very powerful technique to determine the film thickness below 1-2 micron. XRR will also tell you roughness of the film and substrate and you may have idea about the density of your film.
For thickness, optical and/or mechanical profilometer would help and ellipsometry for refractive index of the spin coated films.
It depends on the thickness but you can estimate it by the interference pattern through optical absorption spectrum
If your samples are transparent then methods based on Inteferometer could be used..
A standard benchtop method of characterising thin films where the refractive index is relevant is called ellipsometry. Google it, or see how it was used in one of these papers:
http://iopscience.iop.org/0295-5075/27/1/011/pdf/0295-5075_27_1_011.pdf
http://pre.aps.org/pdf/PRE/v56/i5/p5705_1
I agree, as long as the films are not to rough, standard ellipsometry is the easiest method giving you all data you want at once. If it is rough, imaging ellipsometry can be tried.
PS: ellips. should be done at least either in the spectroscopic mode or angle resolved, better both.
For simultaneous determination of refractive index (n), absorption coefficient (k) and thickness (d) we used the so called triple method (T, Rf, Rm). We deposited films on two types of substrates-optical glass (BK7) and Si-substrate and measured transmittance (T) and reflectance (Rf) of the film deposited on BK7 and reflectance (Rm) of the film deposited on Si-substrate. Further at each wavelength we determined n, k and d by solving three equations in the form (Fmeas-Fcalc=0), where "meas" and "calc" are measured and calculated spectra (T, Rf and Rm).
Another possibility is to use dispersion models for description of n and k and using non-linear curve fitting for determination of n, k and d from measuring reflectance of the film (or T, or T and R)
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