I've deposited TiO2 thin films on silicon substrates (not transparent), and have done reflectance measurements, so how can I extract thicknesses from reflectance measurements ?
I wonder which kind of reflectance data should I use to extract the thickness : the one of total reflectance or specular or diffuse ?
Assuming you're talking about visible light reflectometry, you can use ellipsometry concepts to fit your reflectance data to a model for TiO2 and extract thickness and refractive index. Did you do normal incidence/reflection measurements using a spectrum analyzer?
Here are a couple of resources to help you with basics:
1. https://www.jawoollam.com/resources/ellipsometry-tutorial
2. http://homes.nano.aau.dk/kp/Ellipsometry/main.pdf
You can also just google and get the model for fitting TiO2 reflectance data.
Assuming you're talking about visible light reflectometry, you can use ellipsometry concepts to fit your reflectance data to a model for TiO2 and extract thickness and refractive index. Did you do normal incidence/reflection measurements using a spectrum analyzer?
Here are a couple of resources to help you with basics:
1. https://www.jawoollam.com/resources/ellipsometry-tutorial
2. http://homes.nano.aau.dk/kp/Ellipsometry/main.pdf
You can also just google and get the model for fitting TiO2 reflectance data.
XRR method can be used to do the thin films thickness & internal stress analysis. We are using BRUKER D8 Discover XRD machine for this purpose & a software named as LEPTOS. In Leptos you can easily find out the thickness of each film (single as well as multilayered sample).
From the extremums of the reflectance spectra, you should be able to extract the thickness and the optical constant of the film, assuming that you know the optical constant of the substrate quite well.
There are a few papers that use an 'envelope' technique similar to that of Manifacier or Swanepoel for transmittance spectra to extract the dispersion of n and k, as well as to get a good estimation of the thickness. I give here the link to one of these papers.
http://dx.doi.org/10.1016/j.optlastec.2008.05.022
The given link might be of some help.
http://www.helmholtz-berlin.de/forschung/oe/ee/nanooptix/refdex/index_en.html
thanks for your quick responses, I'll work each method and see the reult.
1- Trivedi : thank you but our ellipsometry technique is inoperative but Yes used spectrophotometry normal incidence/reflectance measurements,
2- Mukim :thank you too,unfortunately we don't have XRR method;
3- Poitras: I thought envelop method is only valid for transparent substartes like glass (transmittance) but not for Si substrates for example (reflectance)?!
4- Gorji: I'll try to do the same thing, thank you;
5- Bhatnagar : thank you too for your help;
I will try out every proposition and see the one fits me.
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